spectroscopic-atlas-5_0-english_Neat

Spectroscopic Atlas for Amateur Astronomers 151

By pushing off the envelope and the progressive “exposing” of increasingly hotter, inner
stellar layers, central stars of PN may generate spectra, simulating substantially more mas-
sive and luminous stars. This applies, for example, for all O-, early B- and WR-
classifications! However the progenitor stars of planetary nebulae are limited to maximum
8 solar masses, corresponding to the middle B class.

Table 80 Orion Nebula M42, NGC1976 Object type: HII region Excitation class: E1

T80 shows the emission spectrum of M42 (approx. 1400 ly) taken in the immediate vicinity
of the trapezium θ1 Orionis. Main radiation source is the C- component, a blue giant of the
rare, early spectral type O6 (see Table 3) with a temperature of approx. 40,000K [207]. To-
gether with the other stars of the early B-Class, it is capable to excite the surrounding neb-
ula with the criterion value ‫ܫ‬ேଵାேଶ /‫ܫ‬ுఉ ≈ 5 up to the border area between the classes E1
and E2. The Hβ line is here just slightly surpassed by the [O III] (λ 4959) emission. Due to
the enormous apparent brightness the object is spectrographically easy accessible and re-
quires only modest exposure times. (10x30 seconds).

Table 80A Orion Nebula M42 Intensity profiles within the central part of the nebula

T80A shows for the [O III] (λ5007) and Hβ emission lines the intensity profiles along the
entire length of the slit array (some 2.5 ly), within the central region of the nebula (Photo
M42: HST). The ratio of these intensities demonstrates indirectly the course of the excita-
tion class. Thanks to the linear arrangement of the three slits, DADOS allows for 2-
dimensional appearing objects an improvised "Long-slit" spectroscopy, which enables to
gain spectral information, combined with the spatial dimension. These profiles have been
generated with Vspec and 1D-spectral stripes, rotated by 90° with the IRIS software. On
the narrow bridges between the individual slits the intensity curve is supplemented with
dashed lines. After recording of the spectra in each case a screenshot of the slit camera
was taken to document the exact location of the slit array within the nebula.

The different width of the three slits (50/25/30 μm) plays a little role for this purpose,
since just the intensity course is recorded and IRIS averages anyway the gray values within
the whole slit width. The slit array was positioned on two places within the central part of
M42 and approximately aligned in the North-South direction. The western section runs
through the C- component of the brightest Trapezium star Θ1 Orionis C (Table 3) and ends
at the so called Orion Bar. The eastern section runs along the Schröter-Bridge, through the
Sinus Magnus and finally also the impressive Orion Bar, southeast of the Trapezium. The
intensity scales of the profiles are normalised on the spectral peak value of [O III] = 1 within
the Orion Bar and the peak of Hβ on the local ratio there of [O III]/Hβ ≈ 2.5.

Striking is the dramatic increase of intensity within the area of the Trapezium and in the
huge ionisation front of the Orion Bar. The latter marks the end of the ionised H II region or
the so called Strömgren Radius. At the end of this transition zone the nebula is heated up to
just several 100 K, by the remaining UV photons with energies <13.6 eV which, below this
Lyman limit, could not be absorbed by the ionisation processes within the H II area. Outside
this transition zone follow chemically increasingly complex molecular clouds [404].

Also remarkable is the sharp drop of the intensity within the dark cloud in the Sinus Magnus
and the slight increase in the range of the Schröter Bridge. The C- component of θ1 Orionis
produces here about 80% of all photons [223]! Without it, only a much smaller part of the
nebula would be ionised, i.e. the corresponding Strömgren Radius Rs would be significantly
shorter. Calculated for a relatively "dense" gas (relative to H II regions) of 103 cm-3 and an
O6 star with 43,600K yields Rs ≈ 3 ly (0.9pc). For B0 stars this value drops to Rs ≈ 1.2ly
(0.36pc) [404]. The lower the density of the nebula the greater will be the Strömgren Ra-
dius, because comparatively lesser photons will be absorbed within the same route.

Spectroscopic Atlas for Amateur Astronomers 152

Table 81 Spirograph Nebula IC 418 Object type: PN Excitation class: E1

Spectrum of IC 418 (approx. 2500 ly). The central star has here a
temperature of only 35,000K [207]. It is still unstable, highly vari-
able within short periods of time and therefore just able to excite
this nebula with the criterion value ‫ܫ‬ேଵାேଶ /‫ܫ‬ுఉ ≈ 2.8 to the lowest
class E1 (Gurzadyan: E1 [206]). This is still lower than in the H II
region M42. Further Hβ here even outperforms the intensity of
[O III] (λ 4959). Accordingly, the PN stage must be still very young
and also the diameter of the ionized shell is estimated to just 0.2
ly [207]. The complex spirograph pattern in the nebula is still not
understood. Exposure time with the C8 is 3x170 seconds. Photo: HST.

Table 82 Turtle Nebula NGC 6210 Object type: PN Excitation class: E4

Spectrum of NGC 6210 (approx. 6500 ly). The central star has
here a temperature of approx. 58,000K [207] and is classified as
O7f. It excites this nebula with the criterion value ‫ܫ‬ேଵାேଶ /‫ܫ‬ுఉ ≈ 14
slightly below the threshold of class E4 (~consistent to Gurzad-
yan: E4 [206]). In the spectrum appears here, only very weak, the
He II line (λ 4686). In some cases, this line can also be emitted
directly from the central star [206]. Exposure time with the C8 is
4x45 seconds. Photo: HST.

Table 83 Saturn Nebula NGC 7009 Object type: PN Excitation class: E8

Spectrum of NGC 7009 (approx. 2000 ly). The central White
Dwarf has a temperature of approx. 90,000K [207]. It excites this
nebula with the criterion value log(‫ܫ‬ேଵାேଶ /‫ܫ‬ு௘ ூூ (ସ଺଼଺)) ≈ 1.9
up to the class E8. (Gurzadyan: slightly different: E7 [206]). The
blue profile is strongly zoomed in the intensity to make the weaker
lines visible. Striking are here, despite the high excitation class,
still intense H emissions and a too low Balmer decrement of D
<2.8, (possible influences sect. 28.7). This PN is the first whose
expansion could be detected photographically. [202]. Exposure
time with the C8 is 7x240 seconds. Photo: HST.

Table 84 Ring Nebula M57, NGC 6720 Object type: PN Excitation class: E10

T84 shows the emission spectrum of M57 (approx. 2300 ly) approximately in the center of
the Ring Nebula. The central White Dwarf has a temperature of approx. 150,000K [207]. It
excites this nebula with the criterion value log(‫ܫ‬ேଵାேଶ /‫ܫ‬ு௘ ூூ (ସ଺଼଺)) ≈ 1.4 up to the class
E10 (consistent to Gurzadyan: E10 [206]).

Accordingly weak are here the hydrogen lines relative to [O III]. The Hα line here just
reaches parity with the weaker [N II] (λ 6548) emission. The much stronger [N II] (λ 6584)
line however is the second-most intense emission behind [O III] (λ 5007). Therefore the
reddish colour within the ring of M57 predominantly originates from [N II] instead of the by
far weaker Hα line.

The broadband spectrum (left) was taken with the 90cm CEDES Cassegrain Telescope in
Falera, slit width: 25μm, exposure time 5x340 seconds. This was obviously too short to
show the weak classification line He II (λ 4686). However, this was later achieved with the
C8, the low-resolution 50μm slit and an exposure time of 3x1270 seconds (excerpt of the

Spectroscopic Atlas for Amateur Astronomers 153

spectrum to the right). This reflects the high effort, required for these large appearing PN
(in this case 86"x72"). Typical for this high excitation class are the old age of about 20,000
years, and the large extent of the nebula of about 1.4 ly.

Table 84A M57, Intensity profile along the longitudinal axis of the Ring Nebula

T84A shows for the strongest emission lines [O III] and [N II], the intensity profile along the
entire 50μm slit, positioned on the longitudinal axis of the Ring Nebula. This profile has
been generated with Vspec and a 1D-spectral stripe, rotated by 90° with the IRIS software.

Table 85 Red Rectangle Object type: Post AGB Star/ Excitation class: very low,
Nebula HD44179 Protoplanetary Nebula can't be determined quan-
titatively with sect. 28

This highly interesting object, discovered not until 1974, is a
protoplanetary nebula which is located at a distance of about
2'300ly in the constellation Monoceros. With an apparent mag-
nitude of Vvar= ~+9.02m the so called Post-AGB-Star has just left
the last carbon-star-stage on the AGB and begins now to repel
its envelope as a planetary nebula. In amateur telescopes the ob-
ject is visible just as a star. Only large professional telescopes
show the small bi-cone-shaped nebula. Image HD44179: by
HST. The object is a spectroscopic binary. By repelling its envelope, the ex-carbon star has
changed its spectrum radically and presents itself now as spectral type, depending on the
source, in the range of a B8 to A0 giant. This would correspond to an effective temperature
of about 10'000K. However, for the Post AGB component just 7500 – 8000K are assumed
[eg 208]. The corresponding ionisation energy is still by far too low for an ionisation of the
nebula, so here just the hydrogen Hα-and the sodium D1/D2 lines appear in emission.
Highly-resolved spectra show here the Na I emissions with double peaks, what is inter-
preted as a combination of perspective- and Doppler effects, caused by the bipolarly occur-
ring mass loss [208]. In such spectra C2 Swan emissions testify from the former stage as a
carbon star [209]. The slim hydrogen absorptions indicate a photosphere or rather a
pseudo-photosphere of low density.

Table 86 M1, NGC 1952 Object type: SNR Excitation class: E >5

T86 shows the emission spectrum of the Supernova Remnant (SNR) M1 (approx. 6300 ly).
The 50μm slit runs in ~N–S direction through the central part of this young SNR. The causal
SN type II was observed and documented in 1054 by the Chinese. Today, the diameter of
the expanding nebula reaches approximately 11 ly.

Vesto Slipher in 1913 recorded the first spectrum of M1. At that time he already noticed a
massive split up of the most intense emission lines. Unaware of the nebula expansion, he
interpreted this spectral symptom incorrectly as the newly discovered Stark effect caused
by the interaction with electric fields. 1919 exposed R.F. Sanford, the M1 spectrum with
the 2.5m Hooker Telescope, and at that time the "fastest" film emulsions, while no fewer
than 48 hours! The result he describes sobering as "disappointingly weak", a well clear in-
dication that even today this can’t be really a beginner object. The expansion of the nebula
was found not until 1921 by C.O. Lampland, by comparing different photographic plates!

With the C8, a 200L grating and an Atik 314L+ camera, cooled to –20°C with 2x2 binning
mode, after all still 2x30 minutes were needed to record a spectrum of passably acceptable
quality. As an annoying side effect of the long exposure time, light pollution and airglow
(Table 96) was recorded in a comparable intensity to the signal of M1, despite a quite

Spectroscopic Atlas for Amateur Astronomers 154

passable rural sky with a visible magnitude of maximum about 4–5m. This disturbing spec-
trum was therefore recorded separately, just outside the nebula, and afterwards subtracted
with Fitswork from the M1 signal.

This apparently almost 1,000 years old expanding shell is meanwhile diluted to such an ex-
tent, that it has become optically transparent. This show also the redshifted peaks of the
split, well shaped emission lines, often appearing of similar intensity like the blue-shifted,
but in some cases however significantly weaker.

The chart at right explains the split up of the O III
emission lines due to the Doppler Effect. The
parts of the shell which move towards earth Direction
cause a blue shift of the lines and the re- earth
treating ones are red shifted. Thereby, they
are deformed to a so-called velocity ellipse.
This effect is seen here at the noisy [O III]
lines of the M1 spectrum – below the 50μm
slit, on the top the 25μm slit.

At this low resolution the red-shifted peak of the [O III] (λ 4959) emission forms a blend
with the blue-shifted peak of the [O III] (λ 5007) line. Due to the transparency of the SNR,
with the split up of Δλ, as already shown in Table 2 and in [30], the total expansion velocity
of the matter can be determined, related on the diameter of the shell (here, about
1800km/s). The radial velocity is obtained finally by halving this value. The radial velocity of
this young SNR yields just below 1000 km/s – about 50 times higher than in PN.

By contrast, the envelopes of Wolf Rayet stars (Table 5), P Cygni (Table 13/13A) and to an
extreme extent also of Novae and Supernovae are so dense that we see only the hemi-
sphere of the expanding shell, heading towards the earth. In these cases we measure di-
rectly the radial velocity, applying the Doppler formula.

Even more spectral symptoms show that SNR are a special case within the family of the
emission nebula. In the center of the nebula (Profile B), due to synchrotron and
Bremsstrahlung processes (see [30]) a clear continuum is visible, which is very weak in the
peripheral regions of the SNR (A). The latter profile was even slightly raised to make here
readable the labelling of the wavelength axis. In contrast to the SNR it is difficult to detect a
continuum in the spectra of PN and H II regions.

The line intensities ‫ ܫ‬of the profiles B1, 2 were adapted relative to the continuum heights
(‫ܫ‬/‫ܫ‬௖), to become roughly comparable with those of profile A. Apparently in profile A and B
the emissions in the range around λ 6500 are of similar intensity. However, in the periph-
eral area of the nebula (profile A), the [O III] lines around λ 5000 are several times stronger.
Obviously the conditions for forbidden transitions are here much more favourable than in
the vicinity of the high-energy pulsar, the stellar remnant of the SN explosion. This state-

ment is relativised by the uncertainty, whether and to what extent the rudimentary subtrac-
tion of light pollution has affected the course of the continuum.

Due to shock wave induced collisional-excitation the strikingly intense sulphur doublet (λλ
6718/33) becomes clearly visible. This feature is only weak in PN and almost completely
absent in H II spectra. This also applies to the [O I] line at λ 6300. Anyway at this resolution
it can hardly be separated from the [O I] airglow line at the same wavelength (see sect. 31).

Spectroscopic Atlas for Amateur Astronomers 155

Table 87 NGC 6888 Crescent Nebula Object type: WR-Nebula Excitation class: E1

T87 shows the emission spectrum of the Crescent Neb- N
ula NGC 6888, located in the constellation swan (some W
4700 ly). The picture (Wikipedia/Hewholooks) shows
the nebula WR 136, the location of the recorded spec- WR136
trum within the shock front, and the position of the im-
age detail on Table 87.

Origin and ionising source of NGC 6888 is the Wolf
Rayet star WR 136, which is described in sect. 9, Table
6. In the previous giant stage, the star has already re-
pelled a part of its gas shell. After the transition to the
WR stage, about 30,000 years ago [240], the mass loss
intensified dramatically to about 10−5 to 10−4 M per year [236] and the stellar wind accel-
erated to more than 1000 km/s. This violent stellar wind collides with interstellar matter
and the gas layer, which was repelled earlier during the former giant stage of the star. This
process generates an elliptically shaped shock front, expanding with some 75 km/s [240]
to currently ~16 x 25 ly [237]. Similar to the SNR, this shock front is chiefly responsible for

the ionisation and also for the fluffy pattern of the Crescent nebula. Within WR Nebulae,
these processes apparently run much less violently as within SNR. For comparison; the

shock wave of M1 expands with ~1000 km/s. Anyway, this object is still some 30 times
younger than NGC 6888. In WR nebulae also a central pulsar or neutron star is missing,
which in SNR generates a permanent, relativistic electron wind, combined with the effects,
described in Table 86.

The repelling of the hydrogen shell happens at the very beginning of the Wolf Rayet stage.
Accordingly, later on, hydrogen can hardly be detected anymore in the spectra of WR stars
(sect. 9). With a dynamic age of about 30,000 years [240], WR 136 just passed some 10%
of the entire, estimated WR sequence of ~200,000 years [237].

The spectrum was recorded with the 25μm slit and the 200L grating, just west of the star
HD 192182 and within the outer shock front of the nebula. A continuum cannot be found
here. The profile in Table 87 was shifted just slightly upwards, to make visible the labelling
of the wavelength axis. In contrast to M1 the degree of excitation of the plasma is E1 and

therefore very low. The Hβ emission is even more intense than the [O III] line at λ 4959.
Certainly, this can also be attributed to the advanced age of the nebula. In addition to the
typical hydrogen- and O III emissions, only neutral helium He I, as well as forbidden lines of
ionised nitrogen [N II] can be observed. The forbidden sulphur doublet [S II] at λλ 6718/33,
a characteristic feature for shock waves, barely rises here above the continuum noise level.

With the C8 and the camera Atik 314L+, cooled to -20° C, after an exposure time of 2x30
minutes in the 2x2-binning mode, a slightly noisy, but for this purpose anyway useful profile
resulted. On all shots, the separately recorded light pollution and the airglow (Table 96) had
to be subtracted (Fitswork). Under the prevailing conditions, the nebula remained invisible
in the flip mirror, even with help of the O III filter. The slit of the spectrograph was posi-
tioned on the selected nebula-filament with help of the field stars pattern.

Spectroscopic Atlas for Amateur Astronomers 156

Table 88 NGC 2359 and WR 7 Object type: WR-Nebula Excitation class: E3

The Wolf Rayet star WR 7 in the constellation Great Dog is
the ionising source for the well known emission nebula
NGC 2359 Thor's Helmet. Picture on the right: NGC 2359

(ESO B. Bailleul). Table 88 shows both, the spectrum of
the nebula as well as the ionising WR star with spectral
type WN4. It is equally classified as WR 133 on Table 5. In
contrast to the latter, however, the profile of WR 7 is not

imprinted by the absorption of a close companion star. It
shows therefore the uncontaminated He II Pickering se-
ries, similar to WR 136 (type WN6) on Table 6 (see. sect.
9.6). However, WR 7 is classified earlier (type WN4) and
thus somewhat older and already hotter than WR 136.
Whether this is the cause for the significantly higher exci-
tation class of E3, measured at a comparable location within the outer shock front, cannot
be clarified here. The somewhat older NGC 2359 with an extension of about 30 light years

is slightly larger than NGC 6888 with about16 x 25 ly. The distance to NGC 2359 is about
15,000 ly and thus about 3 times as large as to NGC 6888 (see sect. 9.6). This nebula is
therefore somewhat fainter. Recording data and corresponding details see Table 87.

28.13 Distinguishing Characteristics in the Spectra of Emission Nebulae

Here, the main distinguishing features are summarised again. Due to the synchrotron and
Bremsstrahlung SNR show, especially in the X-ray part of the spectrum, a clear continuum.
X-ray telescopes are therefore highly valuable to distinguish SNR from the other nebula
species, particularly by very faint extragalactic objects. For all other types of emission nebu-
lae the detection of a continuum radiation is difficult.

In the optical part of SNR and to some extent also in WR spectra, the [S II] and [O I] lines
are, relative to Hα, more intense than at PN and H II regions, due to additionally shock wave
induced collision ionisation. The [S II] and [O I] emissions are very weak at PN and almost
totally absent in H II regions [204].

In SNR the electron density ܰ௘ is very low, ie somewhat lower than in H II regions. It
amounts in the highly expanded, old Cirrus Nebula to about 300 cm-3. By the still young and
compact Crab Nebula it is about 1000 cm-3 [204]. By PN, ܰ௘ gets highest and is usually in
the order of 104 cm-3 [204]. In the H II region of M42, ܰ௘ is within the range of 1000–
2000 cm-3 [224]. The determination of ܰ௘ and ܶ௘ from the line intensities is presented in
[30].

In H II regions, the excitation by the O- and early B-class stars is relatively low and therefore
the excitation class remains in the order of just approx. E = 1-2. Planetary nebulae usually
pass through all 12 excitation classes, following the evolution of the central star.

In this regard the SNR are also a highly complex special case. By very young SNR, eg the
Crab Nebula (M1), dominate higher excitation classes whose levels are not homogeneously
distributed within the nebula, according to the complex filament structure [222]. The diag-
nostic line He II at λ 4686 is therefore a striking feature in some spectra of M1, ([222] and
Table 86).

Spectroscopic Atlas for Amateur Astronomers 157

TABLE 80 Richard Walker 2010/09©

Excitation class E1 [N ll] 6583.6

Hα 6562.82

Criterion IN1+N2 /Hβ ≈ 5 He I 5876

[O lll] 5006.84

[O lll] 4958.91
Hβ 4861.33

Orion Nebula M42 Hγ 4340.47

Classification lines

Spectroscopic Atlas for Amateur Astronomers 158

TABLE 80A

Trapezium W
N
Θ1 Ori C
Θ2 Ori A
Pons
Schröteri

~ 1.6‘ Sinus
Magnus

Intensity Profiles [O III], Hβ Θ1 Ori C
Trapezium Area

Intensity [O III]
Hβ

Trapezium Orion Bar

Intensity Profiles [O III], Hβ
Sinus Magnus

Intensity [O III]

Pons Schröteri Sinus Magnus Hβ
Nebula Sectors
Orion Bar

Spectroscopic Atlas for Amateur Astronomers 159

TABLE 81 [Ar III] 7135.8
He I 7065.2

[N ll] 6583.6 [S II] 6717 / 31
Hα 6562.82 He I 6678.1

[N ll] 6548.1

[O I] 6300.2

Excitation Class E1 He I 5876
[N ll] 5754.8

Spirograph Nebula IC 418 [O lll] 5006.84

Criterion IN1+N2 /Hβ ≈ 2.8 Classification lines [O lll] 4958.91
Hβ 4861.33

He I 4471.5
Hγ 4340.47

Hδ 4101.74

Spectroscopic Atlas for Amateur Astronomers 160

TABLE 82

[O lll] 5006.84

[O lll] 4958.91

Classification lines Hβ 4861.33

He II 4685.7

[N ll] 6583.6
Hα 6562.82

Excitation Class E3 He I 5875.6

Turtle Nebula NGC 6210 Criterion IN1+N2 /Hβ ≈ 14 [CI III] 5517.3

[O lll] 5006.84
[O lll]4958.91
Hβ 4861.33
He II 4685.7

Hγ 4340.5

[Ne III] 3869

Spectroscopic Atlas for Amateur Astronomers 161

TABLE 83 [N ll] 6583.6 Richard Walker 2011/12©

Hα 6562.82

Classification lines He I 5875.6

Excitation class E8

Saturn Nebula NGC 7009 [O lll] 5006.84
[O lll] 4958.91
Criterion log (IN1+N2 /IHe II (4686))≈ 1.9
Hβ 4861.33 [Ar IV] 4740.3
[Ar IV] 4711.34

He II 4685.7

[N III] 4641

He I 4471.5
[O lll] 4363.2

Hγ 4340.5

Hδ 4101.74

[Ne III] 3967.47
[Ne III] 3868.76

Spectroscopic Atlas for Amateur Astronomers 162

TABLE 84 Richard Walker 2010/05©

[O lll] 5006.84

Classification lines [O lll] 4958.91
Hβ 4861.33

He II 4685.7

Excitation Class E10 [S ll] 6732.7
[S ll] 6718.3

[N ll] 6583.6

Hα 6562.82
[N ll] 6548.1

[O l] 6363.88
[O l] 6300.23

Ring Nebula M57 [O l] 5577.4

Criterion log (IN1+N2 /IHe II (4686))≈ 1.4 [O lll] 5006.84

[O lll] 4958.91
Hβ 4861.33

Spectroscopic Atlas for Amateur Astronomers 163

TABLE 84A

Ring Nebula M57 Intensity Profile [O III] λ 5007

Longitudinal section through
M57. The 50μm slit of DADOS is
approximately aligned with the
longitudinal axis of the nebula.
With Vspec the Intensity profiles
of the strongest emissions [O III]
and [N II] are generated along
the entire length of the slit. The
scales of the two profiles are
normalized on the peak value of
[O III] =1, proportional to their
line intensity in the spectrum.
[N II] chiefly generates the
reddish yellow edge part of the
nebula, [O III] mainly produces
the turquoise-blue color in the
center of the Nebula (Photo:
HST).

Intensity Profile [N II] λ 6584

Spectroscopic Atlas for Amateur Astronomers 164

TABLE 85Red Rectangle Nebula HD44179Telluric O2 6870
??
Hα 6562.82
Richard Walker 2014/02©
Telluric O2

Na l 5889/96

Hβ 4861.33

Hγ 4340.47

Hδ 4101.74
Hε 3970.07
H8 3889.05
H9 3835.38

Spectroscopic Atlas for Amateur Astronomers 165

TABLE 86 Δλ ≈ 30Å

B2 [S ll] 6732.7 Richard Walker 2012/02©
[S ll] 6718.3
Δλ ≈ 41Å

[N ll] 6583.6
Hα 6562.82

[O I] 6300.23

SNR M1 / NGC 1952 B Excitation class E > 5 He I 5875.6
N
50μ Spalt

A

W

Δλ ≈ 31Å Δλ ≈ 28Å

A

B1 [O lll] 5006.84

[O lll] 4958.91
Hβ 4861.33
He II 4685.7

Spectroscopic Atlas for Amateur Astronomers 166

TABLE 87 [S ll] 6718/33 ©Richard Walker 2013/01

Hα 6562.82 [N ll] 6583.6

[N ll] 6548.1

Crescscent Nebula NGC 6888, Type Wolf Rayet (WR136) [O I] 6300.2

WR136

Excitation class E1 HD192182 He I 5876

N
W

Criterion IN1+N2 /Hβ ≈ 3.3 Classification lines

[O lll] 5006.84

[O lll] 4958.91
Hβ 4861.33

Spectroscopic Atlas for Amateur Astronomers 167

TABLE 88 [S ll] 6718/33 ©Richard Walker 2014/04
[N ll] 6583.6
N N IV 7102- 29 Hα 6562.82

WR 7 He ll 6890.9 [N ll] 6548.1
Telluric O2
W He ll 6683.2 [O I] 6300.2

He ll 6560.1

NGC 2359 „Thor‘s Helmet“ with WR 7, HD 56925 NGC 2359

WR 7 HD 56925 WN 4 C lV 5801-12

He ll 5411.52 Criterion IN1+N2 /Hβ ≈ 12
Excitation class E3
He l 5015.68
N V 4933/44 Classification lines
He ll 4859.32
He ll 4685.7 [O lll] 5006.84
N V 4603/19
He ll 4541.59 [O lll] 4958.91
Hβ 4861.33

He ll 4338.67
He ll 4199.83
He ll 4100.04

Spectroscopic Atlas for Amateur Astronomers 168

29 Reflectance Spectra of Solar System Bodies

29.1 Overview

The objects in our solar system are not self-luminous, and visible only by reflected sunlight.
Therefore, with exception of comets, these spectra always show, not surprisingly, the ab-
sorption lines of the Sun. On the other hand the spectral continua of the reflected profiles
are overprinted, because certain molecules, e.g. CH4 (methane), in the atmospheres of the
large gas planets, are reflecting or absorbing the light differently strong within specific
wavelength ranges (wavelength-dependent albedo). Already 1871, Angelo Secchi had dis-
covered these dark, at that time not identifiable bands. This was achieved not until 1930 by
Rupert Wild and Vesto Slipher.

29.2 Commented Spectra

According to their characteristics the planetary reflectance spectra are distributed here to
three tables, and compared with the continuum of the sunlight. All profiles (200L grating)
have been recorded at an elevation of some 30 – 40° above the horizon and are equally
normalised to unity.

29.3 Reflectance Spectra of Mars and Venus

Table 90:

The extremely dense atmosphere of Venus generates on the surface a pressure of about 90
bar, ie approximately 90 times as high as on Earth. It consists of about 96% carbon dioxide
(CO2). The remaining shares are mainly nitrogen (N2), water vapour (H2O), and sulphur
compounds in the form of sulphur dioxide (SO2) and sulphuric acid (H2SO4). The extremely
thin atmosphere of Mars consists similar to Venus, to about 96% of CO2, but here under a
surface pressure of only 0.006 bar, i.e. <1% of the value on the surface of the Earth. Here
particularly the rocky surface of the planet might determine the reflectance properties. In
the displayed range the spectra neither of Venus nor Mars show significant deviations from
the shape of the Sun’s spectral continuum. In higher resolved spectra, of course experts
can recognise and analyse differences.

29.4 Reflectance spectra of Jupiter and Saturn

Table 91:

The outer atmosphere of Jupiter consists of about 89% hydrogen and10% helium, the rest
mainly of methane and ammonia. These gases have hardly any influence on the reflectance
characteristics (continuum course), in contrast to the small rest which mainly consists of
methane (CH4) and ammonia (NH3).

Saturn's outer atmosphere is composed slightly different. It consists of about 93% hydro-
gen and only close to7% of helium. Further some traces appear of methane, ammonia and
other gases. Impressive to see here are, concentrated in the near-infrared range, the very
broad methane (CH4) and ammonia (NH3) absorption gaps in the spectral continuum. In this
wavelength domain, these differences appear most pronounced in the areas of 6200 and λ
7300.

29.5 Reflectance spectra of Uranus, Neptune and Saturn-Moon Titan

Table 92:

The atmospheres of Uranus and Neptune show a similar composition like Jupiter and Sat-
urn. Due to the much greater distance from the Sun their temperatures are so low that a
majority of components, such as ammonia and methane, are below their specific freezing

Spectroscopic Atlas for Amateur Astronomers 169

point. Thus Uranus and Neptune are also called "ice planets". Their reflectance spectra are
strikingly similar. At Uranus however, the absorptions are much more intense.

Compared with the gas planets Jupiter and Saturn, these effects generate here different
reflectance spectra with much more intense absorptions, which additionally appear even in
the short-wave region [380]. These absorptions are generally responsible for the bluish
colour of the outer two ice planets.

Titan, with a diameter of 5,150 km, is after Ganymede the second largest planet in the so-
lar system, but the only one who has a dense atmosphere, chiefly consisting of nitrogen.
Anyway the surface and outer mantle of the moon consist of ice and methane hydrate.
Similar to the Earth, Titan has a liquid cycle, but working here with methane instead of wa-
ter. Similar to Jupiter and Saturn the corresponding absorptions are limited here on the
long-wavelength (red) section of the spectrum.

In the reflectance spectra of Table 92, the absorptions of the solar spectrum are hardly rec-
ognisable.

29.6 Comet C/2009 P1 Garradd

Table 94:

Comets, like all other objects in the solar system, reflect the sunlight. However on its
course into the inner solar system core material increasingly evaporates, flowing out into
the coma, and subsequently into the mostly separated plasma- and dust tails. The increas-
ing solar wind, containing highly ionised particles (mainly protons and helium cores), ex-
cites the molecules of the comet. Thus the reflected solar spectrum gets more or less
strongly overprinted with molecular emission bands, – chiefly due to vaporised carbon
compounds of the cometary material. The most striking features are the C2 Swan bands,
above all, the band heads at λλλ 5165, 5636 and 4737 (see also sect. 32.2 and the com-
ments on Table 110). Further frequently occurring emissions are CN (cyan) at λλ 4380 and
3880, NH2 (Amidogen Radicals), and C3 at λ 4056. In 1910 the discovery of cyan in the
spectrum of comet Halley caused a worldwide excitement, because by the traversing of the
comet-tail the formation of hydrocyanic acid in the Earth's atmosphere was feared.

Sometimes also Na I lines can be detected. Only slightly modified is the solar spectrum, re-
corded from sunlight, which has been exclusively reflected by the dust tail. A comprehen-
sive catalog of cometary emission line can be found in [210] and additional data also in
[110].

All these facts and the associated effects create complex composite spectra. The influence
of the possible components depends primarily on the current intensity of the core erup-
tions, as well as on our specific perspective, regarding the coma, as well as the plasma- and
dust tail.

In Table 94, the coma profile of C/2009 P1 Garradd is presented, taken on November 17
2011, 1730 GMT. Exposure time with the C8: 3x900s. Shown is a montage of the comet
profile together with the C2 Swan bands, generated with a butane gas burner. This com-
parison clearly shows that in this spectrum of comet Garradd only two of four C2-
bandheads at λλ 5165 and 4715th are visible. The missing two are overprinted by molecu-
lar CH, CN and NH2 emissions. Absorptions of the solar spectrum are hardly recognisable
here. This became clear by a test superposition of the comet profile and the solar spectrum.
At the bottom of Table 94 the influence ranges of different molecules on the emissions of
the spectrum are presented, according to the Tables of [210]. Those are based on spectral
profiles, which were obtained with a high-resolution Echelle spectrograph (R ~ 40,000). It
is noticeable that, apart from some isolated emissions, overlapping of the influence regions
can barely be found.

Spectroscopic Atlas for Amateur Astronomers 170

TABLE 90 Telluric O2
Telluric H2O
Reflection spectra of Mars and Venus compared to the daylight Telluric O2
Hα 6562.82
Sun (daylight)
Mars (CO2 ,Gestein)Na l 5980/96

Venus (CO2, N2)Magnesium
Richard Walker 2010/05©Triplet

Hβ 4861.33

Reflectance Spectra of Jupiter and Saturn compared to the Day Light Spectroscopic Atlas for Amateur Astronomers

Sun (Day Light) Telluric O2 Telluric H2O Telluric O2 TABLE 91

Jupiter (H2, He, CH4, NH3)

Saturn (H2, He, CH4, NH3)

CH4

NH3 CH4
CH4
Hα 6562.82

Na l 5890/96

Magnesium
Triplet
Hβ 4861.33

©Richard Walker 2010/05 171

Reflectance Spectra of Uranus, Neptune and Saturn-Moon Titan Spectroscopic Atlas for Amateur Astronomers

Na l 5890/96 Telluric O2 Telluric H2O Telluric O2 TABLE 92

Saturn-Moon Titan

Neptune (H2, He, CH4, NH3) NH3

CH4 CH4 CH4
CH4

CH4 CH4 CH4

CH4 CH4

Uranus (H2, He, CH4, NH3)

Hα 6562.82

Magnesium
Triplet
Hβ 4861.33

©Richard Walker 2014/02 172

Coma-Spectrum Comet C/2009 P1 Garradd (November 17, 2011, 1730 GMT) TABLE 94 Spectroscopic Atlas for Amateur Astronomers

C2 /CH 4383/85 C2 4737 Butane Torch

Swan Bands Air GlowO2 6300 / H2O

C3 CH 4315 Hg I 4358.34 telluric C2 4715 C2 5165 NH2/C2 Air Glow O2 5577 NH2/C2
C3 4056 C2 4685 C2 5130

CN 3880

P1 Garradd

C3 CH
C3 CN

CN C3 CN CH C2 C2 C2 C2 ©Richard Walker 2012/03

Influence zones of the individual NH2 NH2 NH2 NH2 173
molecule emission bands [210]

Spectroscopic Atlas for Amateur Astronomers 174

30 Telluric Molecular Absorption

Table 95: Overview on the most dominant absorptions caused by the earth’s atmosphere.

Between approx. λλ 6,200 – 7,700 it literally swarms with molecular H2O- und O2 absorp-
tion bands, caused by the earth’s atmosphere. Few of them appear in the form of discrete
lines even beyond λ 5,700, unfortunately pretending the presence of stellar absorptions.
On Table 95 the solar spectrum within the domain of λλ 6,800 – 7,800 is shown (900L
grating). These features appear here so impressively that Fraunhofer has labelled them with
the letters A and B. At that time he could not know that these lines do not originate from
the Sun, but arise due to absorption in the earth’s atmosphere.

For astronomers, they are only a hindrance, unless they need fine water vapour lines of
known wavelength to calibrate the spectra. These "calibration marks" are generated by
complex molecular vibration processes, appearing as a very broad scattered absorption
swarm. The atmospheric physicist deduces from the H2O absorptions moisture profiles of
the troposphere. The O2 bands (Fraunhofer A and B) allow him conclusions about the layer
temperatures of the atmosphere [180].

For the "average amateur" important is just the awareness, that the line identification
within this area requests great caution. In most of the cases only the Hα line overtops un-
ambiguously the “jungle” of the telluric absorption lines and bands. This is particularly the
case for the early spectral classes, where the maximum of the stellar radiation occurs in the
ultraviolet or blue part of the spectrum. Exceptions are here Wolf-Rayet and Be-stars and
those which show mass loss due to strong P Cygni profiles. In the latter two cases, at least
the helium line He l at λ 6678 can additionally be identified.

Stars of the late K and all M-classes, as well as the carbon stars, predominantly radiate in
the infrared part of the spectrum. Therefore particularly intense titanium oxide (TiO) absorp-
tion bands are capable to overprint these telluric lines. Further the reflection spectra of the
large gas planets show mainly here the impressive gaps in the continua of their spectral
profiles.

These telluric bands and lines can be reduced to a certain extent with a relatively large
effort – e.g. by subtraction of synthetically produced standard profiles of the telluric lines
(see Vspec manual) and further by comparison with profiles of standard stars.

Dazu eignet sich auch die Spektralklasse A0, welche in diesem Sektor nur wenige und sehr
schwache, stellare Linien zeigt. Very suitable for this purpose is the spectral class A0 which
shows just few and very weak stellar lines within this range.

Complicating facts are the influences by weather conditions, elevation angle of the object
etc. For further information refer to [180], [181]. Moreover, there is a highly recommended
freeware program by Peter Schlatter, which allows the almost complete extraction of H2O
lines [554].

Table 95A: Telluric H2O absorptions around the Hα line

These H2O lines (Vspec database) are useful for the calibration of high-resolution spectra
particularly around the Hα line. As an orientation aid these are shown at two highly re-
solved spectral profiles (R~20,000) with different spectral classes – δ scorpii, B0.3 IV and
the Sun, G2V, recorded with the SQUES Echelle spectrograph [600].

Tafel 95B: Telluric O2 absorptions of the Fraunhofer A- and B-Band

Highly resolved profiles, recorded with the SQUES Echelle spectrograph [600]. The line
identification and the according wavelengths are based on [182].

Most significant spectral absorptions due to the earth atmosphere Spectroscopic Atlas for Amateur Astronomers

Fraunhofer B H2O Absorption Fraunhofer A TABLE 95
O2 Absorption O2 Absorption

7594 – 7684

6867 – 6944 7168 - 7394
I= –0.2

©Richard Walker 2010/05 175

Spectroscopic Atlas for Amateur Astronomers 176

TABLE 95A 6612.53 ©Richard Walker 2012/12

6605.92
6602.4
6599.324

6594.361

6588.59
6586.596

6583.6
6580.786

6574.847
6572.072

6568.806
Hα
Telluric H2O Absorptions at Hα Line 6564.196

Recorded with the SQUES Echelle Spectrograph 6561.106
Sun G2V 6560.499
δ scorpii B0.3 IV
6558.149
Hα 6557.171

6553.785
6552.629

6548.622
6547.705

6545.781

6543.907
6542.313

6536.72

6534
6532.359
6530.598

6523.656

6519.45
6516.57

6514.74
6512.01
6508.59

6504.22

6497.56

6495.86
6494.39 6492.92
6490.79
6489.13

6488.04

Spectroscopic Atlas for Amateur Astronomers 177

TABLE 95 B K I 7698.979 H2O/O2 ©Richard Walker 2012/12
H2O
7696.868 H2O
7695.836
H2O/O2
7690.217
7689.177 H2O

Telluric O2 Absorptions: Fraunhofer A and B SQUES Echelle Spektrograph 7683.800 6924.1 64
7682.756 6923.286
According: Fine Structure of the Red System of Atmospheric Oxygen Bands, H. D. Babcock and L. Herzberg
7677.618 6919.002 δ Scorpii: Fraunhofer B Band O2 Absorption
Sun: Fraunhofer A Band O2 Absorption 7676.563 6918.122

7671.670 6914.090
7670.600 6913.200

7665.944 6909.431
7664.872 6908.534

7660.454 6905.023
7659.370 6904.117

7655.182 6900.868
7654.094 6899.954

7650.135 6896.965
7649.035 6896.037

7645.312 6893.309
7644.200 6892.369

7640.707 6889.903
7639.585 6888.948

7636.3 28 6886.743
7635.192 6885.754
6883.833
7632.168
7631.016 6879.928
7628.225 6879.0 41
7627.054
7624.500 6877.637
7623.288 6876.715
7620.996 6875.59 0
6874.653
Ni I 7619.21 6873.798
6872.247
7616.146 6872.843
7615.061 Blend

7613.194 6869.887
7612.060
Blend
7610.455 Blend
7609.302

7607.933
7606.767

7605.635
7604.453

7603.5 56
7602.346

7601.697

Blend

7597.438

Blend
7595.235
Blend 7594.507

Spectroscopic Atlas for Amateur Astronomers 178

31 The Night Sky Spectrum

31.1 Introduction

Mainly due to light pollution and airglow the night sky is significantly brightened and the
astronomical observations thereby seriously hampered.

The light pollution is mainly caused by street lamps and other terrestrial light sources. The
light is chiefly scattered by molecules and particles in the Mesopause (altitude approx. 80 –
100km).

The airglow is produced during the day in the atmosphere by photoionisation of oxygen as a
result of solar UV radiation and chemical reaction chains. At night recombination takes
place, causing emission lines at discrete frequencies. Really striking here are only two of
the O I lines at λλ 5577.35 and 6300.23. The latter is visible just under a very good night
sky, and therefore lacking in the spectrum of Table 96. Airglow however includes also the
rotational and vibrational bands of OH molecules in the near infrared range, detected in
1950 by A. B. Meinel. Further influence, particularly over the continuum of the night sky
spectrum, has the diffuse galactic light (DGL), the integrated starlight (ISL) and the re-
flected zodiacal light (ZL). The latter may also contribute elements of the solar spectrum.
(www.caltech.edu)

31.2 Effects on the Spectrum

Depending on the quality of the night sky, at long to very long exposure times the emissions
of airglow and light pollution can disturbingly superimpose the recorded signal of the exam-
ined object, example see M1, Table 86 and 96. The effects of airglow to the spectrum are
much less harmful than the light pollution, which can consist of dozens of emission lines,
depending on the type of terrestrial light sources in the wider surroundings, as well as me-
teorological factors. Under a perfect night sky, only the airglow is visible in the spectrum.

31.3 Countermeasures

For long term exposures of two-dimensional appearing objects like nebulae, helps the re-
cording of the night sky spectrum in the immediate vicinity of the examined object (with the
same exposure time). This must then be subtracted from the object spectrum, eg with Fits-
work. For point-like appearing objects, the light pollution can be subtracted together with
the sky background (eg IRIS).

31.4 Comments to Table 96

This night sky spectrum was recorded to clean the disturbed spectrum of M1 (Table 86). It
was taken at my home (Rifferswil Switzerland) about 610m above sea level, under a rather
moderately good rural sky with a limiting magnitude of about 4–5m and an elevation angle
of approximately 50°. For such long exposures (30 Minutes) the C8 was equipped with a
long dew cap to reduce the influence of scattered light from the surrounding area. The
lighting of the residential area consists of gas discharge lamps, of which some but not all
spectral lines appear in the spectrum. Major roads with sodium vapour lamps are some
100m distant without a direct line of sight. As the most harmful source of pollution in litera-
ture consistently high-pressure sodium vapour lamps are referred, since they produce a
bell-shaped emission around the Fraunhofer D Lines λ 5890/96 D (see also Table 104).
This feature can hardly be effectively filtered out without impairing of the wanted signal.
Not surprisingly the famous sky contamination act („La Ley del Cielo“), affecting the islands
of Tenerife and La Palma, severely limits the use of high-pressure sodium vapour lamps
[190]!

Spectroscopic Atlas for Amateur Astronomers 179

TABLE 96 Richard Walker 2010/05©

Night Sky Spectrum OH Meinel Bands: Molecular
Rifferswil Switzerland Rotational- and Vibrational Bands

Na I 6154/65
6115 Ar II / Xe II

Na I 5890/96 High-Pressure
HG I 5790 Sodium Vapor
HG I 5770
M1 Spectrum + ?
Light Pollution Na I 5683/88
M1 Spectrum
[O I] 5577.35 Airglow

Hg I 5460.75
Xe II 5419.15

O2 Lines [O I] 4802 ?

Hg I 4358.34

Spectroscopic Atlas for Amateur Astronomers 180

32 Terrestrial Light Sources

32.1 Spectra of Gas Discharge and Calibration Lamps

Gas discharge lamps play a key role for astronomers. They can be useful, for example to
calibrate the spectral profiles - but also represent a disturbing source e.g. by light pollution
from the road- and municipal lighting. For beginners they are also useful exercise objects to
study the spectra – particularly during cloudy nights. Further spectra and info to calibration
light sources see [32], [34], [35], [508].

Unfortunately, gas discharge lamps are operated with relatively high voltage. This requires,
especially for outdoor operation, ie minimal electrical knowledge of relevant safety meas-
ures such as isolation transformers, GFCI devices, or DC/AC Power Inverters (ie 12V
DC/230V AC).

Table 101: Neon glow lamps

The orange glowing neon glow lamps are used as indicator lights, e.g. for stoves, flat irons,
connection plug boards etc. They produce a large number of emission lines, mainly in the
red region of the spectrum. Their wavelengths are known with high accuracy. These proper-
ties make them very popular as calibration lamps among the amateurs. The disadvantage is
that the intense lines are limited to the red region of the spectrum. Further they can only be
operated with mains voltage of 230V, therefore posing a safety risk and requiring specific
electrotechnical safety measures. With very long exposures, especially in the green area
further emissions will appear, but coupled with the disadvantage that the most intense
neon lines in the red range of the spectrum become oversaturated at low to moderately
high-resolution spectrographs. Such lines can therefore no longer be used for calibration
purpose within the same profile. For the calibration of broadband spectra (red to blue) or
higher-resolved profiles within the blue range, low cost solutions according to Tables 106 –
108, or even better [35] are preferred. In the professional sector or on the senior amateur
level, relatively expensive hollow cathode lamps are used, producing a fine raster of eg
iron-argon or thorium emission lines.

Table 102: Energy saving lamp ESL Osram Sunlux

Amateurs often use ESL as a complement to the neon lamps, which are limited to the red
part of the spectrum. These lamps contain several gases and substances performing differ-
ent tasks – among other things, fluorescent substances, usually so called rare earth metals.
The mixture depends largely on the colour, the lamp should produce. Anyway for calibration
purposes useful are only the intense lines of the auxiliary gases, e.g. Argon (Ar), Xenon (Xe),
and Mercury (Hg). Unfortunately, some of these line positions are located very close to-
gether and are therefore difficult to distinguish, such as Ar II (6114.92) and Xe (6115.08).

Table 103: Xenon strobe tube

Better-suited for the broadband calibration of profile graphs, is the spectrum of a xenon
strobe light, e.g. kit K2601 from Velleman. This kit is designed primarily as position lamp
for model aircraft as well as for lighting effects on stages, dance floors, in shop windows
etc. The flicker frequency for the calibration purpose must be adjusted to the maximum and
the lamp requires some 15 seconds warmup time to produce accurately the specified lines.
This lamp generates some 50 useful lines, distributed over the entire range from the near
infrared to violet (about λλ 8,000 – 3,900). In the infrared domain further emissions are
available, but not documented here. Most emission lines are produced by xenon. However
the shortwave-end of the spectrum is dominated by lines of rare earths. The xenon tube
gets very hot during operation. Further it requires also mains voltage of 230V. Therefore an
appropriate housing is needed.

Spectroscopic Atlas for Amateur Astronomers 181

Table 104: High pressure sodium vapour lamp for street lighting

This lamp is widely used for street lighting. The sodium generates light in the domain of the
Fraunhofer D1, and D2 line. Due to the high gas pressure it’s not a real monochromatic
light. The continuum, as a result of pressure and collision broadening, as well as self ab-
sorption effects, shows a bell-like shape. Added auxiliary gases, for example Xenon, can
produce some discrete lines in the spectrum.

Table 105: High power Xenon lamp

Such high pressure gas discharge lamps are used for lighting of stadiums, position lamps
on mountain tops etc.

The line identification in Table 102 – 108 is based on Vspec (Tools/Elements/elements), as
well as on data sheets from the lamp manufacturers.

Table 106: Glow Starter ST 111 from OSRAM, (4–80W, 220V–240V)

Another alternative for broadband calibration and detailed analysis in the blue range of
spectra are modified glow starters for fluorescent lamps. They contain a small gas dis-
charge lamp, which is not used there as light source but as a bimetal switch. For our special
purpose it must be wired with a series resistor (details see [34]). OSRAM declares the
composition of the gas with hydrogen H and argon Ar. The light output in the blue range of
the spectrum is relatively weak and may require somewhat longer exposure times. For
110V mains, appropriate starters may be used also from other suppliers. The necessary se-
ries resistors must be determined by tests. The current must be limited to the extent, that a
reasonable light output is achieved without closing the bimetal switch. In the case of
ST111 40-80W, ~24 kΩ was evaluated. Rainer Ehlert from Mexico tested the 110V type
“Fulgore” and evaluated the same resistor value!

Table 107:

Glow starter RELCO SC480, in addition to argon and hydrogen, contains also neon and he-
lium. Thus in the optical spectral calibration about 270 lines are available, which is even
sufficient for the calibration of high-resolution Echelle spectra. An according line atlas, re-
corded with the DADOS- and SQUES spectrographs, can be found in [35]. Caveat: The
Model RELCO SC422 (110V) contains Argon only!

Table 108: Glow starter Philips S10

Contains neon and xenon. These elements form many blends in the red part of the spec-
trum. In the blue part appear some intensive lines, generated by dopants and alloy materi-
als.

Practial note to the calibration in order to avoid transmission errors:

If data from any table of this atlas are used for wavelength calibration, they can be copied
with ctrl c from the pdf file and transferred to the Vspec calibration field with shift insert.

Spectrum Neon Glow lamp Spectroscopic Atlas for Amateur Astronomers

5852.49 7032.41 TABLE 101
5881.89

5944.83
5975.53
6030.00

6074.34

6096.16 6929.47 7245.17 8082.46
6143.06 7173.94 8136.41

6163.59 7535.77
6217.28 7488.87
6266.49 7438.90

6304.79

6334.43

6382.99

6402.25
6506.53

6532.88

6598.95

6678.28

6717.04

©Richard Walker 2010/05

182

Spectroscopic Atlas for Amateur Astronomers 183

TABLE 102

Spectrum ESL Osram Sunlux

Spectroscopic Atlas for Amateur Astronomers 184

TABLE 103 Xe 8061.34

Xe 6182.42 Xe 7967.34
Xe 7887.4
Spectrum of the Xenon Strobotube 27 WS Kit: Velleman K2601 Xe 6097.59
Xe 6051.15 Xe 7642.02
Lines lacking wavelength
indications are not fit for Xe 6036.2 Xe 7393.79
calibration purposes Xe 7284.34
Xe 5976.46
©Richard Walker 2010/07 Xe 5934.17 Xe 7119.6 Xe 6976.18
Xe 5893.29 Xe 6882.16
Xe 5875.02 Xe 6827.32
Xe 6728.01
Xe 5824.8 Xe 6668.92
Xe 6595.01
Xe 5751.03
Xe 6469.7
Xe 5699.61
Xe 5667.56 Xe 6318.06
Xe 5616.67 Xe 6182.42

Xe 5531.07 Xe 4843.29
Xe 4807.02 Xe 4828.04
Xe 5472.61
Xe 5460.39 Xe 4734.15
Xe 5438.96 Xe 4673.7

Xe 5419.15 4624.9 Ce?
Xe 5372.39 4525.31 La?
Xe 5339.33
4501.52 Cs?
Xe 5292.22
Xe 5261.95 4384.43 Cs?

Xe 5191.37 4193.8 Ce?

Xe 5125.7 4080 Ce?
Xe 5080.62
Xe 5028.28 3952.54 Ce?
Xe 4988.77
Xe 4971.71

Xe

Spectroscopic Atlas for Amateur Astronomers 185

TABLE 104

High pressure sodium vapor lamp

Xenon high power lamp Spectroscopic Atlas for Amateur Astronomers
Position lamp on the summit of Mt. Rigi
TABLE 105
Xe: Xenon
Y: Yttrium fluorescence material
Zr : Zirconium (Getter material)
Tm: Thulium (activation of the luminescent substance)
Dy: Dysprosium (color optimization emission spectrum)
Ne: Neon
Sc: Scandium (color optimization emission spectrum)

186

Spectroscopic Atlas for Amateur Astronomers 187

Spectrum Glow Starter OSRAM ST 111 4-80W Grating: 900L/mm TABLE 106 Blend
Grating: 200L/mm Ar 7635.11
Ar 4764.78 Blend
Richard Walker 2011/07©
Ar 4735.91 Ar 7383.98
Ar 4726.87
Ar 7272.94
Ar 4657.9
Ar 7067.22 Ar 7147.04
Ar 4609.57 Ar 6965.43 Ar 6871.29
Ar 4589.89
Ar 6752.83
Ar 4579.35
Ar 4545.05 Ar 6677.28
Hα 6562.85
Ar 4510.73
Ar 6416.31
Ar 4481.81
Ar 4474.76 Ar 6172.28
Ar 4448.88 Ar 6032.13

Ar 4426.0 Ar 5606.73
Ar 4400.99 Ar 5495.87

Ar 4379.67 Hβ Ar 4965.08
Ar 4370.75 4861.33 Ar 4806.02
Ar 4348.06 Ar 4764.87

Hγ 4340.47 Ar 4657.9
Ar 4609.57
Ar 4300.1 Ar 4545.05 Ar 4510.73
Ar 4277.53
Ar 4259.36 Blend

Ar 4237.22 Blend
Ar 4228.16 Ar 4277.53
Blend
Ar 4190.71 Ar 4200.67
Ar 4158.59 Ar 4158.59
Ar 4131.72
Ar 4072.0
Ar 4103.91 Blend
Blend mit Hδ
Ar 4072

Ar 4052.9
Ar 4042.89

Ar 4013.86
Ar 3994.79
Ar 3979.36

Blend
Ar 3928.6

Spectroscopic Atlas for Amateur Astronomers 188

Spectrum Glow Starter RELCO 480 4-80W 220-250 Grating: 200L/mmTABLE 107 Blends
©Richard Walker 2012/09
Ar 7067.22 Ar 7147.04

Ar 6965.43 Blend

Ne 6929.47
Ar 6871.29

Ar 6677.28 Ar 6752.83
Ne 6717.043

Ne 6598.95
Hα 6562.85

Ne 6506.53 Ne 6532.88

Ne 6402.25 Ne 6382.99
Ne 5852.48 Ne 6334.43
Ne 6304.79

Ne 6266.49

Ne 6217.28

Ne 6143.06 Ne 6163.59

Ne 6096.16
Ne 6074.34
Blend

Blend Blend

Blend

Ne 5764.41

Ar 5606.73
Ar 5558.70
Ar 5495.87

Ne 5400.56

Ar 5187.74

Blend
Ar 4965.08

Ar 4879.86

Ar 4764.87 Ar 4806.02
Blend

Ar 4657.9

Ar 4609.57 Blend

Ar 4545.05
Ar 4510.73
Blend

Ar 4426.00

Blend Blend
Ar 4300.1
Ar 4277.53

Ar 4200.67 Blend

Ar 4158.59 Ar 4131.72
Blend

Ar 4072.0
Blend

Ar 3946.1
Blend

Ar 3850.58

Spectroscopic Atlas for Amateur Astronomers 189

TABLE 108

Ne 7032.41
Ne 6929.467
Spectrum Glow Starter Philips S10 Grating: 200L/mmNe 7245.17
©Richard Walker 2014/01
Ne 6717.04 Blend
Ne 6678.28 Xe 7119.6

Blend Blend

Xe 6512.83 Ne 6030.0
Ne 5764.41
Blend
Ne 6334.43
Xe 6270.82

Blend
Blend

Blend

Ne 5852.48

Xe 5401.0
Xe 5339.33
Xe 5292.22

Xe 5260.44
Xe 5191.37

Xe 4916.51
Xe 4843.29

Xe 4807.02
Xe 4734.15

Xe 4462.19
Xe 4330.52

Xe 4213.72

Spectroscopic Atlas for Amateur Astronomers 190

32.2 Spectra of Gas Flames

Table 110: Swan Bands in comparison to the following spectra:
butane gas torch, comet Hyakutake and carbon star WZ Cassiopeiae

The Swan Bands, already described in sect. 23, are of great importance for astrophysics.
They are generated e.g. in the cool atmospheres of carbon stars as absorption bands and in
the comets of the solar system as emission bands. Molecular band spectra are generated
by complex rotational and vibrational processes of heated molecules [3]. The required exci-
tation energy to generate Swan Bands is relatively low. Therefore this spectral detail can be
easily simulated by the intense combustion of hydrocarbons with do it yourself equipments
from the hardware store!

Table 110 shows the Swan Bands, generated with a butane torch. The wavelengths of the
most intensive band heads are λλ 6191, 5636, 5165, 4737 and 4383. Further a number of
fainter C2 absorptions are still recognisable, with wavelengths according to [110]. Some of
these lines are also visible in the profiles of the carbon stars in Table 64.

In this table, spectra of the butane gas flame (C4H10), comet Hyakutake and the carbon star
WZ Cassiopeiae (excerpt from Table 64) are superposed. The shape of the Hyakutake pro-
file (March 28, 1998) was transferred to and accordingly scaled up in the drawing from an
ESO/Caos project http://www.eso.org/projects/caos/.

Striking are the amazingly similar emission spectra of the comet Hyakutake and the butane
gas flame within the domain of the C2 Swan bands! That’s why for both cases the same
physical process is taking effect. WZ Cassiopeiae shows the Swan Bands in absorption in-
stead of emission. Therefore the shape of this profile runs inversely to the others.

The line identification is based amongst others on [110], [210].

Tests with acetylene flames (C2H2), carried out in the workshop of Urs Flükiger, yielded
similar results (Photo below).

Spectroscopic Atlas for Amateur Astronomers 191
C2 6191
TABLE 110 Butane
torch
Swan Bands: Butane torch, Comet Hyakutake and WZ Cas
Richard Walker 2010/05©
WZ Cassiopeiae
carbon star C2 5636
C2 5585
C2 5541
C2 5502

C2 5165
C2 5130

Comet HyakutakeCCCC2222 4737
4715
Swan Bands4698
4685

C2 /CH 4383/85
CH 4315

CH 3900/3880

Spectroscopic Atlas for Amateur Astronomers 192

32.3 Spectra of Terrestrial Lightning Discharges

Already since the beginning of the Spectroscopy in 19th century it was attempted to gain
spectra of lightning discharges. At the beginning of the 20th Century, also well-known as-
tronomers have been involved, like Pickering and Slipher [708]. Further information and
references see also [33].

The following figure shows the spectrum of a lightning that has hit the ground in a distance
of approximately 220 m from the observer. Martin Huwiler filmed this event through the
closed window pane with a Canon G1X and a 300L mm-1 transmission grating, mounted in
front of the camera lens.

Table 111: Lightning spectrum recorded via cloud reflection

For this, the C8 telescope with the DADOS spectrograph and the Atik 314L+ was built up at
night in the living room. It pointed through the closed window on the approaching thunder-
storm at the western horizon. Three shots of each 180 seconds in the 2x2 binning mode
have been processed. Per image the integrated light of some 5-10 lightning discharges
could be recorded. Since the cloud base was very low, on all shots the light pollution had to
be subtracted.

The idea to gain lightning spectra this way, originates from none other than Vesto M.
Slipher. With the same intention, he directed on the evening of July 24 1917 his spectro-
graph at the Lowell Observatory in Flagstaff to a thunderstorm, which raged in a distance of
about 10 km above the south slopes of the San Francisco Peaks [708].

Striking here is the very intense CN emission at approximately λ 3900. According to [707]
this is a characteristic feature for discharges with relatively long-lasting currents, generated
mainly by the type of "Cloud-to-Ground Lightning and causing a high fire risk. Therefore in
the 1980ies, it was even discussed in the U.S. to detect this spectral feature with satellites,
as an early warning criterion for possible forest fires [707]. Anyway on all my shots, with
the integrated light of several lightning strikes, this CN emission appeared in comparable
intensity.

Otherwise, most of the lines of the lightning spectrum are rather complex, broad blends of
OII, NII, OI, NI as well as emissions of the H-Balmer series. The raw profile is wavelength
calibrated only.

Spectroscopic Atlas for Amateur Astronomers 193

Lightning Cloud ReflectionTABLE 111 O I 7157

C8, DADOS: Grating 200L mm-1, Slit width 25μm 4.8.2012Hα 6562.83O II 6721.35
Atik 314L+ -2°C, 3x180s, 2x2 Binning (ca. 30 Lightning strokes)O II 6640.9

©Richard Walker 2012/08N I 6482 - 84
N I 6441 - 57

O I 6156- 58 OI

N I 6008

N II

NI

N I / N II
N II 5670- 90
N I 5616- 23

N I 5560- 64

N II / OI

N II 5171 -99

N II 5001 - 07
N I 4915

Hβ 4861

N II/O II

N I / O II
Hγ / N I / O II

N I / N II / OI

Hδ /N II / O II N II 4041 - 44

O II 3910 - 26 N II 3995 OI

CN 3871 ?

Spectroscopic Atlas for Amateur Astronomers 194

33 Spectral Classes and ‫ – ܑ ܖܑܛ ܞ‬Values of Important Stars

Stars of the spectral classes O, B, A, F, G, K, M observable from Central Europe:

Spectral Luminosity Appar. ‫ ݒ‬sin ݅ Bayer desig- Proper
class class magn [km/s] nation name

O8 III 3.5 130 λ Ori A Meissa
09 lll 2.8 ι Ori Nair al Saif
O9.5 lb 2.1 94 ζ Ori A Alnitak
ll 2.2 δ Ori A Mintaka
V 3.7 σ Ori A

B0 la 1.7 87 ε Ori Alnilam
B0.5 lVe 2.5 300 γ Cas
V 2.8 24 τ Sco Saiph
B1 la 2.1 82 κ Ori Dschubba
B2 lV 2.3 181 δ Sco Acrab
B3 V 2.6 Adid
B5 lV 2.9 β Sco Algiebbah
B6 V 3.4 153 ε Per Spica B
B7 V 1.0 46 η Ori Mirzam
B8 ll-lll 2.0 159 α Vir Menkib
lb 2.9 36 β CMa Alfirk
B9 lll 3.2 59 ζ Per Bellatrix
lll 1.6 28 β Cep Algenib
lV 2.8 59 γ Ori Nunki
lV 2.0 3 γ Peg Segin
lV 3.4 201 σ Sgr Aludra
la 2.5 19 ε Cas
llle 3.0 45 η CMa Aldhibah
lll 3.2 259 δ Per Electra
lll 3.7 31 ζ Dra Merope
lVe 4.2 215 17 Tau Regulus
V 1.4 282 23 Tau Alnath
lll 1.7 329 α Leo Alcyone
llle 2.9 71 β Tau Sheliak
IIpe 3.4 215 η Tau Rigel
la 0.1 Algol
V 2.1 β Lyr Gienah Corvi
lllp Hg Mn 2.6 33 β Ori Gomeisa
Ve 2.9 65 β Per Maia
lll 3.9 41 γ Crv Atlas
lll 3.6 276 β Cmi Albireo B
Ve 39 20 Tau
lll 3.2 212 27 Tau Alpheratz
IVp Mn Hg 2.1 Sulafat
lll 3.2 β Cyg
68 φ Sgr
56 α And
76 γ Lyr

Spectroscopic Atlas for Amateur Astronomers 195

Spectral Luminosity Appar. ‫ ݒ‬sin ݅ Bayer des- Proper
class class magn [km/s] ignation name
A0
Va 0.0 15 α Lyr Vega
A1 p Cr 1.8 38 ε UMa Alioth
lV 1.9 32 γ Gem Alhena
A2 Vm -1.46 13 α CMa A Sirius A
V 1.9 Castor A
A3 V 2.4 α Gem A Merak
V 3.8 39 β UMa Albali
A4 la 1.25 96 ε Aqr Deneb
A5 Vm 2.9 21 α Cyg Castor B
lV 1.9 Menkalinan
A7 V 2.1 α Gem B Denebola
lll-lV 2.8 37 β Aur Zubenelgenubi
A9 V 3.4 121 β Leo Heze

lV 2.6 α Lib A Zosma
V 2.6 173 ζ Vir Sharatan
lll 2.1 181 δ Leo Ras Alhague
lll-lV 2.7 79 β Ari Ruchbah
V 0.8 219 α Oph Altair
V 2.4 113 δ Cas Alderamin
lll 3.0 242 α Aql Seginus
lll 3.8 246 α Cep
139 γ Boo
141 γ Her

F0 lae 3.0 29 ε Aur A Alanz
lll Adhafera
lV 3.4 84 ζ Leo Wasat
V Porrima
3.5 111 δ Gem Caph
F2 lll-lV Procyon
F5 lV-V 2.8 γ Vir Mirfak
Polaris
lb 2.3 70 β Cas Mothallah
lb-ll Wezen
F6 lV 0.4 6 α CMi Sadr
F8 la Zavijah
lb 1.8 18 α Per
V
2.0 17 α Umi

3.4 93 α Tri

1.9 28 δ CMa

2.2 20 γ Cyg

3.6 3 β Vir

G0 lV 2.7 13 η Boo Muphrid
lb 2.9 18 β Aqr Sadalsuud
lll 0.1 α Aur Capella B
3.0 <17 ε Leo Raselased
G1 ll -26.75 1.9 SOL Sun
G2 V -0.27 α Cen A Rigil Kentaurus
2.8 13 β Dra A Rastaban
V 3.0 <17 α Aqr Sadalmelik
lb-lla 2.7 <17 β Crv Kraz
lb 0.1 α Aur A Capella A
G5 ll 2.8 <19 β Her Kornephoros
lll3e
G7 llla

Spectroscopic Atlas for Amateur Astronomers 196

Spectral Luminosity Appar. ‫ ݒ‬sin ݅ Bayer des- Proper
class class magn [km/s] ignation name
G8 Mebsuta
lb 3.0 <17 ε Gem
G8 lll Fe l 3.5 <19 δ Boo Nekkar
3.5 <17 β Boo Vindemiatrix
IIIa Ba0.3 Fe-0.5 2.8 <17 ε Vir

lllab

K0 lllb 1.1 <17 β Gem Pollux
llla
K1.5 llla 1.8 <17 α Uma Dubhe
K2 ll - lll
K3 III Fe-0.5 2.2 21 α Cas Shedar
K4 III Ca-1
K5 IIIb CN1 2.4 ε Boo Izar
K7 lll
IIIa -0.0 <17 α Boo Arcturus
ll
ll 2.0 <17 α Ari Hamal
lll
III Ba0.5 2.7 <17 α Ser Unukalhai
lll
lll 2.8 <17 β Oph Cebalrai
V
lllab 2.7 δ Sgr Kaus Media
V
2.7 <17 γ Aql Tarazed

3.1 β Cyg A Albireo A

2.1 <17 β Umi Kochab

3.5 <17 β Cnc Altarf

0.9 <17 α Tau Aldebaran

2.2 <17 γ Dra Eltanin

5.2 <2 61 Cyg A

2.2 α Lyn Alsciaukat

6.1 <2 61 Cyg B

M0 llla 2.1 <20 β And Mirach
M0.5 lll 3.1 μ Uma Tania Australis
M1.5 lll 2.7 δ Oph Yed Prior
M1-2 la-lb 1.0 α Sco Antares
M3 llla 2.4 β Peg Scheat
Ia-Iab 0.5 α Ori Betelgeuse
M5 lll 2.5 α Cet Menkar
M7 lll 3.3 η Gem Propus
lllab 2.9 μ Gem Tejat Posterior
lll 3.4 δ Vir Auva
lb - ll 3.1 α Her Ras Algethi
llle 3-10 ο Cet Mira (variable)

Lower case letters of the Greek alphabet

α Alpha η Eta ν Ny τ Tau
β Beta θ Theta ξ Xi υ Ypsilon
γ Gamma ι Iota ο Omikron φ Phi
δ Delta κ Kappa π Pi χ Chi
ε Epsilon λ Lambda ρ Rho ψ Psi
ζ Zeta μ My σ Sigma ω Omega

Spectroscopic Atlas for Amateur Astronomers 197

34 Required Ionisation Energies for the Individual Elements

This table shows the required energies [eV], which are needed for the ionisation of a cer-
tain element, starting from the ground state ݊ = 1. Source: [201].

Z Ele- Required excitation energy [eV] to reach the following ionisation stages

ment ll lll lV V Vl Vll Vlll lX

1H 13.6

2 He 24.6 54.4

3 Li 5.4 75.6 122.5

4 Be 9.3 18.2 153.9 217.7

5 B 8.3 25.2 37.9 259.4 340.2

6C 11.3 24.4 47.9 64.5 392.1 490.0

7N 14.5 29.6 47.5 77.5 97.9 552.0 667.0

8 O 13.6 35.1 54.9 77.4 113.9 138.1 739.3 871.4

9F 17.4 35.0 62.7 87.1 114.2 157.2 185.2 953.9

10 Ne 21.6 41.0 63.5 97.1 126.2 157.9 207.3 239.1

11 Na 5.1 47.3 71.6 98.9 138.4 172.2 208.5 264.2

12 Mg 7.6 15.0 80.1 109.2 141.3 186.5 224.9 265.9

13 Al 6.0 18.8 28.4 120.0 153.7 190.5 241.4 284.6

14 Si 8.2 16.3 33.5 45.1 166.8 205.1 246.5 303.2

15 P 10.5 19.7 30.2 51.4 65.0 230.4 263.2 309.4

16 S 10.4 23.3 34.8 47.3 72.7 88.0 280.9 328.2

17 Cl 13.0 23.8 39.6 53.5 67.8 98.0 114.2 348.3

18 Ar 15.8 27.6 40.7 59.8 75.0 91.0 124.3 143.5

19 K 4.3 31.6 45.7 60.9 82.7 100.0 117.6 154.9

20 Ca 6.1 11.9 50.9 67.1 84.4 108.8 127.7 147.2

21 Sc 6.5 12.8 24.8 73.5 91.7 111.1 138.0 158.7

22 Ti 6.8 13.6 27.5 43.3 99.2 119.4 140.8 168.5

23 V 6.7 14.7 29.3 46.7 65.2 128.1 150.2 173.7

24 Cr 6.8 16.5 31.0 49.1 69.3 90.6 161.1 184.7

25 Mn 7.4 15.6 33.7 51.2 72.4 95.0 119.3 196.5

26 Fe 7.9 16.2 30.7 54.8 75.0 99.0 125.0 151.1

27 Co 7.9 17.1 33.5 51.3 79.5 102 129 157

28 Ni 7.6 18.2 35.2 54.9 75.5 108 133 162

29 Cu 7.7 20.3 36.8 55.2 79.9 103 139 166

30 Zn 9.4 18.0 39.7 59.4 82.6 108 134 174

31 Ga 6.0 20.5 30.7 64