Absorption spectra of neutral interstellar clouds

Absorption spectra of neutral interstellar clouds

Absorption spectra of neutral
interstellar clouds
Jacek Krełowski
Center for Astronomy, N. Copernicus University
Gagarina 11, Pl-87-100 Toruń
email: [email protected]
Interstellar absorptions
Extinction
Polarization Atomic
lines
E(λ-V)
E(B-V)
Curve
1 max
Only
Simple
resonance species
Diffuse
interstellar
bands
The oldest
puzzle
R= AV
E(B-V)
Nonadditive
Doppler
effect
Free
radicals
380 known
DIBs
Variety
Scarce data
Ions as
distance
Formation
Various
profiles
Dust grains
Grain
Their surfaces orientation
Molecular
bands
Depletions Abundance Molecular
ratios
carriers?
Sources of information on ISM
Visual range
Ultraviolet
Infrared
Radio
Cosmic
radiation
Extinction
polarization
Extinction
Continuous
emission
Line HI
21 cm
Chemical
composition
Lines, bands, Rezonance
DIBs
lines
Bands of
ices
High HI
series
Soft X-ray
background
Images of
galaxies
Bands of
H2 and CO
Molecular
bands
Molecular Accleration
mechanisms
bands
Reflection
nebulae
Bands of OH R=Av/E(B-V)
and NH
Embedded
stars
Ionization of
dark clouds
Schematic extinction curve
Variety of observed extinction curves
Effects of Sp +/- ½ subtype mismatch
Continuous extinction
Sum of the proceses of absorption (heating
of dust grains) and of scattering on dust
grains
Investigations possible till the Lyman jump
from the UV side
Energy re-emission in infrared
Origin and properties of dust grains
Late type stars, carbon and oxygen ones,
substantial mass loss
Infrared excess in spectra of the above
mentioned stars
Clouds as traps for dust particles
accelerated by stellar radiation fields
Various origin of elements found in
meteorites
„Stationary” „K” & „H” lines in spectroscopic binary oPer;
line „K” discovered by Hartmann - 1904, ApJ, 19, 268 in
spectrum of δ Ori; earlier seen in Nova Per 1901
2004/02/09
1.0
Relative intensity
2004/02/08
+
CH
0.8
0.6
HD 23180
1.7A
BOES
0.4
K
H
3940
3960
Wavelength (A)
3980
„H” line of the same doublet; orbital period of oPer is 4.5 days.
To the red – bottom of one of the Balmer lines of HI
Spectra of R=120,000 from Terskol echelle spectrometer
Relative intensity
1.0
HD 23180; 25 and 28 Oct. 2001
0.8
0.6
H
3969
3972
Wavelength
3975
Sodium doublet: „D1” i „D2” discovered by Miss Heger
in 1919 using panchromatic photographic emulsion
1.05
2004/02/09
Relative intensity
2004/02/08
0.70
2.4A
0.35
HD 23180
BOES
0.00
5870
5880
5890
Wavelength (A)
5900
Ultraviolet, usually non-saturated coublet of NaI;
note evident Doppler splitting (UVES R=80,000)
Relative intensity
1.5
HD 90177
1.0
HD147889
0.5
NaI
3301
3302
3303
Wavelength
3304
Neutral potassium (KI) doublet heavily
contaminated by telluric lines
Kalium dublet in the Terskol, R=120,000, spectrum of λCep
Relative intensity
0.9
0.6
0.3
KI
KI
7660
7680
Wavelength
7700
KI doublet exclusively well separated from the telluric features;
spectra from BOES, R=90,000.
HD 23180
Relative intensity
1.2
HD 208501
0.6
Potassium doublet in the spectra of two reddened stars
0.0
7670
7680
Wavelength
7690
7700
Profiles of the red KI line and UV NaI one are clearly
identical in the radial velocity scale
0.9
KI 7699 A
Relative intensity
NaI 3302 A
0.6
HD 90177
UVES R=110,000
80,000
0.3
-60
-30
0
30
Radial velocity
60
90
Rarely observed weak KI doublet clealry seen in high
resolution spectra (R=220,000) - ESO spectrograph CES
HD149757
Relative intensity
1.020
1.005
HD148184
0.990
0.975
4043
4044
4045
4046
Wavelength
4047
4048
KI interstellar line observed in two resolutions;
spectra from Terskol Observatory (Maestro spectrograph)
Relative intensity
1.0
R=45,000
0.8
R=120,000
0.6
IS KI
0.4
7698
7699
Wavelength
7700
Rarely observed lines of interstellar iron
Neutral iron interstellar lines in HD 23180
FeI 3859.913 A
1.05
Relative intensity
R=120,000
Terskol Obs.
1.00
0.95
FeI 3719.937 A
-60
-30
0
30
Radial velocity
60
Weak and rarely observed CaI interstellar line;
loosely related to color excess (Maestro R=120,000)
HD 23180 E(B-V)=0.26
1.02
Relative intensity
HD207198 E(B-V)=0.54
0.96
0.90
4225
4226
4227
Wavelength
4228
4229
Extremely weak doublet of interstellar lithium
in red part of spectra; HARPS R=115,000
LiI
1.05
HD148184
Relative intensity
HD163800
1.02
HD147933
0.99
HD147889
6707.776
6707.926
0.96
6706
6707
6708
Wavelength (A)
6709
6710
Physical situation of the interstellar gas
Very low density (1 atom per cm3 in average);
very scarce collisions – all atoms (ions) occupy
mostly the lowest energy level
Various physical parameters of different clouds
(different spectra)
Dust grains are built mostly of heavy elements
which leads to the observed depletions of these
elements in the gas phase
Possible forms of hydrogen in
interstellar clouds
Molecular hydrogen H2, HD, available to
direct observations only in far-UV
Atomic hydrogen HI, only the Lyman series
(λ<1216 Ǻ) can be observed
Ionized hydrogen HII; emission lines in
bright nebulae
Other forms like H- or H3 are less likely
present in ISM
CH radical observed towards spectroscopic binary oPer; note
the feature’s stationarity (BOES R=90,000)
2004/02/09
Relative intensity
1.08
0.99
2004/02/12
0.90
HD 23180
4280
CH
4300
Wavelength
4320
3 available to ground-based observations bands of
methylidyne (CH): 3143, 3886 i 4300 Ǻ (UVES)
C-X
Relative intensity
1.20
1.05
B-X
A-X
0.90
0.75
HD152003
CH bands
-600
-400
-200
0
Radial velocity
200
400
600
B-X (0,1) band of the CH molecule
(spectra from ESO/Paranal/UVES R=80,000)
HD169454
Relative intensity
1.08
0.99
HD147889
0.90
3627
3630
3633
Wavelength
3636
CH radical observed in the spectrum of HD148184
using UVES and Terskol/Maestro
1.00
CH
Relative intensity
0.95
0.90
0.85
UVES
0.80
0.75
23.1+/-0.2 mA
Maestro
23.3+/-0.3 mA
HD148184
0.70
4299.9
4300.0
4300.1
4300.2
Wavelength
4300.3
The well-known B-X (0,0) band of CN (Maestro)
HD203064; E(B-V)=0.30
1.4
HD 36371; E(B-V)=0.44
Relative intensity
HD 34078; E(B-V)=0.50
1.2
HD 21291; E(B-V)=0.40
HD179406; E(B-V)=0.31
1.0
0.8
3873.0
3874.5
3876.0
Wavelength
3877.5
Four observable bands of CN
*
1.5
*
Relative intensity
*
9186.94 A
*
7906.60 A
1.2
R=110,000
R=80,000
*
*
R=110,000
3579.96 A
R=80,000
0.9
*
0.6
HD169454
-150
-100
*
-50
ESO UVES
3874.60 A
0
50
Radial velocity (km/s)
100
150
200
Abundance ratio of CN/CH is evidently variable;
CFHT + Gecko R=120,000
HD 34078
HD 179406
CH
CH
CH
CN
1.0
CN
0.8
CN
Relative intensity
1.2
3876
3882
Wavelength
3888
Strongly variable abundance ratio of FeI and CN
Relative intensity
FeI
CN
1.05
HD147888
0.90
HD204827
0.75
0.60
3858
3864
Wavelength
3870
3876
Mullikan band - the strongest feature of C2 (HST high
resolution spectrum)
Relative intensity
Mullikan band of C2 observed in the HST spectrum of ζOph
1.00
0.95
0.90
2308
2312
Wavelength
2316
Phillips (1,0) band of C2 homonuclear molecule in near infrared
(UVES); different ratios – different rotational temperatures
Relative intensity
1.12
HD147889
1.05
0.98
HD169454
0.91
C2 Phillips (1,0) band
10135
10140
10145
10150
Wavelength
10155
(2-0) Phillips bands of the molecule C2 – evidently
not correlated with E(B-V) – BOES R=30,000
E(B-V)=1.05
Relative intensity
BD+58 2580
1.10 HD219287
E(B-V)=1.05
HD226868
E(B-V)=1.05
BD+59 2735
E(B-V)=1.39
HD204827
E(B-V)=1.05
1.05
1.00
0.95
C2 Phillips (2-0) band
8750
8760
8770
Wavelength
8780
The band of C3 molecule observed with the aid of 3.6m
telescope at ESO (spectrograph CES, resolution R=220,000)
Hot (T=70K) and cold (T=43K) band of C3
1.04
Relative intensity
HD147889
HARPS R=115,000
1.00
HD204827
KI
BOES R=45,000
0.96
KI
C3 band
4045
4050
Wavelength (A)
Hydroxyle (OH) features in UVES (R=80,000)
spectra of two heavily reddened stars
Relative intensity
1.1
HD147889
1.0
HD169454
0.9
OH
OH
OH
TiII
3072
3076
Wavelength
3080
Two features of the rarely observed molecule NH
Relative intensity
1.02
HD147889
HD169454
0.99
NH
0.96
NH
3354
3356
Wavelength
3358
Interstellar molecules
The observed molecular species are
composed of the most abundant elements:
H,C,O,N
Abundance ratios of the observed species
vary from cloud to cloud
The observed molecular species are far not
perfectly correlated with extinction
Doppler dance of stellar lines in the spectroscopic binary oPer;
IS NaI and diffuse bands remain stationary (BOES – R=90,000)
2004/02/12
2.0
Relative intensity
2004/02/11
2004/02/10
1.5
2004/02/09
1.0
2004/02/08
5780 5797
5850
0.5
HD 23180
5720
5760
5800
Wavelength
5840
5880
First graphical picture of diffuse interstellar bands
– DIBs (Herbig 1975)
Very different DIB profiles in:
HD210839 (red), BD +40 4220 (blue)
Relative intensity
1.04
0.96
0.88
6203
6196
0.80
6140
6160
6180
Wavelength
6200
6220
DIB spectrum is very rich – 380 features listed until
now; spectra from HARPS R=115,000;
note various strength ratios
Relative intensity
1.02
HD163800
DIB
0.99
DIB
*
*
*
0.96
*
DIB
DIB
*
DIB
HD147889
DIB
DIB
DIB
DIB
DIB
5390
5445
5500
Wavelength (A)
5555
Blue „neste” of DIBs normalized to 4964 depth;
note the identical strength ratios; HARPS
Normalized intensity
1.00
4975
4969
4980
0.98
HD163800
HD147889
0.96
4985
4964
4962
4968
4974
Wavelength (A)
4980
4986
Even very narrow DIBs remain broader than molecular
features; here in ζPer (Maestro/Terskol; R=120,000)
Relative intensity
0.96
CH 4300 A
DIB 6196
0.88
(narrowest strong)
DIB 5797
0.80
-90
-60
-30
0
30
Radial velocity (km/s)
60
90
Variable strength ratio of two major DIBs in two
targets; R=32,000 spectra from CFHT
5797
Relative intensity
1.00
0.95
ζ Oph EB-V=0.32
σ Sco EB-V=0.34
5780
0.90
5770
5780
5790
Wavelength
5800
Doppler splitting in the 6196 DIB
(ESO/Paranal/UVES)
Relative intensity
1.05
DIB 6196A
0.98
CH 4300A band
0.91
0.84
HD115363, B1Ia, E(B-V)=0.69
VLT UVES R=80,000/110,000
-120
-80
-40
0
Radial velocity
40
80
120
Diffuse interstellar bands
DIBs remain unidentified since their discovery
in 1922; it is the longest standing unsolved
problem in all of spectroscopy
One can observe many narrow and a more
limited number of broad DIBs; they are
evidently carried by different species
All conceivable forms of matter: from
hydrogen negative ion to dust grains have
been proposed as DIB carriers