J/ApJ/699/150 Spectral classifications of Massive YSOs in LMC (Seale+, 2009)
The evolution of massive young stellar objects in the Large Magellanic Cloud.
I. Identification and spectral classification.
Seale J.P., Looney L.W., Chu Y.-H., Gruendl R.A., Brandl B.,
Rosie Chen C.-H., Brandner W., Blake G.A.
<Astrophys. J., 699, 150-167 (2009)>
=2009ApJ...699..150S 2009ApJ...699..150S
ADC_Keywords: Magellanic Clouds ; YSOs ; Spectral types
Keywords: galaxies: individual (LMC) - infrared: stars -
instrumentation: spectrographs - Magellanic Clouds -
stars: evolution - stars: formation
Abstract:
We present and categorize Spitzer infrared spectrometer spectra of 294
objects in the Large Magellanic Cloud (LMC) to create the largest and
most complete catalog of massive young stellar object (YSO) spectra in
the LMC. Target sources were identified from infrared photometry and
multiwavelength images indicative of young, massive stars highly
enshrouded in their natal gas and dust clouds. Several objects have
been spectroscopically identified as non-YSOs and have features
similar to more-evolved stars such as red supergiants, asymptotic
giant branch (AGB), and post-AGB stars. Our sample primarily consists
of 277 objects we identify as having spectral features indicative of
embedded YSOs. The remaining sources are comprised of seven C-rich
evolved sources, eight sources dominated by broad silicate emission,
and one source with multiple broad emission features.
Description:
The IRS on board Spitzer is composed of four modules, two of which
provide low spectral resolution (R∼60-127) between 5.2 and 37.9um,
and two provide high spectral resolution (R∼600) between 9.9 and
36.8um. To cover the entire ∼5 to 37um wavelength range, we used
the IRS modules SL (short wavelength, low-resolution), SH (short
wavelength, high-resolution), and LH (long wavelength,
high-resolution).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 133 294 Source classification
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See also:
J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 44 A44 --- Type Source classification, this paper
46- 63 A18 --- [GC2009] Object identification (HHMMSS.ss+DDMMSS.s)
65- 69 A5 --- KSPW Kraemer et al. (2002ApJS..140..389K 2002ApJS..140..389K) class (5)
71- 72 A2 --- GC09 Gruendl & Chu (2009, J/ApJS/184/172) class (1)
74- 76 A3 --- Sil [yes no] Presence of Silicate absorption?
78- 83 F6.3 --- c.Sil ? contribution of Silicate (2)
85- 87 A3 --- PAH1 [yes no] Presence of PAH 5-10um emission?
89- 94 F6.3 --- c.PAH1 ? Contribution of PAH1 (2)
96- 98 A3 --- PAH2 [yes no] Presence of PAH 10-13um emission?
100-105 F6.3 --- c.PAH2 ? Contribution of PAH2 (2)
107-109 A3 --- fse [yes no] Presence of Fine-Structure line
emission?
111-116 F6.3 --- c.fse ? Contribution of fse (2)
118 A1 --- mul [X] Possible multiple? (3)
120 A1 --- Mol [X] Molecular cloud environment? (3)
122 A1 --- HaC [X] Compact Hα environment? (3)
124 A1 --- HaD [X] Diffuse Hα environment? (3)
126-131 F6.2 --- SII ? [SII] concentration ratio (4)
133 A1 --- Dust [X] Diffuse dust environment (3)
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Note (1): Primary Gruendl & Chu (2009, J/ApJS/184/172, GC09)
classifications for the entire source sample. When applicable, the
primary classification is followed by the secondary classification.
GC09 classifications are as follows:
C = candidate YSO
A = AGB or post-AGB star (non-ERO)
D = diffuse source
G = background galaxy
S = normal star
E = extremely red object
U = unknown. Source without a GC09 classification.
Note (2): Dot-product of the source's spectrum with the eigenvector
containing the pertaining spectral feature.
Note (3): 'X' indicates source(s) in the environment
Note (4): Ratio of the equivalent width per pixel of the [SIII] 18.7um
fine-structure line of the full slit extraction to the equivalent
width per pixel of the same line taken at the 1-pixel wide
"off-source" slit position. Sources without values do not have a
measureable [SIII] line.
Note (5): the classification is made of 2 levels:
* Level 1 is a number depending on the temperature of the dominant
emitter, as follows:
1 = naked stars (no apparent circumstellar emission)
2 = stars with dust (typically ed supergiants or AGB stars)
3 = warm, dusty objects
4 = cool, dusty objects
5 = very red objects (typically star-forming regions or PNe)
6 = continuum-free objects but with emission lines (e.g. SNR or novae)
7 = flux-free and/or fatally flawed spectra
* Level 2 specifies spectral features superimposed on the overall SED:
SE = Silicate (or O-rich) dust emission (10-12 and 18-20um)
SB = Silicate emission in self-absorption (10um)
SA = Silicate absorption (10-12um)
SC = Silicate emission from crystalline grains (33, 40, 43um)
SEC = Silicate emission from crystalline grains (11, 19, 23, 33um)
CE = C-rich dust emission, primarily from SiC (11.5um)
CR = C-rich dust emission in a reddened shell
(with features at 11.5 and 26um, often 13.7um absorption)
CT = 8, 11.5, 21, 26um, no 13.7um absorption
CN = C-rich nebulae
C/SE = C-rich, plus silicate emission (10-12um)
C/SC = C-rich, plus crystalline silicate emission
U/SC = Crystalline silicate and UIR emission features
U = Prominent UIR emission features (3.3, 6.2, 7.7-7.9, 8.6,
and 11.2um, most likely due to PAH (polycyclic aromatic
hydrocarbons)
PN = Many prominent atomic fine-structure lines typical of PNe
PU = As PN, but with strong UIR emission
W = Emission peaks 6-8um
F = Basically featureless
E = Strong emission lines
M = Miscellaneous
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 30-Apr-2010