J/ApJ/715/1094 Census of self-obscured massive stars (Khan+, 2010)
Census of self-obscured massive stars in nearby galaxies with Spitzer:
implications for understanding the progenitors of SN 2008S-like transients.
Khan R., Stanek K.Z., Prieto J.L., Kochanek C.S., Thompson T.A.,
Beacom J.F.
<Astrophys. J., 715, 1094-1108 (2010)>
=2010ApJ...715.1094K 2010ApJ...715.1094K
ADC_Keywords: Galaxies, nearby ; Photometry, infrared ; Stars, giant
Keywords: catalogs - galaxies: individual (M33, NGC 300, M81, NGC 6946) -
supernovae: general - supernovae: individual (SN 2008S)
Abstract:
A new link in the causal mapping between massive stars and potentially
fatal explosive transients opened with the 2008 discovery of the
dust-obscured progenitors of the luminous outbursts in NGC 6946 and
NGC 300. Here, we carry out a systematic mid-IR photometric search for
massive, luminous, and self-obscured stars in four nearby galaxies:
M33, NGC 300, M81, and NGC 6946. For detection, we use only the 3.6um
and 4.5um IRAC bands, as these can still be used for multi-epoch
Spitzer surveys of nearby galaxies (≲10Mpc). We combine familiar
point-spread function and aperture photometry with an innovative
application of image subtraction to catalog the self-obscured massive
stars in these galaxies. In particular, we verify that stars analogous
to the progenitors of the NGC 6946 (SN 2008S) and NGC 300 transients
are truly rare in all four galaxies: their number may be as low as ∼1
per galaxy at any given moment. This result empirically supports the
idea that the dust-enshrouded phase is a very short lived phenomenon
in the lives of many massive stars and that these objects constitute a
natural extension of the asymptotic giant branch sequence. We also
provide mid-IR catalogs of sources in NGC 300, M81, and NGC 6946.
Description:
Section 2 of the paper describes the methodology of our search for
self-obscured massive stars in archival Spitzer IRAC data. We use the
same criteria of [3.6]-[4.5]>1.5mag and M4.5←10mag used by Thompson
et al. (2009, Cat. J/ApJ/705/1364) to select extremely red and bright
objects (extreme asymptotic giant branch (EAGB) objects) similar to
the SN 2008S and NGC 300-2008OT progenitors.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 20 Photometry for the EAGBs in M33
table2.dat 47 11241 MIR catalog for 11241 point sources in NGC 300
table3.dat 58 10 Photometry for the EAGBs in NGC 300
table4.dat 47 6021 MIR catalog for 6021 point sources in M81
table5.dat 58 39 Photometry for the EAGBs in M81
table6.dat 47 5601 MIR catalog for 5601 point sources in NGC 6946
table7.dat 58 30 Photometry for the EAGBs in NGC 6946
table8.dat 58 10 Photometry for the EAGBs in LMC and SMC
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See also:
II/305 : SAGE LMC and SMC IRAC Source Catalog (IPAC 2009)
J/ApJ/705/1364 : MIR catalog of point sources in M33 (Thompson+, 2009)
J/ApJ/697/1993 : Spitzer study of AGB stars. III. (Boyer+, 2009)
J/AJ/138/1003 : IR photometry of massive LMC stars (Bonanos+, 2009)
J/A+A/476/1161 : Spitzer photometry of M33 (Verley+, 2007)
J/ApJ/655/212 : S3MC IRAC and MIPS photometry (Bolatto+, 2007)
J/ApJ/648/987 : UV through far-IR analysis of M81 (Perez-Gonzalez+, 2006)
Byte-by-byte Description of file: table[13578].dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Gal Galaxy name
7- 16 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
18- 27 F10.6 deg DEdeg Declination in decimal degrees (J2000)
29 A1 --- l_[3.6] Limit flag on [3.6]
30- 34 F5.2 mag [3.6] Spitzer/IRAC 3.6um magnitude
36- 40 F5.2 mag [4.5] Spitzer/IRAC 4.5um magnitude
42 A1 --- l_Color Limit flag on Color
43- 46 F4.2 mag Color Spitzer/IRAC [3.6]-[4.5] color index
48- 52 F5.2 mag [5.8] ? Spitzer/IRAC 5.8um magnitude
54- 58 F5.2 mag [8.0] ? Spitzer/IRAC 8.0um magnitude
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Byte-by-byte Description of file: table[246].dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
11- 19 F9.5 deg DEdeg Declination in decimal degrees (J2000)
21- 25 F5.2 mag [3.6] Spitzer/IRAC 3.6 micron band magnitude
27- 30 F4.2 mag e_[3.6] The 1σ uncertainty in [3.6]
32- 36 F5.2 mag [4.5] Spitzer/IRAC 4.5 micron band magnitude
38- 41 F4.2 mag e_[4.5] The 1σ uncertainty in [4.5]
43- 47 F5.2 mag Color Spitzer/IRAC [3.6]-[4.5] color index
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 22-May-2012