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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
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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: table[246].dat
Bytes Format Units Label Explanations
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
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 22-May-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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