J/MNRAS/381/1219 High mass-loss AGB stars in the Galactic Bulge (Ojha+, 2007)
High mass-loss asymptotic giant branch stars detected by the
Midcourse Space Experiment in the "intermediate" and "outer" Galactic bulge.
Ojha D.K., Tej A., Schultheis M., Omont A., Schuller F.
<Mon. Not. R. Astron. Soc. 381, 1219 (2007)>
=2007MNRAS.381.1219O 2007MNRAS.381.1219O
ADC_Keywords: Infrared sources ; Photometry, infrared
Keywords: stars: AGB and post-AGB - circumstellar matter - stars: mass-loss -
dust, extinction - infrared: stars
Abstract:
We present a study of MSX point sources in the Galactic bulge
(|l|<3deg, 1deg<|b|<5deg), observed in the A, C, D and E bands
(8-21um), with a total area 48 square degrees and more than 7000
detected sources in the MSX D band (15 micron). We discuss the nature
of the MSX sources [mostly asymptotic giant branch (AGB) stars], their
luminosities, the interstellar extinction, the mass-loss rate
distribution and the total mass-loss rate in the bulge. The
mid-infrared data of MSX point sources have been combined with the
near-infrared (J, H and Ks) data of Two Micron All Sky Survey. The
cross-identification was restricted to Ks-band detected sources with
Ks≤11mag. However, for those bright MSX D-band sources ([D]<4.0mag),
which do not satisfy this criterion, we have set no Ks-band magnitude
cut-off. The bolometric magnitudes and the corresponding luminosities
of the MSX sources were derived by fitting blackbody curves. The
relation between dM/dt and (Ks-[15])0 was used to derive the mass-loss
rate of each MSX source in the bulge fields. Except for very few
post-AGB stars, planetary nebulae and OH/IR stars, a large fraction of
the detected sources at 15 micron (MSX D band) are AGB stars well
above the red giant branch tip. A number of them show an excess in
([A]-[D])0 and (Ks-[D])0 colours, characteristic of mass-loss. These
colours, especially (Ks-[D])0, enable estimation of the mass-loss
rates (dM/dt) of the sources in the bulge fields which range from
10-7 to 10-4M☉/yr. Taking into consideration the
completeness of the mass-loss rate bins, we find that the contribution
to the integrated mass-loss is probably dominated by mass-loss rates
larger than 3x10-7M☉/yr and is about
1.96x10-4M☉/yr/deg2 in the `intermediate' and `outer' bulge
fields of sources with mass-loss rates, dM/dt>3x10-7M☉/yr. The
corresponding integrated mass-loss rate per unit stellar mass is
0.48x10-11/yr. Apart from this, the various mid- and near-infrared
colour-colour and colour-magnitude diagrams are discussed in the paper
to study the nature of the stellar population in the MSX bulge fields.
Description:
We report the study of the MSX point sources in the 'intermediate' and
'outer' Galactic bulge fields (|l|<3deg, 1deg<|b|<5deg) with
a total area ∼48deg2 and more than 7000 detected sources in the MSX
D-band (15 micron). We have combined the mid-infrared data of the MSX
point sources with the near-infrared 2MASS data to determine their
nature, luminosities, the interstellar extinction, the mass-loss rate
distribution and the total mass-loss rate in the bulge.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 60 The detailed characteristics of the MSX bulge
subfields
table2.dat 146 2314 Catalogue of MSX-2MASS sources in the bulge fields
with their DENIS & ISOGAL counterparts.
table3.dat 146 1457 Sub-sample of MSX-2MASS sources from table2.dat
with AV, mass-loss rate & luminosity values
fig4_1.fit 2880 666 Color-magnitude diagrams (J-Ks/Ks) of 2MASS sources
in the bulge fields, part 1
fig4_2.fit 2880 666 Color-magnitude diagrams (J-Ks/Ks) of 2MASS sources
in the bulge fields, part 2
fig4_3.fit 2880 666 Color-magnitude diagrams (J-Ks/Ks) of 2MASS sources
in the bulge fields, part 3
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See also:
V/114 : MSX6C Infrared Point Source Catalog (Egan+ 2003)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/243 : The ISOGAL Point Source Catalogue - IGPSC (Omont+ 2003)
B/denis : The DENIS database (DENIS Consortium, 2005)
J/AJ/122/1844 : MSX and 2MASS cross-correlation in LMC (Egan+, 2001)
J/A+A/405/531 : IR spec. of ISOGAL Galactic Bulge sources (Schultheis+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- Field MSX bulge subfields
31- 33 I3 deg2 Dens1 MSX source density at D-band (per square deg)
36- 39 F4.2 mag AV Mean interstellar extinction
42- 45 F4.2 mag e_AV Sigma in interstellar extinction
48- 50 I3 --- N2MASS Number of 2MASS sources (Ks≤11.0mag)
53- 55 I3 --- NFrgd Number of "Foreground" sources
58- 59 I2 --- NB Number of "B" sources
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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2- 6 I5 --- Seq Source number
8- 13 A6 --- --- [MSX6C-]
14- 30 A17 --- MSX MSX6C designation (GLLL.llll-bb.bbbb)
33- 40 F8.4 deg RAdeg Right ascension in decimal degrees (J2000)
43- 50 F8.4 deg DEdeg Declination in decimal degrees (J2000)
54- 60 F7.4 deg GLON [-3/3] Galactic longitude
64- 70 F7.4 deg GLAT Galactic latitude
73- 77 F5.2 mag Jmag ?=99.99 2MASS J magnitude (G1)
80- 84 F5.2 mag Hmag ?=99.99 2MASS H magnitude (G1)
87- 91 F5.2 mag Kmag ?=99.99 2MASS Ks magnitude (G1)
94- 98 F5.2 mag Kmag2 ?=99.99 DENIS Ks magnitude (G1)
101-105 F5.2 mag Amag ?=99.99 MSX A band (8.3um) magnitude (G1)
108-112 F5.2 mag Cmag ?=99.99 MSX C band (12.1um) magnitude (G1)
115-119 F5.2 mag Dmag ?=99.99 MSX D band (14.7um) magnitude (G1)
122-126 F5.2 mag Emag ?=99.99 MSX E band (21.3um) magnitude (G1)
129-133 F5.2 mag [7]mag ?=99.99 ISOGAL magnitude at 7 micron (G1)
136-140 F5.2 mag [15]mag ?=99.99 ISOGAL magnitude at 15 micron (G1)
142-146 F5.2 mag AV Interstellar extinction
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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2- 7 A6 --- --- [MSX6C-]
8- 24 A17 --- MSX MSX6C designation (GLLL.llll-bb.bbbb)
27- 36 A10 --- IRAS IRAS Name
38- 41 F4.1 deg GLON [-3/3] Galactic longitude
43- 46 F4.1 deg GLAT Galactic latitude
49- 53 F5.2 mag Jmag ?=99.99 2MASS J magnitude (G1)
56- 60 F5.2 mag Hmag ?=99.99 2MASS H magnitude (G1)
63- 67 F5.2 mag Kmag 2MASS Ks magnitude
70- 74 F5.2 mag Amag MSX A band magnitude
77- 81 F5.2 mag Dmag MSX D band magnitude
84- 88 F5.2 mag [7]mag ?=99.99 ISOGAL magnitude at 7 micron (G1)
91- 95 F5.2 mag [15]mag ?=99.99 ISOGAL magnitude at 15 micron (G1)
96-101 F6.1 Jy FC ?=- MSX C band flux (1)
102-107 F6.1 Jy FE ?=- MSX E band flux (1)
109-113 F5.1 Jy F12um ?=- IRAS flux at 12 micron (1)
115-119 F5.1 Jy F25um ?=- IRAS flux at 25 micron (1)
122-125 F4.1 mag AV Interstellar extinction (in mag)
129-136 E8.3 [solLum] Lum ?=- Luminosity
140-146 E7.2 solMass/yr dM/dt Mass-loss rate
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Note (1): Magnitude assigned a value of "-" implies that the source is
not detected in the corresponding band.
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Global notes:
Note (G1): Magnitude assigned a value of 99.99 implies that the source is
not detected in the corresponding band.
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Acknowledgements:
Devendra Ojha, ojha(at)tifr.res.in
(End) Patricia Vannier [CDS] 03-Sep-2007