J/MNRAS/446/1584 IRAC point sources for M32 (Jones+, 2015)
A Spitzer Space Telescope survey of extreme asymptotic giant branch stars
in M32.
Jones O.C., McDonald I., Rich R.M., Kemper F., Boyer M.L., Zijlstra A.A.,
Bendo G.J.
<Mon. Not. R. Astron. Soc., 446, 1584-1596 (2015)>
=2015MNRAS.446.1584J 2015MNRAS.446.1584J (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, late-type ; Photometry, infrared
Keywords: stars: AGB and post-AGB - stars: late-type - stars: mass-loss -
galaxies: individual: M32 - galaxies: stellar content -
infrared: stars
Abstract:
We investigate the population of cool, evolved stars in the Local
Group dwarf elliptical galaxy M32, using Infrared Array Camera
observations from the Spitzer Space Telescope. We construct deep
mid-infrared colour-magnitude diagrams for the resolved stellar
populations within 3.5 arcmin of M32's centre, and identify those
stars that exhibit infrared excess. Our data are dominated by a
population of luminous, dust-producing stars on the asymptotic giant
branch (AGB) and extend to approximately 3 mag below the AGB tip. We
detect for the first time a sizeable population of `extreme' AGB
stars, highly enshrouded by circumstellar dust and likely completely
obscured at optical wavelengths. The total dust-injection rate from
the extreme AGB candidates is measured to be 7.5x10-7M☉/yr,
corresponding to a gas mass-loss rate of 1.5x10-4M☉/yr. These
extreme stars may be indicative of an extended star formation epoch
between 0.2 and 5Gyr ago.
Description:
Spitzer observations of M32 (Programme Identification [PID] 3400, PI.
M. Rich) were obtained on 2005 January 18 UT with IRAC at 3.6, 4.5,
5.8, and 8um. For each IRAC channel, 4 (5.2-arcminx5.2arcmin) frames
at 23 dither positions were taken in a cycling pattern with 30-s
exposures to build redundancy against outliers and artefacts,
resulting in total integration time on M32 of 2760s over most of the
map. Observations were centred at RA=00:42:41.6, DE=+40:55:53.6
(J2000.0) and cover an area of approximately 6-arcminx7-arcmin in
all four IRAC channels around the centre of M32, plus an off-field
region (offset by one pointing) of the same size to the north-west for
IRAC bands 2 and 4 or south-east for IRAC bands 1 and 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 1522 Catalogue of point sources for M32
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See also:
J/AJ/104/1349 : Infrared-luminous giants in M32 (Freedman, 1992)
J/ApJ/504/113 : F175W and F275W photometry of M31 and M32 (Brown+, 1998)
J/ApJ/532/308 : Hot Horizontal Branch Stars in the Core of M32 (Brown+ 2000)
J/ApJ/708/817 : RR Lyrae variables in M32 and M31 (Fiorentino+, 2010)
J/ApJ/725/670 : Kinematics in the M32 nucleus (Seth, 2010)
J/MNRAS/425/1459 : RR Lyrae in M32 (Sarajedini+, 2012)
J/A+A/539/A138 : RR Lyr variable stars in M32 (Fiorentino+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- SSTM32 [1/1522] Sequential number
6- 25 A20 --- Name Source name (JHHMMSS.ss+DDMMSS.ss)
27- 33 F7.4 deg RAdeg Right ascension (J2000)
35- 41 F7.4 deg DEdeg Declination (J2000)
43- 48 F6.3 mag [3.6] ? IRAC 3.6um magnitude
50- 54 F5.3 mag e_[3.6] ? rms uncertainty on [3.6]
56- 61 F6.3 mag [4.5] ? IRAC 4.5um magnitude
63- 67 F5.3 mag e_[4.5] ? rms uncertainty on [4.5]
69- 74 F6.3 mag [5.8] ? IRAC 5.8um magnitude
76- 80 F5.3 mag e_[5.8] ? rms uncertainty on [5.8]
82- 87 F6.3 mag [8.0] ? IRAC 8.0um magnitude
89- 93 F5.3 mag e_[8.0] ? rms uncertainty on [8.0]
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Jun-2015