J/MNRAS/525/3693 HST medium-band imaging of M32 (Jones+, 2023)
Hubble Space Telescope imaging of the compact elliptical galaxy M32 reveals a
dearth of carbon stars.
Jones O.C., Boyer M.L., McDonald I., Meixner M., van Loon J.T.
<Mon. Not. R. Astron. Soc. 525, 3693-3701 (2023)>
=2023MNRAS.525.3693J 2023MNRAS.525.3693J (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, carbon ; Photometry, infrared ;
Photometry, HST
Keywords: stars: late-type - stars: variables: Cepheids -
galaxies: individual: (M32) - galaxies: stellar content -
infrared: galaxies - infrared: stars
Abstract:
We present new Hubble Space Telescope Wide-Field Camera 3/infrared
medium-band photometry of the compact elliptical galaxy M32,
chemically resolving its thermally pulsating asymptotic giant branch
stars. We find 2829 M-type stars and 57 C stars. The carbon stars are
likely contaminants from M31. If carbon stars are present in M32 they
are so in very low numbers. The uncorrected C/M ratio is
0.020±0.003; this drops to less than 0.007 after taking into account
contamination from M31. As the mean metallicity of M32 is just below
solar, this low ratio of C to M stars is unlikely due to a metallicity
ceiling for the formation of carbon stars. Instead, the age of the
asymptotic giant branch (AGB) population is likely to be the primary
factor. The ratio of AGB to red giant branch stars in M32 is similar
to that of the inner disc of M31 which contain stars that formed
1.5-4Gyr ago. If the M32 population is at the older end of this age
then its lack of C-stars may be consistent with a narrow mass range
for carbon star formation predicted by some stellar evolution models.
Applying our chemical classifications to the dusty variable stars
identified with Spitzer, we find that the x-AGB candidates identified
with Spitzer are predominately M-type stars. This substantially
increases the lower limit to the cumulative dust-production rate in
M32 to >1.20x10-5M☉/yr.
Description:
We target four fields in M32, with HST's WFC3/IR medium-band F127M,
F139M, and F153M filters in Cycle 27 (GO-15952, PI: Jones).
M32 WFC3 point-source catalogue.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 65 115295 Master catalogue (table 2)
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See also:
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID [1/170106] Unique identification number
8- 15 F8.5 deg RAdeg Right Ascension (J2000)
17- 24 F8.5 deg DEdeg Declination (J2000)
26- 31 F6.3 mag F127M HST F127M magnitude
33- 37 F5.3 mag e_F127M HST F127M magnitude 1σ error
39- 44 F6.3 mag F139M HST F139M magnitude
46- 50 F5.3 mag e_F139M HST F139M magnitude 1σ error
52- 57 F6.3 mag F153M HST F153M magnitude
59- 63 F5.3 mag e_F153M HST F153M magnitude 1σ error
65 A1 --- Type [CM] AGB classification: C or M
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Acknowledgements:
Olivia Jones, olivia.jones(at)stfc.ac.uk
(End) Patricia Vannier [CDS] 22-Feb-2024