J/AJ/104/1349 Infrared-luminous giants in M32 (Freedman, 1992)
Infrared-luminous giants in M32: an intermediate-age population?
FREEDMAN W.L.
<Astron. J. 104, 1349 (1992)>
=1992AJ....104.1349F 1992AJ....104.1349F (SIMBAD/NED Reference)
ADC_Keywords: Galaxies, optical; Stars, giant; Photometry, infrared
Abstract:
A previously unknown population of very luminous, red,
asymptotic-giant-branch stars has been identified as a result of
near-infrared (JHK) imaging in the dwarf elliptical galaxy M32.
Situated above the tip of the normal first red giant branch, these
stars are intrinsically brighter than the most luminous normal
giants in old Galactic globular clusters by approximately 2 bolometric
magnitudes. Moreover, they are a full bolometric magnitude brighter
than the brightest giants observed in our own Galactic bulge.
Several possible explanations for this population are examined,
including old long-period variables, binary mergers, supermetallicity,
and intermediate-age stars. It is suggested that the simplest
explanation at present, is that M32 had a star formation episode
less than about 5 billion years ago. These stars would then be the
evolved extended asymptotic giant branch population resulting from
that event (similar to those stars observed in the intermediate-age
clusters in the Magellanic Clouds). This population may be similar
to that in the M31 bulge, recently observed by Rich and Mould. The
detection of a young component in M32 is of particular interest
because historically, M32 has been a fiducial galaxy for population
synthesis techniques. An understanding of M32 remains crucial
for our understanding of distant and more luminous elliptical galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 37 125 M32 JK photometry
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 3 I3 --- Id Star identification number
6- 8 I3 pix Xpos X position
11- 13 I3 pix Ypos Y position
17- 21 F5.2 mag Kmag K magnitude
24- 28 F5.2 mag Jmag []? J magnitude
32- 35 F4.2 mag J-K []? J-K colour
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References: Rich R.M., Mould J.R., 1991, AJ, 101, 1286
Historical Notes: Keypunched at CDS
(End) James Marcout, Patricia Bauer [CDS] 23-Feb-1995