J/ApJ/703/441 Yellow supergiants in M31 (Drout+, 2009)
Yellow supergiants in the Andromeda galaxy (M31).
Drout M.R., Massey P., Meynet G., Tokarz S., Caldwell N.
<Astrophys. J., 703, 441-460 (2009)>
=2009ApJ...703..441D 2009ApJ...703..441D
ADC_Keywords: Stars, supergiant ; Radial velocities ; Galaxies, photometry ;
Spectroscopy ; Surveys
Keywords: galaxies: individual (M31) - galaxies: stellar content -
stars: evolution - supergiants
Abstract:
The yellow supergiant (F- and G-type) content of nearby galaxies can
provide a critical test of stellar evolution theory, bridging the gap
between the hot, massive stars and the cool red supergiants. But, this
region of the color-magnitude diagram is dominated by foreground
contamination, requiring membership to somehow be determined.
Fortunately, the large negative systemic velocity of M31, coupled to
its high rotation rate, provides the means for separating the
contaminating foreground dwarfs from the bona fide yellow supergiants
within M31. We obtained radial velocities of ∼2900 individual targets
within the correct color-magnitude range corresponding to masses of
12M☉ and higher. A comparison of these velocities to those
expected from M31's rotation curve reveals 54 rank-1 (near certain)
and 66 rank-2 (probable) yellow supergiant members, indicating a
foreground contamination ≥96%. We expect some modest contamination
from Milky Way halo giants among the remainder, particularly for the
rank-2 candidates, and indeed follow-up spectroscopy of a small sample
eliminates four rank 2's while confirming five others.
Description:
Our observations were all carried out on eight nights during 2007
October and one night in 2007 November with the Hectospec fiber
spectrograph on the 6.5m MMT telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 87 2899 *Stars with observed radial velocities
table5.dat 73 120 Derived properties of potential M31 supergiants
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Note on table3.dat: The 127 probable M31 members (table 4 of the paper) are
stars with "Rank" 1, 2 or Cl.
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See also:
II/208 : BVRI CCD photometry in the field of M 31 (Magnier+ 1992)
J/A+A/509/A61 : Long slit spectroscopy in M31 (Saglia+, 2010)
J/ApJ/703/420 : Red supergiants in M31 (Massey et al., 2009)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- [DMM2009] Star identification (JHHMMSS.ss+DDMMSS.s;
except for "Mag-NNNNNN") (G1)
21- 22 I2 h RAh Hour of Right Ascension (J2000)
24- 25 I2 min RAm Minute of Right Ascension (J2000)
27- 32 F6.3 s RAs Second of Right Ascension (J2000)
34 A1 --- DE- Sign of the Declination (J2000)
35- 36 I2 deg DEd Degree of Declination (J2000)
38- 39 I2 arcmin DEm Arcminute of Declination (J2000)
41- 45 F5.2 arcsec DEs Arcsecond of Declination (J2000)
47- 52 F6.1 km/s Vobs Observed radial velocity
54 A1 --- f_Vobs [c] Flag on Vobs (1)
56- 59 F4.1 --- r Tonry and Davis 1979AJ.....84.1511T 1979AJ.....84.1511T r parameter
61- 66 F6.1 km/s Vexp Expected radial velocity
68- 73 F6.1 km/s Vo-Ve Observed minus expected radial velocity
75- 79 F5.2 mag Vmag V band magnitude
81- 84 F4.2 mag B-V The (B-V) color index
86- 87 A2 --- Rank Source rank (G2)
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Note (1):
c = Radial velocity observed on two different nights differed by 10km/s or
more.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- [DMM2009] Star identification (JHHMMSS.ss+DDMMSS.s;
except for Mag-253496) (G1)
21 I1 --- Rank [1/2] Source rank (G2)
23- 27 F5.2 mag VMAG Absolute V-band magnitude
28 A1 --- u_VMAG [:] Uncertainty flag on VMAG
30- 34 F5.3 [K] logT Log of effective temperature
35 A1 --- u_logT [:] Uncertainty flag on logT
37- 40 F4.2 [Lsun] log(L) Bolometric luminosity from V band magnitude
41 A1 --- u_log(L) [:] Uncertainty flag on luminosity
43- 73 A31 --- Comm Comment
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Global notes:
Note (G1): Sources are selected from the LGGS (Local Group Galaxies Survey;
Massey et al. 2006, Cat. J/AJ/131/2478) or, for "Mag-" objects, from
Magnier et al. 1992, Cat. II/208 (<[MLV92] NNNNNN> in Simbad).
Note (G2): Code of rank as follows:
1 = highly likely supergiant;
2 = probable supergiant;
3 = dwarf;
Cl = cluster.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Oct-2011