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
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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 87 2899 *Stars with observed radial velocities table5.dat 73 120 Derived properties of potential M31 supergiants
Note on table3.dat: The 127 probable M31 members (table 4 of the paper) are stars with "Rank" 1, 2 or Cl.
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
Bytes Format Units Label Explanations
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 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)
Note (1): c = Radial velocity observed on two different nights differed by 10km/s or more.
Byte-by-byte Description of file: table5.dat
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
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.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Oct-2011
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