J/ApJ/750/97 The yellow and red supergiants of M33 (Drout+, 2012)
The yellow and red supergiants of M33.
Drout M.R., Massey P., Meynet G.
<Astrophys. J., 750, 97 (2012)>
=2012ApJ...750...97D 2012ApJ...750...97D
ADC_Keywords: Galaxies, optical ; Stars, giant ; Radial velocities
Keywords: galaxies: individual: M33 - galaxies: stellar content -
stars: evolution - supergiants
Abstract:
Yellow and red supergiants are evolved massive stars whose numbers and
locations on the Hertzsprung-Russell (H-R) diagram can provide a
stringent test for models of massive star evolution. Previous studies
have found large discrepancies between the relative number of yellow
supergiants (YSGs) observed as a function of mass and those predicted
by evolutionary models, while a disagreement between the predicted and
observed locations of red supergiants (RSGs) on the H-R diagram was
only recently resolved. Here, we extend these studies by examining the
YSG and RSG populations of M33. Unfortunately, identifying these stars
is difficult as this portion of the color-magnitude diagram is heavily
contaminated by foreground dwarfs. We identify the RSGs through a
combination of radial velocities and a two-color surface gravity
discriminant, and after re-characterizing the rotation curve of M33
with our newly selected RSGs, we identify the YSGs through a
combination of radial velocities and the strength of the
OIλ7774 triplet. We examine ∼1300 spectra in total and identify
121 YSGs (a sample that is unbiased in luminosity above
log(L/L☉)∼4.8) and 189 RSGs. After placing these objects on the
H-R diagram, we find that the latest generation of Geneva evolutionary
tracks shows excellent agreement with the observed locations of our
RSGs and YSGs, the observed relative number of YSGs with mass, and the
observed RSG upper mass limit.
Description:
Our samples were initially selected photometrically from the contents
of the LGGS (Local Group Galaxies Survey) of Massey et al. (2006,
Cat J/AJ/131/2478).
We obtained radial velocities for ∼1300 red and yellow stars toward
M33 using the Hectospec multi-fiber spectrograph on the 6.5m MMT
telescope. The observations were obtained over the course of two
years, with our yellow sample observed in the fall of 2009 and our red
sample (along with repeat observations for a subset of the yellow
sample) in the fall of 2010. They were obtained over three nights in
2009 October, one night in 2009 November, one night in 2009 December,
and two nights in 2010 November (NOAO proposals 2009B-0149 and
2010B-0260) with a spectral resolution of 2.8Å. The grating was
centered on 7800Å such that the wavelength coverage (6500-9000Å)
included both the CaII triplet (λλ8498, 8543, 8662) for
cross-correlation and the OIλ7774 line.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 73 408 Observed properties: red stars with radial
velocities
table3.dat 66 916 Observed properties: yellow stars with radial
velocities
table4.dat 36 135 Derived properties of probable yellow supergiants
table5.dat 36 201 Derived properties of probable red supergiants
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/ApJ/749/177 : Yellow and red supergiants in the LMC (Neugent+, 2012)
J/MNRAS/411/263 : JHK variable stars in M33 (Javadi+ 2011)
J/ApJ/703/441 : Yellow supergiants in M31 (Drout+, 2009)
J/ApJ/703/420 : Red supergiants in M31 (Massey+, 2009)
J/MNRAS/371/1405 : Variables in M33 (Hartman+, 2006)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/AJ/121/870 : BVI photometry of Variables in M33 (Macri+, 2001)
J/ApJ/501/153 : VRB photometry of red supergiants (Massey 1998)
J/ApJS/89/85 : Blue and red supergiants in M33 (Ivanov+ 1993)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LGGS Star identification (JHHMMSS.ss+DDMMSS.s)
21- 26 F6.1 km/s Vobs [-293/55] Observed radial velocity
28 A1 --- f_Vobs [d] Discrepent velocities (G1)
30- 33 F4.1 --- r [12/52] Tonry and Davis r correlation parameter
35- 40 F6.1 km/s Vexp [-255/-105] Expected radial velocity (G4)
42- 47 F6.1 km/s Vo-Ve Observed minus expected radial velocity
49- 53 F5.2 mag Vmag [15/20] V band magnitude (G2)
55- 58 F4.2 mag B-V [0.5/2.3] The (B-V) color index (G2)
60 A1 --- fB [e] e: Star is moderately crowded in the B-band
62- 65 F4.2 mag V-R [0.6/1.5] The (V-R) color index (G2)
67- 71 F5.2 mag Kmag [12/15]?=99.99 2MASS Ks band magnitude
73 I1 --- Rank [1/4] Source class rank (G3)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- LGGS Star identification (JHHMMSS.ss+DDMMSS.s)
21- 26 F6.1 km/s Vobs [-310/71] Observed radial velocity
28 A1 --- f_Vobs [d] Discrepent velocities (G1)
30- 33 F4.1 --- r [11/73] Tonry and Davis r correlation parameter
35- 40 F6.1 km/s Vexp [-264/-100] Expected radial velocity (G4)
42- 47 F6.1 km/s Vo-Ve Observed minus expected radial velocity
49- 53 F5.2 mag Vmag [12/19]?=0.64 V band magnitude (G2)(1)
55- 58 F4.2 mag B-V [0.01/1.4] The (B-V) color index (G2)
60- 63 F4.1 0.1nm EWOI [0.9/3]?=-9.9 OIλ7774 Equivalent Width
in Angstroms (Å)
65- 66 A2 --- Rank [ 1-4Cl] Source class rank (G3)
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Note (1): The "0.64" value for J013348.28+305208.8 is very dubious and left
blank in the VizieR table (but not in the FTP table); note added
by CDS.
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Byte-by-byte Description of file: table[45].dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LGGS Star identification (JHHMMSS.ss+DDMMSS.s)
21 I1 --- Rank [1/2] Source class rank (G3)
23- 27 F5.3 [K] logTeff [3/4] Logarithm of effective temperature
29- 32 F4.2 [Lsun] logLum [4/7] Logarithm of luminosity
34- 36 A3 --- Var [,1-3] Known variability reference(s) (1)
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Note (1): Variability reference as follows:
1 = Hartman et al. (2006, Cat. J/MNRAS/371/1405);
2 = Macri et al. (2001, Cat. J/AJ/121/870;
<D33 JHHMMSS.s+DDMMSS.s> in Simbad);
3 = Javadi et al. (2011, Cat. J/MNRAS/411/263).
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Global notes:
Note (G1):
d = Radial velocity observed on two different nights differed
by 10km/s or more.
Note (G2): Photometry from Massey et al., 2006, Cat. J/AJ/131/2478;
in Simbad
Note (G3): Source rank is:
1 = highly likely supergiant;
2 = possible supergiant;
3 = possible supergiant, high expected dwarf contamination;
4 = dwarf;
Cl = cluster.
Note (G4): velocity expected with Vexp = -180 - 74.3(X/R),
if X = position along the major axis and R the radial distance.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 05-Dec-2013