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J/ApJ/719/1784         Yellow supergiants in the SMC            (Neugent+, 2010)

Yellow supergiants in the Small Magellanic Cloud: putting current evolutionary theory to the test. Neugent K.F., Massey P., Skiff B., Drout M.R., Meynet G., Olsen K.A.G. <Astrophys. J., 719, 1784-1795 (2010)> =2010ApJ...719.1784N
ADC_Keywords: Magellanic Clouds ; Stars, giant ; Radial velocities ; Spectral types ; Equivalent widths ; Photometry Keywords: galaxies: individual (SMC) - galaxies: stellar content - Magellanic Clouds - stars: evolution - supergiants Abstract: The yellow supergiant content of nearby galaxies provides a critical test of massive star evolutionary theory. While these stars are the brightest in a galaxy, they are difficult to identify because a large number of foreground Milky Way stars have similar colors and magnitudes. We previously conducted a census of yellow supergiants within M31 and found that the evolutionary tracks predict a yellow supergiant duration an order of magnitude longer than we observed. Here we turn our attention to the Small Magellanic Cloud (SMC), where the metallicity is 10x lower than that of M31, which is important as metallicity strongly affects massive star evolution. The SMC's large radial velocity (∼160km/s) allows us to separate members from foreground stars. Observations of ∼500 candidates yielded 176 near-certain SMC supergiants, 16 possible SMC supergiants, along with 306 foreground stars, and provide good relative numbers of yellow supergiants down to 12M. Of the 176 near-certain SMC supergiants, the kinematics predicted by the Besancon model of the Milky Way suggest a foreground contamination of ≤4%. After placing the SMC supergiants on the Hertzsprung-Russell diagram (HRD) and comparing our results to the Geneva evolutionary tracks, we find results similar to those of the M31 study: while the locations of the stars on the HRD match the locations of evolutionary tracks well, the models overpredict the yellow supergiant lifetime by a factor of 10. Uncertainties about the mass-loss rates on the main sequence thus cannot be the primary problem with the models. Description: We initially selected stars from the USNO CCD Astrograph Catalog Part 3 (UCAC3) to have negligible proper motions (less than 15mas/yr). We used the stars' Two Micron All Sky Survey (2MASS) photometry (Skrutskie et al. 2006, Cat. VII/233) to then select a sample in the necessary color and magnitude range. Our observations were taken on the Cerro Tololo 4m telescope using Hydra, a multi-object spectrometer. All of our observations were taken over a cloudy five night span in 2009 October. In the blue, our wavelength range was 3650-4525Å with a spectral resolution of 1.3Å (3 binned pixels). In the red, our wavelength range was 7300-9050Å with a spectral resolution of 2.6Å (again 3 binned pixels). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 134 497 Properties of observed targets table2.dat 39 192 Derived properties of SMC yellow supergiants table3.dat 112 17 SMC supergiants not observed refs.dat 66 27 References
See also: I/315 : UCAC3 Catalogue (Zacharias+ 2009) VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006) II/236 : UBVR CCD survey of the Magellanic clouds (Massey+, 2002) V/13 : Probable Members of the SMC (Azzopardi+ 1975, 1979) J/ApJ/703/441 : Yellow supergiants in M31 (Drout+, 2009) J/MNRAS/353/601 : 2dF survey of the Small Magellanic Cloud (Evans+, 2004) J/AJ/126/2867 : Red supergiants in Magellanic Clouds (Massey+, 2003) J/AJ/123/855 : Magellanic Clouds Photometric Survey: the SMC (Zaritsky+, 2002) J/A+A/337/779 : V810 Cen Geneva photometry (Kienzle+ 1998) J/A+AS/30/261 : UBV and Radial Velocities of SMC Supergiants (Ardeberg+, 1977) : ASAS home page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 17 A17 --- 2MASS 2MASS identification 19 A1 --- f_2MASS [a] averaged resutlt (1) 21- 22 I2 h RAh Hour of Right Ascension (J2000) 24- 25 I2 min RAm Minute of Right Ascension (J2000) 27- 31 F5.2 s RAs Second of Right Ascension (J2000) 33 A1 --- DE- Sign of Declination (J2000) 34- 35 I2 deg DEd Degree of Declination (J2000) 37- 38 I2 arcmin DEm Arcminute of Declination (J2000) 40- 43 F4.1 arcsec DEs Arcsecond of Declination (J2000) 45- 49 F5.2 mag Ksmag 2MASS Ks band magnitude 51- 54 F4.2 mag J-Ks The (J-Ks) color index 56- 60 F5.2 mag Vmag ? V band magnitude 62- 66 F5.2 mag B-V ? The (B-V) color index 68 I1 --- r_B-V [1/5] The Vmag and B-V photometry reference (see refs.dat file) 70- 74 F5.1 km/s HRV Radial velocity 76- 80 F5.1 --- r Tondry & Davis, 1979AJ.....84.1511T, r parameter 82 I1 --- Cat [1/3] Category (G1) 84- 92 A9 --- SpT1 MK spectral classification from Hydra spectra 94-102 A9 --- SpT2 Literature MK spectral classification 104-105 I2 --- r_SpT2 [11/31]? Spectral classification reference (see refs.dat file) 107-134 A28 --- Comm Additional comments (2)
Note (1): These stars were imaged twice and their results were averaged. The average difference in Velobs was 2.2km/s and the average difference in the r parameter was 13.7. Note (2): Comments include: alternate names for the star, comments on the blue spectra and comments based on the literature search.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 17 A17 --- 2MASS 2MASS identification 19 A1 --- f_2MASS [a] No (B-V) color (1) 21 I1 --- Cat [1/2] Category (G1) 23- 27 F5.3 10+3K Teff Effective temperature 29- 33 F5.3 [Lsun] logL Log luminosity 35 A1 --- l_EW Limit flag on EW 36- 39 F4.1 0.1nm EW Equivalent width of OI 7774Å line (2)
Note (1): This star didn't have a known B-V color, so instead we used the star's J-K color to derive the Teff and logL. Note (2): We found we couldn't measure OI (7774Å) if it had an equivalent width of less than 0.2Å. The units are in Angstroms.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 17 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs) 19 A1 --- f_2MASS [a] stars we selected but were not observed 21- 22 I2 h RAh Hour of right ascension (J2000) 24- 25 I2 min RAm Minute of right ascension (J2000) 27- 31 F5.2 s RAs Second of right ascension (J2000) 33 A1 --- DE- Sign of declination (J2000) 34- 35 I2 deg DEd Degree of declination (J2000) 37- 38 I2 arcmin DEm Arcminute of declination (J2000) 40- 43 F4.1 arcsec DEs Arcsecond of declination (J2000) 45- 49 F5.2 mag Ksmag 2MASS Ks-band magnitude 51- 54 F4.2 mag J-K J-K color index 56- 60 F5.2 mag Vmag V-band magnitude 62 I1 --- r_Vmag [1-3] Reference for Vmag (see refs.dat file) 64- 68 A5 --- SpT MK spectral type from litterature 70- 71 I2 --- r_SpT [18/32] Reference for spectral classification (see refs.dat file) 73- 87 A15 --- AName Alternative name(s) 89-112 A24 --- Comm Comment
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Ref [1/32] Reference code 4- 22 A19 --- BibCode Bibcode 24- 42 A19 --- Aut Author's name(s) 44- 66 A23 --- Comm Comment
Global notes: Note (G1): Category as follows: 1 = SMC supergiant; 2 = possible SMC supergiant; 3 = foreground dwarf.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 20-Jun-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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