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J/ApJ/822/L5    Observed red supergiants in the inner Galaxy   (Messineo+, 2016)

Discovery of an extraordinary number of red supergiants in the inner Galaxy. Messineo M., Zhu Q., Menten K.M., Ivanov V.D., Figer D.F., Kudritzki R.-P., Rosie Chen C.-H. <Astrophys. J., 822, L5 (2016)> =2016ApJ...822L...5M (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, supergiant ; Spectra, infrared ; Equivalent widths ; Spectral types Keywords: infrared: stars - stars: evolution - supergiants Abstract: In this Letter, we present a search for Galactic red supergiant stars (RSGs) in the direction of the inner Galaxy. A total of 94 targets selected from the 2MASS (Cat. VII/233) and GLIMPSE I North (Benjamin et al. 2003, Cat. II/293; Churchwell et al. 2009PASP..121..213C) catalogs - via their blue extinction-free Q1 and Q2 colors - were spectroscopically observed at infrared wavelengths (in the H- and K-bands at R∼1000), and an extraordinary high detection rate of RSGs (>61%) was found. We identified spectroscopically 58 RSGs, based on their flat continua and large equivalent widths of the CO-band at 2.293 µm (EW>45 Å). This increase corresponds to about 25% of previously known RSGs in the Galactic region 10°<l<60°, -1.1°<b<1.1°. In order to confirm the location of the new RSGs in the inner Galaxy, distances were estimated for a subsample of 47 stars with the clump method and found to range from 3.6±0.4 to 8.6±0.7 kpc. The large new sample will allow us to investigate Galactic metallicity gradients as a function of galactocentric distances and azimuthal angles. Such information is currently an highly disputed issue to constrain models of Galaxy formation and evolution. Description: Spectroscopic observations were carried out with the Son of ISAAC (SofI; Moorwood et al. 1998Msngr..91....9M) Spectrograph on the ESO/New Technology Telescope (NTT) 3.58 m telescope of the La Silla Observatory, on the three nights from UT 2015 June 16 to 19-program ID 095.D-0252(A). Spectra with the low-resolution red grism, and the 0.6" wide slit, delivering resolution R∼980 over the wavelength range λ=1.53-2.52 µm were obtained for 94 targets. For each target a minimum number of four exposures, nodded along the slit, were taken in an ABBA sequence. Typical integration times per frame ranged from 2 to 100 s (DITsxNDITs). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 57 94 List of Observed Selected Stars
See also: VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006) II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008) J/MNRAS/427/3209 : Galactic and MC O-AGBs and RSGs stars (Jones+, 2012) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Star [1/94] Star identification number 3 A1 --- n_Star [a] Note on Star (1) 5- 6 I2 h RAh Hour of Right Ascension (J2000) 8- 9 I2 min RAm Minute of Right Ascension (J2000) 11- 15 F5.2 s RAs Second of Right Ascension (J2000) 17 A1 --- DE- Sign of the Declination (J2000) 18- 19 I2 deg DEd Degree of Declination (J2000) 21- 22 I2 arcmin DEm Arcminute of Declination (J2000) 24- 28 F5.2 arcsec DEs Arcsecond of Declination (J2000) 30- 33 F4.1 % H20 Water index percentage (H20) 35- 38 F4.1 % e_H20 Uncertainty in H20 40- 43 F4.1 0.1nm EW(CO) Equivalent width of the CO-band at 2.293µm (Å) 45- 47 F3.1 0.1nm e_EW(CO) Uncertainty in EW(CO) 49- 52 A4 --- SpType1 Spectral type derived using the relations between spectral types and EWs(CO) for red supergiants 54- 57 A4 --- SpType2 Spectral type derived using the relations between spectral types and EWs(CO) for giants
Note (1): Note as follows: a = Star 66 (2MASS J18442616-0335276) corresponds to the photometric candidate RSG A3 in Alicante 7 (Table 4 in Negueruela et al. 2011A&A...528A..59N).
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 12-Feb-2018
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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