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J/A+A/469/713     Chromospherically active stars in CoRoT fields  (Medhi+, 2007)

Results from a spectroscopic survey in the CoRoT fields. I. Search for chromospherically active stars. Medhi B.J., Messina S., Parihar P.S., Pagano I., Muneer S., Duorah K. <Astron. Astrophys. 469, 713 (2007)> =2007A&A...469..713M
ADC_Keywords: Stars, late-type ; Stars, atmospheres ; MK spectral classification Keywords: stars: late-type - stars: activity - stars: fundamental parameters - Abstract: In this paper we report the results of the spectroscopic survey we carried out to detect chromospheric activity of late-type stars in the fields of view of the CoRoT space mission. We give an accurate MK classification of all targets, which is valuable information on both the main CoRoT project and additional science programs, by means of cross-correlation with MK standard stars, by using artificial neural networks. The presence or absence of excess Hα emission, determined using spectral subtraction technique, is used to characterize the chromospheric activity level. In most cases our MK classification agrees with the spectral classification reported in the SIMBAD database; however, there are a few stars that are found to have very different MK classes. Our survey reveals that ∼7% of late-type stars in our sample indeed possess a very active chromosphere. The measured Hα excess and the presence of the 6708Å, Li line allow us to confirm the membership of 5 targets in the young open cluster NGC 2264. Description: We present the results of our spectral classification which is made by using cross-correlation technique and the artificial neural networks (ANN). For 180 stars we give the spectral type from the literature, mostly are from SIMBAD, the spectral type and the correlation coefficient with respect to a template star that we found from cross-correlation and ANN. For stars with known parallax and 2MASS JHK magnitudes we give the absolute magnitude and dereddened B-V color along with their uncertainties and a note on X-ray emission from archival data and evolutionary stage. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table12.dat 75 180 Positions, magnitudes and spectral types table35.dat 137 180 Spectral type and correlation from Cross-corr and ANN, absolute magnitude, intrinsic B-V and notes stars.dat 114 180 *Corrected positions for the stars studied fig/* 0 6 Images of spectra
Note on stars.dat: positions of stars in declination range -1/+1deg are not reliable; this file was prepared by B. Skiff (Lowell Obs.) and added in January 2013 (see the "History" section below)
See also: B/corot : CoRoT observation log (CoRoT, 2009) J/MNRAS/298/332 : Chromospheric activity-age relation (Rocha-Pinto+ 1998) J/A+A/379/976 : Moving groups late-type stars EW + fluxes (Montes+ 2001) Byte-by-byte Description of file: table12.dat
Bytes Format Units Label Explanations
1- 2 A2 --- Sam Bright star (BS) or weak star (WS) sample 4- 6 I3 --- Seq [1/180] Serial number 8- 22 A15 --- Name Star's name 24- 33 A10 "YYYY-MM-DD" Date Observation date 36- 37 I2 h RAh Right ascension (J2000.0) 39- 40 I2 min RAm Right ascension (J2000.0) 42- 46 F5.2 s RAs Right ascension (J2000.0) 48 A1 --- DE- Declination sign (J2000.0) 49- 50 I2 deg DEd Declination (J2000.0) 52- 53 I2 arcmin DEm Declination (J2000.0) 55- 59 F5.2 arcsec DEs Declination (J2000.0) 62- 66 F5.2 mag Vmag V-band magnitude 68- 75 A8 --- SpT.S MK spectral type from SIMBAD
Byte-by-byte Description of file: table35.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq [1/180] Serial number 5- 19 A15 --- Name Star's name 21- 28 A8 --- SpType1 Spectral type from cross-correlation (CC) technique 35- 39 F5.3 --- R1 [0/1] Linear correlation coefficient related to SpType1 41- 45 A5 --- SpType2 Spectral type from ANN (1) 52- 56 F5.3 --- R2 [0/1] Linear correlation coefficient related to SpType2 58- 63 F6.3 mag VMAG ? Absolute magnitude 66- 69 F4.2 mag E_VMAG ? Error on absolute magnitude (upper limit) 72- 75 F4.2 mag e_VMAG ? Error on absolute magnitude (lower limit) 77- 80 F4.2 mag (B-V)0 ? Dereddened B-V color index 82- 85 F4.2 mag E(B-V) ? B-V color excess 87- 91 F5.3 mag e_E(B-V) ? Error on B-V color excess 93- 99 A7 --- SpType Finally assigned MK spectral type 101-137 A37 --- Notes Note on metallicity, X-ray emission and evolution stage
Note (1): ANN = artificial neural networks. Confusion matrix (table 4): -------------------------------------------- Luminosity class Giants Subgiants Dwarfs --------------------------------------------- III IV V III 75 11 14 IV 30 19 51 V 15 4 81 ---------------------------------------------
Byte-by-byte Description of file: stars.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name Star's name, as in the previous tables 17- 18 I2 h RAo.h Original right Ascension J2000 (hours) 20- 21 I2 min RAo.m Original right Ascension J2000 (minutes) 23- 27 F5.2 s RAo.s Original right Ascension J2000 (seconds) 29 A1 --- DEo.- Original declination J2000 (sign) 30- 31 I2 deg DEo.d Original declination J2000 (degrees) 33- 34 I2 arcmin DEo.m Original declination J2000 (minutes) 36- 40 F5.2 arcsec DEo.s Original declination J2000 (seconds) 43- 44 I2 h RAh Right Ascension J2000 (hours) 46- 47 I2 min RAm Right Ascension J2000 (minutes) 49- 53 F5.2 s RAs Right Ascension J2000 (seconds) 55 A1 --- DE- Declination J2000 (sign) 56- 57 I2 deg DEd Declination J2000 (degrees) 59- 60 I2 arcmin DEm Declination J2000 (minutes) 62- 65 F4.1 arcsec DEs Declination J2000 (seconds) 67 A1 --- s [TUM] Source of position: T=Tycho-2 (I/259), U=UCAC2 (I/289), M=2MASS-PSC (II/246) 69- 73 F5.2 mag Vmag V-band magnitude 75- 82 A8 --- SpType1 Spectral type from cross-correlation 84- 88 A5 --- SpType2 Spectral type from neural networks 90- 96 A7 --- SpType Final spectral type 98-114 A17 --- Com Comments concerning this entry (from B. Skiff)
Acknowledgements: S. Messina, sme(at) History: * 26-Apr-2007: Original version * 08-Jan-2013: addition of file "stars.dat", which contains corrected positions, the original ones being frequently in error for the -1/+1 zone of declination (thanks to Brian Skiff, Lowell Obs.)
(End) Patricia Vannier [CDS] 26-Apr-2007
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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