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 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:
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FileName Lrecl Records Explanations
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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/* . 6 Images of spectra
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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)
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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
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Bytes Format Units Label Explanations
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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
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Byte-by-byte Description of file: table35.dat
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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
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Note (1): ANN = artificial neural networks. Confusion matrix (table 4):
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Luminosity class Giants Subgiants Dwarfs
---------------------------------------------
III IV V
III 75 11 14
IV 30 19 51
V 15 4 81
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Byte-by-byte Description of file: stars.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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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)
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Acknowledgements:
S. Messina, sme(at)oact.inaf.it
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