J/ApJ/835/61 Chromospherically active stars in RAVE. II. (Zerjal+, 2017)
Chromospherically active stars in the RAVE survey.
II. Young dwarfs in the solar neighborhood.
Zerjal M., Zwitter T., Matijevic G., Grebel E.K., Kordopatis G., Munari U.,
Seabroke G., Steinmetz M., Wojno J., Bienayme O., Bland-Hawthorn J.,
Conrad C., Freeman K.C., Gibson B.K., Gilmore G., Kunder A., Navarro J.,
Parker Q.A., Reid W., Siviero A., Watson F.G., Wyse R.F.G.
<Astrophys. J., 835, 61-61 (2017)>
=2017ApJ...835...61Z 2017ApJ...835...61Z (SIMBAD/NED BibCode)
ADC_Keywords: Stars, ages; Stars, dwarfs; Stars, emission; Stars, nearby ;
Equivalent widths ; Spectral types
Keywords: catalogs; stars: activity; stars: chromospheres;
stars: emission-line, Be; stars: evolution; stars: pre-main sequence
Abstract:
A large sample of over 38000 chromospherically active candidate
solar-like stars and cooler dwarfs from the RAVE survey is addressed
in this paper. An improved activity identification with respect to the
previous study was introduced to build a catalog of field stars in the
solar neighborhood with an excess emission flux in the calcium
infrared triplet wavelength region.
The central result of this work is the calibration of the age-activity
relation for main-sequence dwarfs in a range from a few 10Myr up to a
few Gyr. It enabled an order of magnitude age estimation of the entire
active sample. Almost 15000 stars are shown to be younger than 1Gyr
and ∼2000 younger than 100Myr. The young age of the most active stars
is confirmed by their position off the main sequence in the J-K versus
NUV-V diagram showing strong ultraviolet excess, mid-infrared excess
in the J-K versus W1-W2 diagram, and very cool temperatures
(J-K>0.7). They overlap with the reference pre-main-sequence RAVE
stars often displaying X-ray emission. The activity level increasing
with the color reveals their different nature from the solar-like
stars and probably represents an underlying dynamo-generating magnetic
fields in cool stars.
Of the RAVE objects from DR5, 50% are found in the TGAS catalog and
supplemented with accurate parallaxes and proper motions by Gaia. This
makes the database of a large number of young stars in a combination
with RAVE's radial velocities directly useful as a tracer of the very
recent large-scale star formation history in the solar neighborhood.
Description:
This work reports on the improved identification of stellar activity
in the catalog introduced by Zerjal+ 2013ApJ...776..127Z 2013ApJ...776..127Z (Paper I) and
extends its quality control. Over 9000 unreliable or improper spectra
were removed from the sample (see Section 2). Two thousand nine
hundred nineteen new spectra of 2882 stars published for the first
time in RAVE DR5 (see III/279) were found to show signs of activity
and were added to the active catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 47 34791 *List of young active RAVE dwarfs with CaII
infrared triplet (CaII IRT; 8498, 8542 and
8662Å) emission levels and ages
table6.dat 139 137 Table of 137 stars with known ages from
the literature
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Note on table4.dat: this table lists equivalent widths of excessive emission
(EWirt) in Ca II infrared triplet lines for 34791 emission-type spectra from
the RAVE Survey (DR5, Kunder+ 2017, Cat. III/279).
EWirt is a sum of excessive equivalent widths in all three lines of the
triplet. For details in EWirt estimation see Zerjal+ 2013ApJ...776..127Z 2013ApJ...776..127Z
Stellar ages are estimated from an empirical activity-age relation
using EWirt from this table and Eq. 2.
For discussion on uncertainties of derived ages see the paper.
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See also:
B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2015)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
III/279 : RAVE 5th data release (Kunder+, 2017)
J/AJ/111/439 : Chromospheric emission in late-type stars. (Henry+ 1996)
J/MNRAS/298/332 : Chromospheric activity-age relation (Rocha-Pinto+ 1998)
J/A+A/348/897 : Ages of main-sequence stars (Lachaume+, 1999)
J/ApJS/152/261 : Chromospheric Ca II emission in nearby stars (Wright+, 2004)
J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004)
J/AJ/132/161 : NStars project: The southern sample. I. (Gray+, 2006)
J/ApJ/658/480 : Pre-main-sequence stars in Lupus association (Makarov+, 2007)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/ApJ/734/70 : Chromospheric activity of Southern stars (Arriagada, 2011)
J/MNRAS/411/2770 : Hot white dwarfs in GALEX-DR5 (Bianchi+, 2011)
J/A+A/558/A53 : MW global survey of star clusters. II. (Kharchenko+, 2013)
J/A+A/552/A27 : Stellar activity and kinematics of FGK stars (Murgas+, 2013)
J/A+A/551/L8 : Chromospheric activity of field stars (Pace, 2013)
J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)
J/A+A/562/A54 : Galactic open clusters in RAVE (Conrad+, 2014)
J/ApJ/823/59 : WISE and 2MASS photometry of M giant stars (Li+, 2016)
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg Right ascension (J2000)
13- 22 F10.6 deg DEdeg Declination (J2000)
24- 27 I4 --- SNR [21/2031] Signal-to-noise ratio of spectrum
30- 34 F5.2 0.1nm EWirt [-1.1/4] Equivalent width of CaII IRT
excess emission
37- 40 F4.2 0.1nm e_EWirt [0.01/0.5] EWirt uncertainty
43- 47 F5.2 --- LogAge [7/12.2] Log10 of stellar age (1)
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Note (1): Age is estimated from the activity-age relation (Eq. 2):
logτ=0.49Å-2EW2IRT-2.15Å-1EWIRT+9.44
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right ascension (J2000)
11- 19 F9.5 deg DEdeg Declination (J2000)
21- 23 I3 --- SNR [20/238] Signal to noise ratio per pixel
25- 29 F5.2 0.1nm EWirt [-0.2/3.3] Equivalent width of CaII IRT excess
emission
31- 37 F7.1 Myr Age1 First value of age
38 A1 --- --- [,]
39- 42 I4 Myr Age2 ? Second value of age
44- 46 A3 --- r_Age1 Reference(s) for Age1 (and Age2) (1)
48- 61 A14 --- Group Group
63- 65 A3 --- r_Group Reference(s) for cluster or
moving group membership (1)
67- 71 F5.2 --- logR'HK1 ? logR'HK (2)
72 A1 --- --- [,]
74- 78 F5.2 --- logR'HK2 ? Second value of logR'HK (2)
80- 82 F3.1 mag NUV-V [4.7/8.4]? NUV-V color index
84- 87 F4.2 mag B-V [0.1/1.6]? B-V color index
89- 92 F4.2 mag J-K [0.2/1.1] 2MASS J-K color index
94- 99 F6.3 mag W1-W2 [-0.2/0.5]? WISE W1-W2 color index
101-106 A6 --- SpT MK spectral type
108-139 A32 --- Type SIMBAD object type(s)
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Note (1): The references are marked as follows:
A = Arriagada 2011, J/ApJ/734/70
C = Conrad et al. 2014, J/A+A/562/A54
D = Dias et al. 2012, B/ocl
I = Isaacson & Fischer 2010, J/ApJ/725/875
K = Kharchenko et al. 2013, J/A+A/558/A53
M = Makarov 2007, J/ApJ/658/480
T = Torres et al. 2008hsf2.book..757T 2008hsf2.book..757T
W = Wright et al. 2004, J/ApJS/152/261
Note (2): R'HK is a ratio between the sum of emission fluxes in the CaII H&K
lines (bandwidth of 1Å) and the bolometric flux of the star.
See section 4.
Where logR'HK is known, ages in the original papers were derived
from their logR'HK-age relations. See the Appendix.
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History:
From electronic version for table 6.
Table 4 sent by the author.
Acknowledgements:
Marusa Zerjal [FMF (Fakulteta za Matematiko in Fiziko), Ljubljana]
who provided us the table 4.
References:
Zerjal et al. Paper I. 2013ApJ...776..127Z 2013ApJ...776..127Z
(End) Marusa Zerjal [FMF], Emmanuelle Perret [CDS] 09-Oct-2017