J/A+A/575/A4 Activity and accretion in γ Vel and Cha I (Frasca+, 2015)
The Gaia-ESO Survey: chromospheric emission, accretion properties, and rotation
in gamma Velorum and Chamaeleon I.
Frasca A., Biazzo K., Lanzafame A.C., Alcala J.M., Brugaletta E.,
Klutsch A., Stelzer B., Sacco G.G., Spina L., Jeffries R.D., Montes D.,
Alfaro E.J., Barentsen G., Bonito R., Gameiro J.F., Lopez-Santiago J.,
Pace G., Pasquini L., Prisinzano L., Sousa S.G., Gilmore G., Randich S.,
Micela G., Bragaglia A., Flaccomio E., Bayo A., Costado M.T.,
Franciosini E., Hill V., Hourihane A., Jofre P., Lardo C., Maiorca E.,
Masseron T., Morbidelli L., Worley C.C.
<Astron. Astrophys. 575, A4 (2015)>
=2015A&A...575A...4F 2015A&A...575A...4F
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Radial velocities ;
Rotational velocities ; Equivalent widths
Keywords: stars: chromospheres - stars: low-mass -
open clusters and associations: individual: gamma Velorum -
stars: rotation -
open clusters and associations: individual: Chamaelon I -
stars: pre-main sequence
Abstract:
We use the fundamental parameters (effective temperature, surface
gravity, lithium abundance, and radial velocity) delivered by the GES
consortium in the first internal data release to select the members of
Gamma Vel and Cha I among the UVES and GIRAFFE spectroscopic
observations. A total of 140 Gamma Vel members and 74 Cha I members
were studied.
The procedure adopted by the GES to derive stellar fundamental
parameters provided also measures of the projected rotational velocity
(vsini). We calculated stellar luminosities through spectral energy
distributions, while stellar masses were derived by comparison with
evolutionary tracks. The spectral subtraction of low-activity and
slowly rotating templates, which are rotationally broadened to match
the vsini of the targets, enabled us to measure the equivalent widths
(EWs) and the fluxes in the Hα and Hβ lines. The Hα
line was also used for identifying accreting objects, on the basis of
its equivalent width and the width at the 10% of the line peak (10%W),
and for evaluating the mass accretion rate (Macc).
The distribution of vsini for the members of Gamma Vel displays a peak
at about 10km/s with a tail toward faster rotators. There is also
some indication of a different vsini distribution for the members of
its two kinematical populations. Most of these stars have Hα
fluxes corresponding to a saturated activity regime. We find a similar
distribution, but with a narrower peak, for Cha I.
Only a handful of stars in Gamma Vel display signatures of accretion,
while many more accretors were detected in the younger Cha I, where
the highest Hα fluxes are mostly due to accretion, rather than
to chromospheric activity. Accreting and active stars occupy two
different regions in a T_eff-flux diagram and we propose a criterion
for distinguishing them. We derive M_acc in the ranges
10-11-10-9M☉/yr and 10-10-10-7M☉/yr for Gamma Vel
and Cha I accretors, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 193 140 Parameters of the Gamma Vel members
table3.dat 193 74 Parameters of the Cha I members
table4.dat 42 294 Elodie templates
table5.dat 70 20 Hβ equivalent widths and fluxes
from UVES spectra
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/563/A94 : Kinematics of the Gamma Vel cluster (Jeffries+, 2014)
J/A+A/461/669 : XMM observations of Cha I dark cloud (Robrade+, 2007)
J/ApJ/675/1375 : IRAC/MIPS photometry in Cha I (Luhman+, 2008)
J/ApJ/686/1195 : IR photometry in the γ Vel cluster (Hernandez+, 2008)
J/MNRAS/393/538 : Stellar association around gamma Vel (Jeffries+, 2009)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 18 A17 --- 2MASS 2MASS designation (HHMMSSss+DDMMSSs, J2000)
21- 22 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
29- 33 F5.2 s RAs Right ascension (J2000)
36 A1 --- DE- Declination sign
37- 38 I2 deg DEd Declination (J2000)
41- 42 I2 arcmin DEm Declination (J2000)
45- 48 F4.1 arcsec DEs Declination (J2000)
50- 56 F7.3 km/s HRV ?=- Heliocentric radial velocity
59- 64 A6 --- SpT Spectral type (MK or HD)
66- 70 I5 K Teff [3257/6501] Effective temperature
73- 75 I3 K e_Teff [30/498] Effective temperature error
78- 82 F5.1 km/s vsini [0/176] Projected rotational velocity
85- 88 F4.1 km/s e_vsini [0.5/55] Projected rotational velocity error
90- 96 F7.3 0.1nm EWHa [0/223]?=- Hα equivalent width (Å)
98-103 F6.3 0.1nm e_EWHa [0.01/16]?=- Hα equivalent width error
106-112 E7.3 mW/m2 FHa ?=- Hα flux
115-121 E7.3 mW/m2 e_FHa ?=- Hα flux error
124-127 F4.2 --- r [0/3] Veiling
130-133 F4.2 --- e_r [0/0.6] Veiling error
136-141 F6.2 km/s W10Ha [98/567]?=- Hα full width at 10% of the
peak level
144-149 F6.2 km/s e_W10Ha [0/116]?=- Error of W10Ha
152-157 F6.4 Lsun L [0.04/5.2]?=- Stellar luminosity
160-165 F6.4 Lsun e_L [0.008/2.3]?=- Stellar luminosity error
168-171 F4.2 Msun M [0.2/1.6]?=- Stellar mass
173-178 F6.2 [Msun/yr] Macc1 [-11/-7]?=- Log of mass accretion rate
from W10Ha
181-186 F6.2 [Msun/yr] Macc2 [-11/-7]?=- Log of mass accretion rate
from EWHa
189 A1 --- S [GU] Spectrograph (G=GIRAFFE, U=UVES)
192-193 A2 --- Note Note on star (1)
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Note (1): Notes as follows:
PT = Photometric temperature derived as in Lanzafame et al.
(2015, A&A in press)
PA = Possible accretor
SV = Strongly veiled. RV measured from the centroid of the Lithium 6708 line
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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2- 10 A9 --- Name Star name
14- 21 A8 --- SpT Spectral type in MK or HD
23- 27 I5 K Teff [2979/9164] Effective temperature
30- 34 F5.2 [cm/s2] logg [-0.5/5.2] Logarithm of gravity
38- 42 F5.2 [Sun] [Fe/H] [-2.8/1.1] Iron abundance relative to the Sun
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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2- 18 A17 --- 2MASS 2MASS designation
22- 27 F6.3 0.1nm EWHb [0.03/17] Hβ equivalent width (Å)
31- 36 F6.3 0.1nm e_EWHb [0.01/2] Hβ equivalent width error
40- 46 E7.3 mW/m2 FHb Hβ flux
51- 57 E7.3 mW/m2 e_FHb Hβ flux error
61- 70 A10 --- Cluster Cluster name (Cha I or Gamma Vel)
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Acknowledgements:
Antonio Frasca, antonio.frasca(at)oact.inaf.it
History:
* 12-Dec-2014: original version from author
* 11-Jul-2015: in table5, 2MASS names to conform to table3 and 2MASS:
J11100704-7629377 transformed into J11100704-7629376;
J11092378-7623207 transformed into J11092379-7623207
(End) Antonio Frasca [INAF-OACt, Italy], Patricia Vannier [CDS] 12-Dec-2014