J/A+A/574/L7 Gaia-ESO Survey: Li-rich stars in NGC2547 (Sacco+, 2015)
The Gaia-ESO Survey: discovery of a spatially extended low-mass population in
the Vela OB2 association.
Sacco G.G., Jeffries R.D., Randich S., Franciosini E., Jackson R.J.,
Cottaar M., Spina L., Palla F., Mapelli M., Alfaro E.J., Bonito R.,
Damiani F., Frasca A., Klutsch A., Lanzafame A., Bayo A., Barrado D.,
Jimenez-Esteban F., Gilmore G., Micela M., Vallenari A., Allende-Prieto C.,
Flaccomio E., Carraro G., Costado M.T., Jofre P., Lardo C., Magrini L.,
Morbidelli L., Prisinzano L., Sbordone L.
<Astron. Astrophys. 574, L7 (2015)>
=2015A&A...574L...7S 2015A&A...574L...7S
ADC_Keywords: Clusters, open ; Stars, S ; Photometry, VRI ; Spectroscopy ;
Space velocities
Keywords: stars: formation - stars: pre-main sequence -
techniques: spectroscopic -- open clusters and association: Vela OB2 -
open clusters and association: NGC 2547 -
stars: individual: gamma2 Velorum
Abstract:
The nearby (distance ∼350-400pc), rich Vela OB2 association, includes
gamma2 Velorum, one of the most massive binaries in the solar
neighborhood, and is an excellent laboratory for investigating the
formation and early evolution of young clusters. Recent Gaia-ESO
survey observations led to the discovery of two kinematically distinct
populations in the young (10-15Myr) cluster immediately surrounding
gamma2 Velorum. Here we analyse the results of Gaia-ESO survey
observations of NGC 2547, a 35Myr cluster located two degrees south of
gamma2 Velorum. The radial velocity distribution of lithium-rich
pre-main sequence stars shows a secondary population, kinematically
distinct and younger than NGC 2547. The radial velocities, lithium
absorption lines, and the positions in a color-magnitude diagram of
this secondary population are consistent with those of one of the
components discovered around gamma2 Velorum. This result shows that
there is a young, low-mass stellar population spread over at least
several square degrees in the Vela OB2 association. This population
could have originally been part of a cluster around gamma2 Velorum
that expanded after gas expulsion, or formed in a less dense
environment spread over the whole Vela OB2 region.
Description:
Main properties of the Li-rich stars in the field of view of the open
clusters NGC 2547 observed by the Gaia-ESO Survey. The Table include
coordinates, photometry from the literature, spectroscopic data
derived by the Gaia-ESO observations, and the probability for a star
to be part of the primary population of NGC 2547.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 75 Lithium rich stars in NGC 2547
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See also:
I/324 : The Initial Gaia Source List (IGSL) (Smart, 2013)
VI/137 : GaiaSimu Universe Model Snapshot (Robin+, 2012)
J/A+A/561/A94 : Velocities and photometry in Trumpler 20 (Donati+, 2014)
J/A+A/563/A94 : Kinematics of the Gamma Vel cluster (Jeffries+, 2014)
J/A+A/566/A50 : Classification of stellar spectra 644-681nm (Damiani+, 2014)
J/A+A/567/A55 : Metallicity of the gamma Velorum cluster (Spina+, 2014)
J/A+A/569/A17 : Gaia-ESO Survey: NGC 6705 (Cantat-Gaudin+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right ascension (J2000)
11- 19 F9.5 deg DEdeg Declination (J2000)
21- 25 F5.2 mag Vmag [11.7/19.5]? Johnson V magnitude (1)
27- 31 F5.2 mag Rcmag [11.4/18.6]? Cousins R magnitude (2)
33- 37 F5.2 mag Icmag [11.2/16.8]Cousins I magnitude (2)
39- 43 F5.1 0.1pm EW(Li) [101/559] Equivalent width of the Li line
at 670.8nm (in mÅ)
45- 49 F5.2 km/s HRV [-9/63] Heliocentric radial velocity (3)
51- 54 F4.2 km/s e_HRV [0.1/1.1] Error on HRV (3)
56- 59 F4.2 --- p(A) [0/1]? Probability to belong to NGC 2547A (4)
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Note (1): V photometry from Naylor et al. (2002MNRAS.335..291N 2002MNRAS.335..291N).
Note (2): Rc and Ic photometry from Jeffries et al. (2004MNRAS.351.1401J 2004MNRAS.351.1401J).
Note (3): Radial Velocities and their errors derived from the Gaia-ESO spectra
as described in Jeffries et al. (2014A&A...563A..94J 2014A&A...563A..94J, Cat. J/A+A/563/A94).
In case of multi-epoch observations the RV has been calculated as the weighted
mean of multiple measurements.
Note (4): Probability of belonging to population A of NGC 2547 derived from the
RV, according to the best fit of the RV distribution with a model, assuming
the presence of two populations: the 35 Myr cluster NGC 2547 and to the
younger cluster γ Vel B. The probability to be part of γ Vel B
is equal to 1-p(A). Stars outside of the radial velocity range 5<RV<30km/s
have not been considered in the fit.
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Acknowledgements:
Giuseppe Germano Sacco, gsacco(at)arcetri.inaf.it,
INAF, Osservatorio Astrofisico di Arcetri
References:
Gilmore et al., 2012Msngr.147...25G 2012Msngr.147...25G, The Gaia ESO Survey
(End) Giuseppe Sacco [INAF], Patricia Vannier [CDS] 24-Dec-2014