J/A+A/567/A55 Metallicity of the γ Vel cluster (Spina+, 2014)
The Gaia-ESO Survey: the first abundance determination of the pre-main-sequence
cluster Gamma Velorum.
Spina L., Randich S., Palla F., Sacco G.G., Magrini L., Franciosini E.,
Morbidelli L., Prisinzano L., Alfaro E.J., Biazzo K., Frasca A.,
Gonzalez Hernandez J.I., Sousa S.G., Adibekyan V., Delgado-Mena E.,
Montes D., Tabernero H., Klutsch A., Gilmore G., Feltzing S.,
Jeffries R.D., Micela G., Vallenari A., Bensby T., Bragaglia A.,
Flaccomio E., Koposov S., Lanzafame A.C., Pancino E., Recio-Blanco A.,
Smiljanic R., Costado M.T., Damiani F., Hill V., Hourihane A., Jofre P.,
de Laverny P., Masseron T., Worley C.
<Astron. Astrophys. 567, A55 (2014)>
=2014A&A...567A..55S 2014A&A...567A..55S
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Abundances, [Fe/H] ;
Effective temperatures ; Equivalent widths ; Radial velocities ;
Spectroscopy
Keywords: stars: abundances - stars: pre-main sequence -
open clusters and associations: individual: gamma Velorum -
techniques: spectroscopic
Abstract:
Knowledge of the abundance distribution of star forming regions and
young clusters is critical to investigate a variety of issues, from
triggered star formation and chemical enrichment by nearby supernova
explosions to the ability to form planetary systems. In spite of this,
detailed abundance studies are currently available for relatively few
regions.
In this context, we present the analysis of the metallicity of the
Gamma Velorum cluster, based on the products distributed in the first
internal release of the Gaia-ESO Survey.
The Gamma Velorum candidate members have been observed with FLAMES,
using both UVES and Giraffe, depending on the target brightness and
spectral type. In order to derive a solid metallicity determination
for the cluster, membership of the observed stars must be first
assessed. To this aim, we use several membership criteria including
radial velocities, surface gravity estimates, and the detection of the
photospheric lithium line.
Out of the 80 targets observed with UVES, we identify 14
high-probability members. We find that the metallicity of the cluster
is slightly sub-solar, with a mean [Fe/H]=-0.057±0.018dex.
Although J08095427-4721419 is one of the high-probability members, its
metallicity is significantly larger than the cluster average. We
speculate about its origin as the result of recent accretion episodes
of rocky bodies of about 60 Msun hydrogen-depleted material from the
circumstellar disc.
Description:
Atmospheric parameters, radial velocities, lithium equivalent widths
are products of the Gaia-ESO Survey that were used for our membership
analysis of the 48 UVES targets observed in the Gamma Velorum fields.
Also photometry from Jeffries et al. (2009MNRAS.393..538J 2009MNRAS.393..538J) has been
used. Iron abundances of these stars have been used to determine the
metal content of the cluster. We also discussed the metallicity
derived through the iron abundances of the 208 cluster members
targeted with GIRAFFE and identified by Jeffries et al.
(2014A&A...563A..94J 2014A&A...563A..94J). Stellar parameters of 39 stars targeted by both
UVES and GIRAFFE have been used to check the quality of the data.
Objects:
------------------------------------------------------------
RA (2000) DE Designation(s)
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08 09.5 -47 54 Gamma Velorum = NAME GAM VEL CLUSTER
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 74 80 Stellar parameters of the 80 UVES targets
table5.dat 44 80 Quantities used for the membership analysis
table6.dat 46 39 Stellar parameters of the 39 stars targeted by
both UVES and GIRAFFE
table7.dat 71 208 Stellar parameters of the 208 GIRAFFE members
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See Also:
J/MNRAS/393/538 : Stellar association around gamma Vel (Jeffries+, 2009)
J/A+A/563/A94 : Kinematics of the Gamma Vel cluster (Jeffries+, 2014)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID [1/80] Identification number
4- 19 A16 --- CName Target Name in the Gaia-ESO archive,
HHMMSSss+DDMMSSs
21- 22 I2 h RAh Right ascension (J2000)
24- 25 I2 min RAm Right ascension (J2000)
27- 31 F5.2 s RAs Right ascension (J2000)
33 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 44 F4.1 arcsec DEs Declination (J2000)
46- 49 I4 K Teff ? Effective temperature
51- 53 I3 K e_Teff ? Standard error on effective temperature
55- 58 F4.2 [cm/s2] logg ? Logarithm of gravity
60- 63 F4.2 [cm/s2] e_logg ? Standard error on the logarithm of gravity
65- 69 F5.2 [Sun] [Fe/H] ? Iron abundance relative to the Sun
71- 74 F4.2 [Sun] e_[Fe/H] ? Standard error on iron abundance
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- ID [1/80] Identification number
4- 8 F5.1 km/s HRV ? Mean heliocentric radial velocity (1)
10 A1 --- l_EWLi Limit flag on EWLi
12- 14 I3 0.1nm EWLi Equivalent width of the 6708Å Li line
16- 17 I2 0.1nm e_EWLi ? Standard error on EWLi
19- 23 F5.2 mag (B-V)0 Derredenned B-V colour index (Johnson) (2)
25- 28 F4.2 mag VMAG0 Absolute derredenned V magnitude (Johnson) (2)
30- 32 A3 --- Mb1 [Y N SB2] Flag on membership based on RV (3)
34 A1 --- Mb2 [Y/N] Flag on membership based on logg (3)
36- 38 A3 --- Mb3 [Y N HCM] Flag on membership based on EWLi (3)
40 A1 --- Mb4 [Y/N] Flag on membership based on position in
color-magnitude diagram (3)
42- 44 A3 --- Mb [M N HCM ?] Flag on final membership (4)
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Note (1): Radial velocity values are not corrected for the 1.1km/s
systematic shift.
Note (2): The photometry is from Jeffries et al. (2009MNRAS.393..538J 2009MNRAS.393..538J),
dereddened adopting the E(B-V_ estimated for gamma Velorum by the same
authors.
Note (3): Flags on membership based on RV are:
Y = member
N = non-member
SB2 = double lined spectroscopic binary
HCM = hot candidate member
Note (4): Flags on final membership are:
M = member
N = non-member
HCM = hot candidate member
M? = likely member
? = unassigned membership
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- CName Target Name in the Gaia-ESO archive,
HHMMSSss+DDMMSSs
18- 21 I4 K Teff ? Effective temperature
23- 25 I3 K e_Teff ? Standard error on effective temperature
27- 30 F4.2 [cm/s2] logg ? Logarithm of gravity
32- 35 F4.2 [cm/s2] e_logg ? Standard error on the logarithm of gravity
37- 41 F5.2 [Sun] [Fe/H] ? Iron abundance relative to the Sun
43- 46 F4.2 [Sun] e_[Fe/H] ? Standard error on iron abundance
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- CName Target Name in the Gaia-ESO archive,
HHMMSSss+DDMMSSs
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 28 F5.2 s RAs Right ascension (J2000)
30 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 41 F4.1 arcsec DEs Declination (J2000)
43- 46 I4 K Teff ? Effective temperature
48- 50 I3 K e_Teff ? Standard error on effective temperature
52- 55 F4.2 [cm/s2] logg ? Logarithm of gravity
57- 60 F4.2 [cm/s2] e_logg ? Standard error on the logarithm of gravity
62- 66 F5.2 [Sun] [Fe/H] ? Iron abundance relative to the Sun
68- 71 F4.2 [Sun] e_[Fe/H] ? Standard error on iron abundance
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Acknowledgements:
Lorenzo Spina, lspina(at)arcetri.astro.it
(End) L. Spina [Osserv. Astrofisico di Arcetri], P. Vannier [CDS] 07-May-2014