J/A+A/623/A159 NGC6530 member parameters from Gaia-ESO survey (Prisinzano+ 2019)
The Gaia-ESO Survey: Age spread in the star forming region NGC6530 from the
HR diagram and gravity indicators.
Prisinzano L., Damiani F., Kalari V., Jeffries R., Bonito R., Micela G.,
Wright N.J., Jackson R.J., Tognelli E., Guarcello M.G., Vink J.S.,
Klutsch A., Jimenez-Esteban F.M., Roccatagliata V., Tautvaisiene G.,
Gilmore G., Randich S., Alfaro E.J., Flaccomio E., Koposov S., Lanzafame A.,
Pancino E., Bergemann M., Carraro G., Franciosini E., Frasca A., Gonneau A.,
Hourihane A., Jofre P., Lewis J., Magrini L., Monaco L., Morbidelli L.,
Sacco G.G., Worley C.C., Zaggia S.
<Astron. Astrophys. 623, A159 (2019)>
=2019A&A...623A.159P 2019A&A...623A.159P (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, ages ; Stars, pre-main sequence ;
Spectroscopy ; Photometry, VRI
Keywords: accretion - accretion disks - techniques: spectroscopic -
stars: formation - Hertzsprung-Russell and C-M diagrams -
stars: pre-main sequence -
open clusters and associations: individual: NGC 6530
Abstract:
In very young clusters, stellar age distribution is the empirical
proof of the duration of star formation (SF) and of the physical
mechanisms involved in the process. We derived accurate stellar ages
for the cluster NGC6530, associated with the Lagoon Nebula to infer
its SF history. We use the Gaia-ESO survey observations and Gaia DR2
data, to derive cluster membership and fundamental stellar parameters.
We identified 652 confirmed and 9 probable members. The reddening
inferred for members and non-members allows us to distinguish MS stars
and giants, in agreement with the distances inferred from Gaia DR2
data. The foreground and background stars show a spatial pattern that
traces the 3D structure of the nebular dust component. We derive
stellar ages for 382 confirmed cluster members and we find that the
gravity-sensitive gamma index distribution for M stars is correlated
with stellar age. For all members with Teff<5500K, the mean
logarithmic age is 5.84 (units of years) with a dispersion of 0.36dex.
The age distribution of stars with accretion and/or disk (CTTSe) is
similar to that of stars without accretion and without disk (WTTSp).
We interpret this dispersion as evidence of a real age spread since
the total uncertainties on age determinations, derived from Monte
Carlo simulations, are significantly smaller than the observed spread.
This conclusion is supported by the evidence of a decreasing of the
gravity-sensitive gamma index as a function of stellar ages. The
presence of the age spread is also supported by the spatial
distribution and the kinematics of old and young members. In
particular, members with accretion and/or disk, formed in the last
1Myr, show evidence of subclustering around the cluster center, in the
Hourglass Nebula and in the M8-E region, suggesting a possible
triggering of star formation events by the O-type star ionization
fronts.
Description:
We present stellar parameters of NGC6530 cluster members, derived by
using Gaia-ESO Survey data.
Table A1 presents literature optical photometry, Chandra X-ray
detection, heliocentric radial velocities and projected rotational
radial velocities. In addition, the equivalent width of the lithium
line and the full width half maximum of the Hα line, derived
from HR15N spectra acquired with ESO-VLT/FLAMES spectrograph of
cluster members, are given.
Table A2 presents the gravity gamma index and the effective
temperatures released by the Gaia-ESO survey and the kinematic
parameters (proper motions in RA and DE and parallaxes) from Gaia
DR2. Finally, the reddening E(V-I) derived by using spectroscopic
effective temperatures and observed colors are given together with the
logarithmic stellar ages derived by using the theoretical models and
the HR diagram. Members and probable members are classified as CCTSe
or WTTSp objects, as defined in the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 158 661 Literature data and Gaia-ESO survey parameters
of cluster members
tablea2.dat 141 661 Gaia-ESO survey and Gaia parameters, individual
reddenings and isochronal ages of members
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/430/941 : Star formation region NGC 6530 (Prisinzano+, 2005)
J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CName Target Name in the Gaia-ESO archive,
HHMMSSss+DDMMSSs
20- 35 A16 --- VPHAS+ VPHAS+ Target Name, HHMMSSss+DDMMSSs
39- 47 D9.5 deg RAdeg Right Ascension (J2000.0)
51- 59 D9.5 deg DEdeg Declination (J2000)
62- 67 F6.3 mag Vmag ? Apparent V magnitude
71- 75 F5.3 mag e_Vmag ? Error apparent V magnitude
78- 83 F6.3 mag Imag ? Apparent I magnitude
87- 91 F5.3 mag e_Imag ? Error apparent I magnitude
93- 99 F7.2 km/s HRV ? Heliocentric radial velocity
103-107 F5.2 km/s e_HRV ? rms uncertainty on HRV
110-115 F6.2 km/s vsini ? Projected rotational velocity
119-123 F5.2 km/s e_vsini ? rms uncertainty on vsini
126-131 F6.2 0.1pm EWLi ? 670.8nm Li equivalent width
134-139 F6.2 0.1pm e_EWLi ? rms uncertainty on EWLi
143-147 F5.2 0.1nm FWZI ? Full width zero intensity
152-155 F4.2 0.1nm e_FWZI ? rms uncertainty of FWZI
158 I1 --- fXrays [0/1]? X-ray membership flag (1)
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Note (1): flag of X-ray detection as follows:
0 = no detection
1 = detection
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CName Target Name in the Gaia-ESO archive
21- 24 F4.2 --- gamma ? Gravity index gamma
29- 32 F4.2 --- e_gamma ? rms uncertainty of gamma
35- 42 F8.2 K Teff ? effective temperature
46- 52 F7.2 K e_Teff ? Standard error of Teff
54- 60 F7.3 mas/yr pmRA* ? Gaia DR2 Proper motion in RA, pmRA*cosDE
63- 68 F6.3 mas/yr e_pmRA* ? Gaia DR2 Stand. error of pmRA*
71- 76 F6.3 mas/yr pmDE ? Gaia DR2 Proper Motion in DE
79- 84 F6.3 mas/yr e_pmDE ? Gaia DR2 Stand. error of pmDE
87- 92 F6.3 mas Plx ? Gaia DR2 parallax
95-100 F6.3 mas e_Plx ? Gaia DR2 Standard error of plx
104-108 F5.2 mag E(V-I) ? Color excess E(V-I)
113-116 F4.2 mag e_E(V-I) ? Standard error of E(V-I)
121-124 F4.2 [yr] t ? Logarithmic stellar age
129-132 F4.2 [yr] e_t ? Uncertainty of t
133-134 A2 --- fMem [M PM] Membership flag (2)
137-141 A5 --- ftype [CTTSe WTTSp] Member type (3)
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Note (2): Membership flag as follows:
M = confirmed member
PM = probable member
Note (3): Membership classification as follows:
CTTSe = Classical T-Tauri star with excess
WTTSp = Weak T-Tauri star with photospheric emission
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Acknowledgements:
Loredana Prisinzano, loredana.prisinzano(at)inaf.it
References:
Prisinzano et al., 2005A&A...430..941P 2005A&A...430..941P, Cat. J/A+A/430/941
The star formation region NGC 6530: Distance, ages and initial mass function
Gaia Collaboration, 2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345
Gaia Data Release 2. Summary of the contents and survey properties
Drew et al., 2014MNRAS.440.2036D 2014MNRAS.440.2036D, Cat. J/MNRAS/440/2036
The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge
(VPHAS+)
(End) Patricia Vannier CDS 20-Mar-2019