2020A&A...640A...9M


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.26CET14:41:17

2020A&A...640A...9M - Astronomy and Astrophysics, volume 640A, 9-9 (2020/8-1)

Search for the sub-stellar lithium depletion boundary in the open star cluster Coma Berenices.

MARTIN E.L., LODIEU N. and BEJAR V.J.S.

Abstract (from CDS):


Aims. We mainly aim to search for the lithium depletion boundary (LDB) among the sub-stellar population of the open star cluster Coma Berenices.
Methods. Since the number of brown dwarf candidates in Coma Ber available in the literature is scarce, we carried out a search for additional candidates photometrically using colour-magnitude diagrams combining optical and infrared photometry from the latest public releases of the following large-scale surveys: the United Kingdom InfraRed Telescope Infrared Deep Sky Survey (UKIRT/UKIDSS), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), the Sloan Digital Sky Survey (SDSS), and AllWISE. We checked astrometric consistency with cluster membership using Gaia DR2. A search for Li in three new and five previously known brown dwarf candidate cluster members was performed via spectroscopic observations using the OSIRIS instrument at the 10.4m Gran Telescopio de Canarias (GTC).
Results. A couple dozen new photometric candidate brown dwarfs located inside the tidal radius of Coma Ber are reported, but none of these are significantly fainter and cooler than previously known members. No LiI resonance doublet at 6707.8Å was detected in any of eight Coma Ber targets in the magnitude range J=15-19 and G=20-23 observed with the GTC. Spectral types and radial velocities were derived from the GTC spectra. These values confirm the cluster membership of four L2-L2.5 dwarfs, two of which are new in the literature.
Conclusions. The large Li depletion factors found among the four bona fide sub-stellar members in Coma Ber implies that the LDB must be located at spectral type later than L2.5 in this cluster. Using the latest evolutionary models for brown dwarfs, a lower limit of 550 Myr on the cluster age is set. This constraint has been combined with other dating methods to obtain an updated age estimate of 780±230Myr for the Coma Ber open cluster. Identification of significantly cooler sub-stellar cluster members in Coma Ber awaits the advent of the Euclid wide survey, which should reach a depth of about J=23; this superb sensitivity will make it possible to determine the precise location of the sub-stellar LDB in this cluster and to carry out a complete census of its sub-stellar population.

Abstract Copyright: © ESO 2020

Journal keyword(s): brown dwarfs - open clusters and associations: individual: Coma Berenices - techniques: spectroscopic - open clusters and associations: general - stars: abundances

VizieR on-line data: <Available at CDS (J/A+A/640/A9): table1.dat>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

CDS comments: Cbd NN objects not in SIMBAD. Objects from Tang et al. 2018 not in SIMBAD.

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Cl Blanco 1 OpC 00 04 07 -29 50.0           ~ 241 0
2 * alf Per V* 03 24 19.3700924 +49 51 40.245455 2.64 2.27 1.79     F5Ib 804 1
3 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 3024 0
4 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2695 0
5 HD 289002 * 06 45 13.3726265810 +02 08 14.688016523 10.06 10.62 10.44     B1 229 0
6 NGC 2547 OpC 08 09 52.360 -49 10 35.01           ~ 317 0
7 NGC 2632 OpC 08 40 24 +19 40.0           ~ 1259 0
8 IC 2391 OpC 08 40 32 -53 02.0           ~ 723 0
9 IC 2602 OpC 10 42 58 -64 24.0           ~ 557 0
10 SDSS J121832.69+273731.1 BD* 12 18 32.696 +27 37 31.14           L1 3 0
11 Cl* Melotte 111 AV 1491 * 12 24 53.5834343496 +23 43 05.028178400   12.08 11.24 10.83 10.34 K2.2 4 0
12 Cl Melotte 111 OpC 12 25 06.00 +26 06 00.0           ~ 413 0
13 BD+24 2462 * 12 27 20.6894688524 +23 19 47.457446293   11.12 10.32 9.83 9.46 G7.9 17 0
14 DENIS J122815.2-154733 BD* 12 28 15.23184 -15 47 34.2312       20.187 18.163 L5.5+L5.5 135 0
15 Cl* Melotte 111 AV 1798 * 12 28 34.2903854047 +23 32 30.558968731   11.89 10.96 10.40 9.97 ~ 3 0
16 Cl* Melotte 111 AV 2129 * 12 33 00.6266739376 +27 42 44.760989819   12.42 11.18 10.42 9.80 K2.9 14 0
17 Ross 640 WD* 16 28 25.0030292072 +36 46 15.849157470   14.01   13.9   DZ6 172 0
18 IC 4665 OpC 17 46 18 +05 43.0           ~ 317 0

    Equat.    Gal    SGal    Ecl

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2020.10.26-14:41:17

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