J/A+A/640/A9 Open star cluster Coma Berenices multi-photometry (Martin+, 2020)
Search for the sub-stellar lithium depletion boundary in the open star cluster
Coma Berenices.
Martin E.L., Lodieu N., Bejar V.J.S.
<Astron. Astrophys. 640, A9 (2020)>
=2020A&A...640A...9M 2020A&A...640A...9M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, infrared ; Photometry, SDSS
Keywords: brown dwarfs -
open clusters and association: individual: Coma Berenices -
techniques: spectroscopic - open clusters and association: general -
stars: abundances
Abstract:
We mainly aim to search for the lithium depletion boundary (LDB) among
the sub-stellar population of the open star cluster Coma Berenices.
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).
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.
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 550Myr 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.
Description:
List of member candidates of Coma Ber with UKIDSS GCG DR9 (Cat.
II/319/), Pan-STARR DR1 (Cat. II/349) and SDSS DR12 (Cat. V/147)
photometry.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 118 34 List of Coma Ber photometric member candidates
identified in the area common to the three
large-scale public surveys considered in this work
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID UKIDSS GCS ID number
6- 7 I2 h RAh Rigth ascension (J2000)
9- 10 I2 min RAm Rigth ascension (J2000)
12- 15 F4.1 s RAs Rigth ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 27 F4.1 arcsec DEs Declination (J2000)
29- 34 F6.3 mag Zmag UKIDSS GCG DR9 Z magnitude
36- 41 F6.3 mag Ymag UKIDSS GCG DR9 Y magnitude
43- 48 F6.3 mag Jmag UKIDSS GCG DR9 J magnitude
50- 55 F6.3 mag Hmag UKIDSS GCG DR9 H magnitude
57- 62 F6.3 mag Kmag UKIDSS GCG DR9 K magnitude
64- 69 F6.3 mag imagPS Pan-STARR DR1 i magnitude
71- 76 F6.3 mag zmagPS Pan-STARR DR1 z magnitude
78- 83 F6.3 mag ymagPS Pan-STARR DR1 y magnitude
85- 90 F6.3 mag umag ? SDSS DR12 u magnitude
92- 97 F6.3 mag gmag ? SDSS DR12 g magnitude
99-104 F6.3 mag rmag ? SDSS DR12 r magnitude
106-111 F6.3 mag imag ? SDSS DR12 i magnitude
113-118 F6.3 mag zmag ? SDSS DR12 z magnitude
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 21-Jul-2020