2014A&A...572A..67Z


Query : 2014A&A...572A..67Z

2014A&A...572A..67Z - Astronomy and Astrophysics, volume 572A, 67-67 (2014/12-1)

Spectroscopic follow-up of L- and T-type proper-motion member candidates in the Pleiades.

ZAPATERO OSORIO M.R., BEJAR V.J.S., MARTIN E.L., GALVEZ ORTIZ M.C., REBOLO R., BIHAIN G., HENNING Th., BOUDREAULT S., GOLDMAN B., MUNDT R., CABALLERO J.A. and MILES-PAEZ P.A.

Abstract (from CDS):

We report on the near-infrared (JHK-bands) low-resolution spectroscopy and red optical (Z-band) photometry of seven proper-motion, very low-mass substellar member candidates of the Pleiades cluster with magnitudes in the interval J=17.5-20.8 and K=16.1-18.5mag. Spectra were acquired for six objects with the LIRIS and NIRSPEC instruments mounted on the 4.2-m William Herschel and the 10-m Keck II telescopes, respectively. Z-band images of two of the faintest candidates were collected with the ACAM instrument on the WHT. The new data confirm the low temperatures of all seven Pleiades proper motion candidates. From the imaging observations, we find extremely red Z-J and Z-K colors that suggest that the faintest target, Calar Pleiades 25, has a Galactic rather than extragalactic nature. We tentatively classify the spectroscopic targets from early-L to ∼T0 and suggest that the L/T transition, which accounts for the onset of methane absorption at 2.1 µm, may take place at J≃20.3 and K≃17.8mag in the Pleiades (absolute values of MJ≃14.7 and MK≃12.2mag). We find evidence of likely low-gravity atmospheres based on the presence of triangular-shape H-band fluxes and the high flux ratio K/H (compatible with red H-K colors) of Calar Pleiades 20, 21, and 22, which is a feature also seen in field low-gravity dwarfs. Weak Ki absorption lines at around 1.25µm are probably seen in two targets. These observations add support to the cluster membership of all seven objects in the Pleiades. The trend delineated by the spectroscopic sequence of Pleiades late-M and L dwarfs resembles that of the field. With masses estimated at 0.012-0.015M (solar metallicity and 120Myr), Calar Pleiades 20 (L6±1), 21 (L7±1), and 22 (L/T) may become the coolest and least massive Pleiades members that are corroborated with photometry, astrometry, and spectroscopy. Calar Pleiades 25 (<0.012M) is a firm free-floating planetary-mass candidate in the Pleiades.

Abstract Copyright:

Journal keyword(s): stars: low-mass - brown dwarfs - stars: late-type - open clusters and associations: individual: Pleiades

Simbad objects: 16

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Number of rows : 16
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 2MASS J00452143+1634446 BD* 00 45 21.4152609704 +16 34 44.736014164           L2beta 54 0
2 UGCS J034533.30+233434.2 * 03 45 33.300 +23 34 34.30           ~ 4 0
3 Cl* Melotte 22 NPNPL 4 * 03 45 58.480 +23 41 53.90           ~ 4 0
4 Cl* Melotte 22 CALAR 22 PM* 03 46 00.39 +23 19 33.9           ~ 4 0
5 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3208 0
6 Cl* Melotte 22 CALAR 21 * 03 47 00.36 +23 21 56.8           ~ 4 0
7 UGCS J034746.77+253516.5 * 03 47 46.780 +25 35 16.60           ~ 3 0
8 UGCS J034815.64+255008.9 PM* 03 48 15.650 +25 50 08.90           ~ 5 0
9 Cl* Melotte 22 CALAR 25 PM* 03 48 26.62 +22 51 53.9           ~ 3 0
10 2MASS J03552337+1133437 BD* 03 55 23.3735910810 +11 33 43.797034332           L5gamma 98 0
11 2MASSI J0423485-041403 BD* 04 23 48.5763811987 -04 14 03.246502948           L6.5+T2 113 0
12 2MASS J09083803+5032088 BD* 09 08 38.0091771633 +50 32 08.205341214           L8 36 0
13 G 196-3B BD* 10 04 20.6391105792 +50 22 59.378638152           L3beta 95 0
14 SIPS J1228-1547 BD* 12 28 15.23184 -15 47 34.2312       20.187 18.163 L5.5+L5.5 139 0
15 NAME Upper Sco Association As* 16 12 -23.4           ~ 1205 1
16 2MASSW J2224438-015852 BD* 22 24 43.8544128559 -01 58 53.284975671           L4.5V 115 0

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2022.08.12-07:40:15

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