2006AJ....131.1806R


Query : 2006AJ....131.1806R

2006AJ....131.1806R - Astron. J., 131, 1806-1815 (2006/March-0)

The first high-resolution spectra of 1.3 L subdwarfs.

REINERS A. and BASRI G.

Abstract (from CDS):

We present the first high-resolution (R~31,000) spectra of the cool L subdwarf (sdL) 2MASS 0532+8246 and what was originally identified as an early-type sdL, LSR 1610-0040. Our work, in combination with contemporaneous work by Cushing and Vacca, makes it clear that the latter object is more likely a mid-M dwarf with an unusual composition that gives it some subdwarf spectral features. We use the data to derive precise radial velocities for both objects and to estimate space motion; both are consistent with halo kinematics. We measure the projected rotational velocities, revealing a very slow rotation for the old sd?M6 object LSR 1610-0040. The object 2MASS 0532+8246 exhibits a rapid rotation of vsini=65±15 km/s, consistent with the behavior of L dwarfs. This means that the braking time for L dwarfs is extremely long, or that perhaps they never slow down. A detailed comparison of the atomic Rb and Cs lines with spectra of field L dwarfs shows that the spectral type 2MASS 0532+8246 is consistent with being mid- to late-L. The Rb I and K I lines of LSR 1610-0040 are like those of an early-L dwarf, but the Cs I line is like that of a mid-M dwarf. The appearance of the Ca II triplet in absorption in this object is very hard to understand if it is not at least as warm as M6. We explain these effects in a consistent way using a mildly metal-poor mid-M model. M subdwarfs have weak metal oxides and enhanced metal hydrides relative to normal M dwarfs. LSR 1610-0040 exhibits metal hydrides like an M dwarf but metal oxides like a subdwarf. The same explanation that resolves the atomic-line discrepancy explains this as well. Our spectra cover the spectral region around a previously unidentified absorption feature at 9600 Å and the region around 9400 Å in which detection of TiH has been claimed. We identify the absorption around 9600 Å as being due to atomic lines of Ti and a small contribution of FeH, but we cannot confirm a detection of TiH in the spectra of cool sdLs. In 2MASS 0532+8246, both metal oxides and metal hydrides are extremely strong relative to normal L dwarfs. It may be possible to explain the strong oxide features in 2MASS 0532+8246 by invoking effects due to inhibited dust formation. High-resolution spectroscopy has aided in beginning to understand the complex molecular chemistry and spectral formation in metal-deficient and ultracool atmospheres and the properties of early ultra-low-mass objects.

Abstract Copyright:

Journal keyword(s): Stars: Chemically Peculiar - stars: individual (LSR J1610-0040) - stars: individual (2MASS J05325346+8246465) - Stars: Low-Mass, Brown Dwarfs - Stars: Subdwarfs

CDS comments: Par. 5.3.1., LSR 142+7102 is a misprint for 1425+7102 (LSR J1425+7102)

Simbad objects: 15

goto Full paper

goto View the references in ADS

Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * zet Cas Pu* 00 36 58.2841866 +53 53 48.867311 2.58 3.47 3.66 3.74 3.95 B2IV 429 0
2 DENIS J020529.0-115925 BD* 02 05 29.40072 -11 59 29.6736           L7V 142 0
3 2MASS J05325346+8246465 BD* 05 32 54.4385958315 +82 46 45.174215154           esdL7 55 0
4 Ross 619 PM* 08 11 57.5595749358 +08 46 22.983154927   14.60 12.834 12.527   M4.5Ve 175 0
5 G 51-15 Er* 08 29 49.3528237575 +26 46 33.626773321   16.87   14.736   M6.5Ve 262 0
6 LP 666-9 LM* 08 53 36.1607609203 -03 29 32.201339067     18.959 16.781 14.487 M9Ve 231 0
7 SSSPM J1013-1356 LM* 10 13 07.3466815701 -13 56 21.261098713       18.73 16.01 sdM9.5 35 0
8 LP 848-42 PM* 10 39 13.6431037309 -26 01 37.159273825   18.5       ~ 10 0
9 Wolf 359 Er* 10 56 28.9208702274 +07 00 53.003285286 16.706 15.541 13.507 11.684 9.507 dM6 649 0
10 LSPM J1425+7102 LM* 14 25 05.0227940507 +71 02 09.678947111   20.8   18.61 16.21 sdM8 29 0
11 2MASS J14392836+1929149 BD* 14 39 28.36896 +19 29 14.9820           L1V 120 0
12 SSSPM J1444-2019 PM* 14 44 20.67432 -20 19 22.2708       18.57 14.97 M9.0VI: 25 0
13 LSR J1610-0040 LM* 16 10 28.9562440851 -00 40 53.300190959       17.51 14.81 sdM6.5 48 0
14 2MASS J16262034+3925190 BD* 16 26 20.1331562643 +39 25 19.489643721       19.67 16.68 esdL4 44 0
15 G 227-29 PM* 18 22 27.14136 +62 03 01.9512   14.8   12.2   M4.0V 70 0

To bookmark this query, right click on this link: simbad:objects in 2006AJ....131.1806R and select 'bookmark this link' or equivalent in the popup menu


2021.10.21-00:27:14

© Université de Strasbourg/CNRS

    • Contact