2006A&A...460..547G


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.03CET19:23:24

2006A&A...460..547G - Astronomy and Astrophysics, volume 460, 547-553 (2006/12-3)

Accretion in ρ Ophiuchus brown dwarfs: infrared hydrogen line ratios.

GATTI T., TESTI L., NATTA A., RANDICH S. and MUZEROLLE J.

Abstract (from CDS):

Mass accretion rate determinations are fundamental for an understanding of the evolution of pre-main sequence star circumstellar disks. Magnetospheric accretion models are used to derive values of the mass accretion rates in objects of very different properties, from brown dwarfs to intermediate-mass stars; we test the validity of these models in the brown dwarf regime, where the stellar mass and luminosity, as well as the mass accretion rate, are much lower than in T Tauri stars. We have measured nearly simultaneously two infrared hydrogen lines, Paβ and Brγ, in a sample of 16 objects in the star-forming region ρ-Oph. The sample includes 7 very low mass objects and brown dwarfs and 9 T Tauri stars. Brown dwarfs where both lines are detected have a ratio Paβ/Brγ of ∼2. Larger values, >3.5, are only found among the T Tauri stars. The low line ratios in brown dwarfs indicate that the lines cannot originate in the column of gas accreting from the disk onto the star along the magnetic field lines, and we suggest that they form instead in the shocked photosphere, heated to temperatures of ∼3500K. If so, in analogy to veiling estimates in T Tauri stars, the hydrogen infrared line fluxes may provide a reliable measure of the accretion rate in brown dwarfs.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - stars: formation - stars: low-mass, brown dwarfs

Simbad objects: 22

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Number of rows : 22

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 V* FS Tau Or* 04 22 02.1925017485 +26 57 30.331063489 17.57   14.10 15.63   M3.5e+M0e 261 0
2 V* DG Tau Or* 04 27 04.6913654419 +26 06 16.041555299 13.57 13.97 10.50 12.28   K6Ve 942 1
3 V* GI Tau Or* 04 33 34.0608378045 +24 21 17.067391746 14.34   13.70 12.15 11.06 K5Ve 257 1
4 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3577 0
5 BKLT J162538-242238 Y*O 16 25 38.1274702773 -24 22 36.198931346           M0 26 0
6 CRBR 2317.3-1925 Y*O 16 26 18.82056 -24 26 10.5216           M7 41 0
7 [GY92] 5 Y*O 16 26 21.5389368381 -24 26 01.000528521       18.30 15.80 M7 61 1
8 [RR90] Oph 2320.8-1721 Y*O 16 26 22.26912 -24 24 07.0632           M8 66 0
9 [GY92] 21 Y*O 16 26 23.57976 -24 24 39.4956           K7 64 2
10 BKLT J162656-241353 TT* 16 26 56.7840840242 -24 13 51.542985458       18.46 16.29 K7 26 0
11 [GY92] 204 TT* 16 27 06.5924723987 -24 41 48.883697790       17.57 15.43 M5 83 0
12 WL 17 Y*O 16 27 06.77616 -24 38 14.9964           ~ 89 0
13 WL 10 Y*O 16 27 09.1086301538 -24 34 08.290873154           K9 65 0
14 WL 11 Y*O 16 27 12.13128 -24 34 49.1412           M2 43 0
15 [GY92] 235 Y*O 16 27 13.8208549477 -24 43 31.648188013           M3.5 38 0
16 YLW 18 TT* 16 27 33.1158717225 -24 41 15.261194836       17.66 15.65 K5-K6 65 0
17 BKLT J162737-241756 Y*O 16 27 37.4272403427 -24 17 54.955552302           M7.5 26 0
18 YLW 47 TT* 16 27 38.3220493264 -24 36 58.601739078       17.69 15.52 M0 87 0
19 [GY92] 310 Y*O 16 27 38.6280925403 -24 38 39.230714152         17.40 M8 61 0
20 ROX 27 TT* 16 27 39.4297106587 -24 39 15.527875310       15.76 14.03 M0+M4 95 0
21 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3086 0
22 BKLT J162812-241138 Y*O 16 28 12.7237256177 -24 11 35.723756180           M6 27 0

    Equat.    Gal    SGal    Ecl

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2020.12.03-19:23:24

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