1997A&A...321..220B


Query : 1997A&A...321..220B

1997A&A...321..220B - Astronomy and Astrophysics, volume 321, 220-228 (1997/5-1)

Physical properties of 90AU to 250AU pre-main-sequence binaries.

BRANDNER W. and ZINNECKER H.

Abstract (from CDS):

We have analyzed photometric and spectroscopic data of a sample of 14 spatially resolved pre-main-sequence binaries (separations 0.6" to 1.7") in the nearby (150pc) low-mass star-forming regions of Chamaeleon, Lupus, and ρ Ophiuchi. The spectroscopic data have been obtained with the ESO New Technology Telescope (NTT) at La Silla under subarcsec seeing conditions. All binaries (originally unresolved) were identified as pre-main-sequence stars based on their strong Hα emission - which classifies them as classical T Tauri stars - and their association with dark clouds. One of the presumed binaries turned out to be a likely chance projection with the "primary" showing neither Hα emission nor Li absorption. Using the spectral A index (as defined by Kirkpatrick et al. 1991ApJS...77..417K), which measures the strength of the CaH band at 697.5nm relative to the nearby continuum, as a luminosity class indicator, we could show that the classical T Tauri stars in our sample tend to be close to luminosity class V. Eight out of the 14 pairs could be placed on an H-R diagram. A comparison with theoretical pre-main-sequence evolutionary tracks yields that for all pairs the individual components appear to be coeval within the observational errors. This finding is similar to Hartigan et al. (1994ApJ...427..961H) who detected that two third of the wider pairs with separations from 400AU to 6000AU are coeval. However, unlike Hartigan et al. for the wider pairs, we find no non-coeval pairs among our sample. Thus, the formation mechanism for a significant fraction of the wider pre-main-sequence binaries might be different from that of closer pre-main-sequence binaries. All of the latter appear to have formed simultaneously.

Abstract Copyright:

Journal keyword(s): stars: binaries: visual - stars: pre-main-sequence - T association: individual: Chamaeleon, Lupus cloud, rho Oph cloud

Nomenclature: Table 2: ESO-HA NNN (No. 281) added.

Simbad objects: 21

goto View the references in ADS

Number of rows : 21
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 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1058 1
2 ESO-HA 281 mul 11 07 03.485520 -76 31 44.15916   17.47 15.55 15.05 12.93 M4.5 8 0
3 V* VV Cha Or* 11 07 28.241088 -76 52 11.92620   16.00 14.72 14.48 12.19 M1.5+M3 62 0
4 V* VW Cha Or* 11 08 01.3974165580 -77 42 28.579297348 13.91 14.04 12.80   10.69 K7+M0 172 0
5 Sz 30 TT* 11 09 11.72304 -77 29 12.4836   14.89 13.28 13.02 11.032 M2.5+M2 51 0
6 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 739 0
7 NAME Cha II MoC 12 54 -77.2           ~ 313 0
8 RX J1300.9-7708 Y*O 13 00 53.46120 -77 09 08.6580           M1 23 0
9 V* BK Cha Or* 13 07 09.247848 -77 30 30.56004   16.11 14.58 14.41   K7 31 0
10 Sz 62 Y*O 13 09 50.37 -77 57 24.0   16.99 15.55     M2.5 31 0
11 NAME Lupus Complex SFR 16 03 -38.1           ~ 604 0
12 V* HO Lup Or* 16 07 00.603672 -39 02 19.49316   13.94 13.17 13.03   M1e 62 0
13 THA 15-27 Y*O 16 08 28.43136 -39 05 32.4312   17.03 15.46 14.00 12.35 M4 26 0
14 Lupus 3 SFR 16 09.6 -39 03           ~ 299 0
15 THA 15-36 TT* 16 09 42.565776 -39 19 41.09520   15.30 13.89 13.57 11.68 ~ 27 0
16 THA 15-38 TT* 16 09 57.0796720248 -38 59 48.025255020   15.35 13.71 13.49 11.96 ~ 24 0
17 WSB 18 TT* 16 24 59.74128 -24 56 00.8340   18.9   15.71 13.78 M2.5-M4.5 29 0
18 IRAS 16220-2452 TT* 16 25 02.115744 -24 59 32.40528       14.64 13.12 M3-M5.5 39 0
19 Haro 1-5 TT* 16 26 18.413736 -25 20 55.87404           ~ 19 0
20 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3334 1
21 IRAS 18269+0116 Y*O 18 29 31.9758302760 +01 18 42.616775520           K6.5 37 0

To bookmark this query, right click on this link: simbad:objects in 1997A&A...321..220B and select 'bookmark this link' or equivalent in the popup menu


2022.05.22-23:02:03

© Université de Strasbourg/CNRS

    • Contact