2012A&A...546A..63V


Query : 2012A&A...546A..63V

2012A&A...546A..63V - Astronomy and Astrophysics, volume 546A, 63-63 (2012/10-1)

Astrometric confirmation of young low-mass binaries and multiple systems in the Chamaeleon star-forming regions.

VOGT N., SCHMIDT T.O.B., NEUHAEUSER R., BEDALOV A., ROELL T., SEIFAHRT A. and MUGRAUER M.

Abstract (from CDS):

The star-forming regions in Chamaeleon (Cha) are one of the nearest (distance ∼165pc) and youngest (age ∼2Myr) conglomerates of recently formed stars and the ideal target for population studies of star formation. We investigate a total of 16 Cha targets that have been suggested, but not confirmed, to be binaries or multiple systems in previous literature. We used the adaptive optics instrument Naos-Conica (NACO) at the Very Large Telescope Unit Telescope (UT) 4/YEPUN of the Paranal Observatory, at 2-5 different epochs, in order to obtain relative and absolute astrometric measurements, as well as differential photometry in the J, H, and K band. On the basis of known proper motions and these observations, we analyse the astrometric results in our proper motion diagram (PMD: angular separation/position angle versus time), to eliminate possible (non-moving) background stars, establish co-moving binaries and multiples, and search for curvature as indications for orbital motion. All previously suggested close components are co-moving and no background stars are found. The angular separations range between 0.07 and 9-arcsec, corresponding to projected distances between the components of 6-845AU. Thirteen stars are at least binaries and the remaining three (RX J0919.4-7738, RX J0952.7-7933, VW Cha) are confirmed high-order multiple systems with up to four components. In 13 cases, we found significant slopes in the PMDs, which are compatible with orbital motion whose periods (estimated from the observed gradients in the position angles) range from 60 to 550 years. However, in only four cases there are indications of a curved orbit, the ultimate proof of a gravitational bond. A statistical study based on the 2MASS catalogue confirms the high probability of all 16 stellar systems being gravitationally bound. Most of the secondary components are well above the mass limit of hydrogen burning stars (0.08 M), and have masses twice as high as this value or more. Massive primary components appear to avoid the simultaneous formation of equal-mass secondary components, while extremely low-mass secondary components are hard to find for both high and low mass primaries owing to the much higher dynamic range and the faintness of the secondaries.

Abstract Copyright:

Journal keyword(s): stars: imaging - stars: pre-main sequence - binaries: general - binaries: close - astrometry - infrared: stars

Simbad objects: 25

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Number of rows : 25
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 HD 8415A PM* 01 22 46.8251628792 -30 37 41.659200696   9.34 8.92 9.51   F3V 16 0
2 RX J0915.4-7608 Ro* 09 15 29.1294168312 -76 08 47.129815104     12.142   10.452 K7 21 0
3 HD 81485B SB* 09 19 23.9788595160 -77 38 45.104008632   10.43 9.569     K0IVe 19 0
4 HD 81485A TT* 09 19 24.6525107640 -77 38 36.351469968   9.02 8.33     G7V 30 0
5 HD 81485 ** 09 19 24.66139 -77 38 36.3382     8.051   7.271 G7V+K0IVe 43 0
6 [K2001c] 17 LM* 09 34 55.8994070808 -78 04 19.246056996     13.87     M3 18 0
7 HD 86588 ** 09 53 13.7246814696 -79 33 28.627177500   10.17 9.63     F6V 20 0
8 [K2001c] 27 TT* 10 14 08.07 -76 36 32.8   15.802 14.186     M4 17 0
9 V* SZ Cha Or* 10 58 16.7500775160 -77 17 17.185749900     12.68   10.62 K0e 112 0
10 V* CT Cha Or* 11 04 09.0989256840 -76 27 19.329779664   13.44 13.00   10.89 K7Ve 118 0
11 Ass Cha T 2-21 TT* 11 06 15.3471261840 -77 21 56.720362608   12.58 11.01   9.35 G5Ve 129 0
12 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1070 1
13 V* HK Cha Or* 11 07 42.3364909752 -77 33 59.394350844   21.9 19.8   15.26 ~ 76 0
14 Sz 23 Or* 11 07 58.0951794888 -77 42 41.352365124   15.8 18.04   14.63 M4Ve 59 0
15 V* VW Cha Or* 11 08 01.3974165580 -77 42 28.579297348 13.91 14.04 12.80   10.69 K7+M0 172 0
16 [CCE98] 1-74 TT* 11 09 17.6942588064 -76 27 57.926988648   15.48 13.92   11.72 K4Ve 40 0
17 HD 97300 Ae* 11 09 50.0199904704 -76 36 47.718191232   9.41 9.20   8.82 B9V 164 1
18 V* WX Cha Or* 11 09 58.666944 -77 37 09.03432   14.93 13.85 14.23 12.20 M1+M5 93 0
19 V* WY Cha Or* 11 10 07.0339153464 -76 29 37.674167388   15.29 13.87   11.62 K8Ve 80 1
20 Glass Q Y*O 11 10 37.8987149352 -77 32 39.881630256   16.89 14.97   11.90 K5.5+K7 67 0
21 Sz 41 TT* 11 12 24.3973943352 -76 37 06.181395384   11.2 11.60   10.22 K7+M2.5 92 1
22 Ass Cha T 2-54 TT* 11 12 42.6709132056 -77 22 22.943489160     11.103   9.653 G8+K7 81 2
23 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 747 0
24 HD 132347 ** 14 59 29.23211 -30 42 41.5076           A3mA5-F0 23 0
25 [MR81] HA 17 TT* 19 10 43.3789302408 -36 59 09.345472548   18.1 16.9     ~ 12 0

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2022.08.10-13:23:31

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