2009A&A...499..729L


Query : 2009A&A...499..729L

2009A&A...499..729L - Astronomy and Astrophysics, volume 499, 729-736 (2009/6-1)

Lucky imaging of M subdwarfs.

LODIEU N., ZAPATERO OSORIO M.R. and MARTIN E.L.

Abstract (from CDS):

The knowledge of the binary properties of metal-poor and solar-metallicity stars can shed light on the potential differences between the formation processes responsible for both types of objects. The aim of the project is to determine the binary properties (separation, mass ratio, frequency of companions) for M subdwarfs, the low-metallicity counterparts of field M dwarfs, and investigate any potential differences between both populations. We have obtained high-resolution imaging in the optical for a sample of 24 early-M subdwarfs and nine extreme subdwarfs with the ``Lucky Imaging'' technique using the AstraLux instrument on the Calar Alto 2.2-m telescope. We are sensitive to companions at separations larger than 0.1 arcsec and differences of ∼2mag at 0.1arcsec and ∼5mag at 1arcsec. We have found no companion around the 24 subdwarfs under study and one close binary out of nine extreme subdwarfs. A second image of LHS182 taken three months later with the same instrument confirms the common proper motion of the binary separated by about 0.7arcsec. Moreover, we do not confirm the common proper motion of the faint source reported by Riaz and collaborators at ∼2arcsec from LHS1074. We derive a binary frequency of 3±3% for M subdwarfs from our sample of 33 objects for separations larger than about five astronomical units. Adding to our sample the additional 28 metal-poor early-M dwarfs observed with the Hubble Space Telescope by Riaz and collaborators, we infer a binary fraction of 3.7±2.6% (with a 1σ confidence limit), significantly lower than the fraction of resolved binary M dwarfs (∼20%) over the same mass and separation ranges. This result suggests a sharp cut-off in the multiplicity fraction from G to M subdwarfs, indicating that the metallicity plays a role at lower masses and/or an environmental effect governing the formation of metal-poor M dwarfs compared to their metallicity counterparts.

Abstract Copyright:

Journal keyword(s): methods: observational - techniques: photometric - Galaxy: halo - stars: binaries: general - stars: low-mass, brown dwarfs - infrared: stars

Simbad objects: 43

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Number of rows : 43
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 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3749 0
2 LP 645-78 PM* 00 25 51.2094370930 -07 48 07.975884728   20.6       sdM6 19 0
3 LSR J0157+5308 PM* 01 57 40.6328942139 +53 08 13.396504212   13.8       sdM3.5 7 0
4 Wolf 110 LM* 02 02 52.1477540612 +05 42 20.954967701   13.69   11.845   d/sdM0 58 0
5 G 4-29 LM* 02 34 12.4531586738 +17 45 50.514094508   16.590 14.911 13.852 12.612 sdM3 29 0
6 G 76-39 LM* 02 52 45.5137961739 +01 55 50.574033985   16.27 14.73 13.5 12.73 esdM2 34 0
7 L 802-6 PM* 02 58 10.2284360866 -12 53 06.002343593   14.40 12.669 12.258   sdM3.0 44 0
8 Ross 585 PM* 03 30 44.8190409266 +34 01 07.190996589   14.0   12.26   sdM0 37 0
9 Ross 578 LM* 03 38 15.6979940371 -11 29 13.505034257   14.67 13.02     d/sdM2 60 0
10 Wolf 1057 LM* 03 42 29.4197307870 +12 31 33.525352939   14.46 12.841 12.466   d/sdM1 41 0
11 LSR J0342+5527 PM* 03 42 53.7334985150 +55 27 30.440989393   16.6   14.9   sdM0.0 6 0
12 G 79-69 ** 03 46 24.579048 +11 43 11.85420   16.39 14.90 14.65   ~ 14 0
13 G 95-59 LM* 03 50 13.88544 +43 25 40.6416       13.34   usdM0 37 0
14 G 7-17 LM* 04 01 36.5894047141 +18 43 39.936895336   17.35       esdM0.5 43 0
15 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4015 0
16 G 86-27 PM* 05 10 31.3980510051 +31 17 35.358129347   15.8   14.3   ~ 13 0
17 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2174 1
18 NAME Trapezium Cluster As* 05 35 16.5 -05 23 14           ~ 1558 1
19 G 99-33 LM* 05 48 00.2059869812 +08 22 14.080603980   15.57   13.4   sdM0.0 21 0
20 LSR J0618+1614 PM* 06 18 52.5231063187 +16 14 56.100221092   16.7   14.5 12.9 sdM2.0 7 0
21 LP 540-16 LM* 06 27 33.3066851296 +06 16 58.842287118   17.3   15.4   esdM1.5 9 0
22 LSR J0705+0506 PM* 07 05 48.7628818144 +05 06 17.120776093   18.4   14.1   sdM4 8 0
23 G 46-40 PM* 09 25 31.0851899102 +00 18 17.681410163   16.61   14.0   sdM0.5 18 0
24 LP 607-65 PM* 09 25 31.2896900903 +00 18 23.571012810   19.0   17.6   ~ 17 0
25 G 176-40 LM* 11 32 45.3367048422 +43 59 42.520011148   16.0   14.1   sdM0.5 24 0
26 Ross 451 LM* 11 40 20.3051170434 +67 15 32.363188342   12.291   11.2   esdM0 62 0
27 G 121-45 PM* 12 02 18.0738047744 +28 35 14.200092334   14.70   12.45   sdM3.5 52 1
28 G 11-35 LM* 12 02 33.6593316712 +08 25 50.730959800   15.58   13.2   sdM2.0 31 0
29 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3265 0
30 G 165-47 LM* 14 06 55.5867880692 +38 36 56.042385139   16.24   13.7   usdM1 43 0
31 LSPM J1755+1648 PM* 17 55 32.7616188669 +16 48 58.898212749   17.0   14.8   sdM3.5 13 0
32 LP 24-219 LM* 18 21 52.9573065588 +77 09 30.023517736   18.0   15.9   usdM3 28 0
33 LP 141-1 LM* 18 45 52.2450125367 +52 27 40.624600956   16.72 14.96 14.67   d/sdM4 44 0
34 LSR J1914+2825A PM* 19 14 05.5011839649 +28 25 52.326516255   17.0   15.4   sdM0.0 4 0
35 G 143-8 LM* 19 46 48.6287456729 +12 04 59.076720142   15.82   13.9   sdM1.0 22 0
36 Wolf 1130 Er* 20 05 02.1950576493 +54 26 03.234326252   11.970 13.883     sdM1 131 0
37 LSPM J2009+5659 PM* 20 09 33.7936415462 +56 59 25.767242385   16.8   14.6   sdM2.0 8 0
38 2MASS J20093416+5659301 * 20 09 34.1753733888 +56 59 30.307454232           ~ 1 0
39 LP 515-3 LM* 20 19 04.5756924481 +12 35 04.034862267   16.5   14.8   usdM0 28 0
40 G 210-19 LM* 20 27 29.0847575225 +35 59 24.806092104   16.39   14.0   sdM1.5 32 0
41 Wolf 1106 LM* 21 07 55.3979731725 +59 43 19.333213671   14.85   13.7   sdM1.5 54 0
42 LSPM J2205+5807 PM* 22 05 32.6471974807 +58 07 25.429842167   17.9   17.5   esdM1.0 4 0
43 G 128-34 LM* 23 08 26.0376705399 +31 40 23.802272530   16.19   13.8   esdM0.5 27 0

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2022.10.01-03:44:14

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