2011ApJ...727....6S


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.21CEST15:43:41

2011ApJ...727....6S - Astrophys. J., 727, 6 (2011/January-3)

Searching for young M dwarfs with GALEX.

SHKOLNIK E.L., LIU M.C., REID I.N., DUPUY T. and WEINBERGER A.J.

Abstract (from CDS):

The census of young moving groups in the solar neighborhood is significantly incomplete in the low-mass regime. We have developed a new selection process to find these missing members based on the Galaxy Evolution Explorer (GALEX) All-Sky Imaging Survey (AIS). For stars with spectral types ≳ K5 (R - J ≳ 1.5) and younger than ~300 Myr, we show that near-UV (NUV) and far-UV (FUV) emission is greatly enhanced above the quiescent photosphere, analogous to the enhanced X-ray emission of young low-mass stars seen by ROSAT but detectable to much larger distances with GALEX. By combining GALEX data with optical (HST Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 deg2 region around the ~10 Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had Hα in emission, which were then followed up at high resolution to search for spectroscopic evidence of youth and to measure their radial velocities. Four objects have low surface gravities, photometric distances and space motions consistent with TWA, but the non-detection of Li indicates that they may be too old to belong to this moving group. One object (M3.5, 93±19 pc) appears to be the first known accreting low-mass member of the ~15 Myr Lower Centaurus Crux OB association. Two objects exhibit all the characteristics of the known TWA members, and thus we designate them as TWA 31 (M4.2, 110±11 pc) and TWA 32 (M6.3, 53 ±5 pc). TWA 31 shows extremely broad (447 km/s) Hα emission, making it the sixth member of TWA found to have ongoing accretion. TWA 32 is resolved into a 0".6 binary in Keck laser guide star adaptive optics imaging. Our search should be sensitive down to spectral types of at least M4-M5 in TWA and thus the small numbers of new member is puzzling. This might indicate TWA has an atypical mass function or that the presence of lithium absorption may be too restrictive a criteria for selecting young low-mass stars.

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: TW Hydrae Association - stars: kinematics and dynamics - stars: low-mass - stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be - ultraviolet: stars

Nomenclature: TWA NN (Nos 31-32) added.

Simbad objects: 55

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Number of rows : 55

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3542 0
2 Wolf 1539 PM* 04 52 05.7323109095 +06 28 35.589503596 14.791 13.568 12.018 10.854 9.334 M2V 125 1
3 * eta Cha * 08 41 19.5144242735 -78 57 48.102318990 5.02 5.351 5.453     B8V 214 0
4 2MASS J10062473-3014439 PM* 10 06 24.7398184064 -30 14 44.243470279           ~ 2 0
5 2MASS J10132142-3542369 * 10 13 21.4356089995 -35 42 37.001729081           ~ 1 0
6 TWA 22 LXB 10 17 26.8983656044 -53 54 26.459439803   15.69 13.96 13.72   M5 70 0
7 2MASS J10305453-4011275 * 10 30 54.5312511443 -40 11 27.562532664           ~ 1 0
8 2MASS J10371046-3505015 PM* 10 37 10.4693430639 -35 05 01.515120753           ~ 1 0
9 2MASS J10395276-3534030 IR 10 39 52.764 -35 34 03.03           ~ 1 0
10 V* CE Ant TT* 10 42 30.1021269333 -33 40 16.226774953   12.21 10.91   9.10 M2Ve 152 1
11 NAME TW Hya Association As* 11 01.9 -34 42           ~ 826 0
12 2MASS J11025372-3145105 * 11 02 53.7284883836 -31 45 10.597711202           ~ 1 0
13 2MASS J11060245-3105083 PM* 11 06 02.4510785576 -31 05 08.324531730           ~ 1 0
14 CD-29 8887 TT* 11 09 13.8074415397 -30 01 40.070212113   12.95 11.119 10.642 8.875 M2Ve 111 0
15 TWA 3B TT* 11 10 27.8410112470 -37 31 52.748874445   14.59 13.70   8.86 M4Ve 49 0
16 TWA 3 ** 11 10 27.894072 -37 31 51.96612   13.53 12.05 11.61 9.29 M4Ve+M4Ve 200 0
17 TWA 3A TT* 11 10 27.9117558304 -37 31 51.529219753   14.04 12.57   9.10 M4Ve 187 0
18 2MASS J11114636-3937347 * 11 11 46.3615996023 -39 37 34.790606498           ~ 1 0
19 2MASS J11115267-4401538 * 11 11 52.6769789750 -44 01 53.835455270           ~ 2 0
20 V* V1215 Cen TT* 11 13 26.2208332352 -45 23 42.719174706     12.478   10.483 K8IVe 68 0
21 2MASS J11181237-3235590 * 11 18 12.3770899566 -32 35 59.119555246           ~ 1 0
22 V* V1217 Cen BY* 11 21 05.4812165874 -38 45 16.521880972   14.04 12.58 12.34 10.515 M1Ve 64 0
23 2MASS J11305355-4628251 IR 11 30 53.5004264787 -46 28 25.086215649           ~ 2 0
24 2MASS J11311482-4826279 * 11 31 14.8287995954 -48 26 28.017619473           ~ 3 0
25 CD-33 7795 TT* 11 31 55.2603055856 -34 36 27.214242128   12.97 11.524 11.150 9.150 M2Ve 176 0
26 TWA 30B LM* 11 32 18.2184758367 -30 18 31.652412622         16.68 M4 33 0
27 TWA 30 Y*O 11 32 18.3109439046 -30 19 51.860228754   15.82 14.20 14.44 11.30 M5V 55 0
28 CD-26 8623B TT* 11 32 41.1729967174 -26 52 09.110626414   16.70 15.22 13.68 11.76 M5.5 66 0
29 CD-26 8623 TT* 11 32 41.2659398509 -26 51 55.961617611   13.69 12.23 11.14 9.637 M3Ve 87 0
30 2MASS J11345651-3640280 * 11 34 56.5087092470 -36 40 28.200811157           ~ 1 0
31 2MASS J11345890-3443115 PM* 11 34 58.9010702836 -34 43 11.622569787           ~ 1 0
32 2MASS J11390806-4532398 IR 11 39 08.064 -45 32 39.81           ~ 1 0
33 CD-32 8298 * 11 45 50.0234621275 -33 02 13.420871493   10.982 10.515     ~ 2 0
34 CD-32 8299 * 11 46 05.1916024591 -32 49 13.489168782   11.33 10.36     ~ 1 0
35 2MASS J11480896-3758094 * 11 48 08.9718733058 -37 58 09.556958247           ~ 1 0
36 TWA 35 LM* 12 00 27.5033934136 -34 05 37.173435048           M4.7 8 0
37 UNSW-V 134 Pu* 12 03 08.0742512175 -38 26 55.521051905         10.23 ~ 2 0
38 TWA 31 PM* 12 07 10.8878369580 -32 30 53.757769890   18.5   16.4   M4.2 22 0
39 TWA 23 TT* 12 07 27.3753633293 -32 47 00.253618251   14.157 12.7     M2.5Ve 56 0
40 NAME Lower Centaurus Crux As* 12 19 -57.1           ~ 361 1
41 2MASS J12190767-4101578 PM* 12 19 07.6735952250 -41 01 57.751383807           ~ 1 0
42 2MASS J12192982-3414245 * 12 19 29.8225331151 -34 14 24.544665954           ~ 1 0
43 2MASS J12202578-4304069 * 12 20 25.7874959381 -43 04 07.062699354           ~ 1 0
44 2MASS J12213327-4140291 IR 12 21 33.274 -41 40 29.12           ~ 1 0
45 2MASS J12240836-3134274 * 12 24 08.3665811904 -31 34 27.527376057           ~ 1 0
46 2MASS J12264374-4147373 IR 12 26 43.7572906755 -41 47 37.334389354           ~ 1 0
47 TWA 32 ** 12 26 51.366576 -33 16 12.54324   17.21 16.00 15.73   M6.3 26 0
48 2MASS J12334357-3251262 PM* 12 33 43.5657182330 -32 51 26.343376490           ~ 2 0
49 V* V1250 Cen TT* 12 34 20.4718890806 -48 15 19.545698484   13.3 12.2   11.80 M3 34 0
50 TWA 16 ** 12 34 56.302608 -45 38 07.63332   14.05 12.58 12.21 10.310 M2.5 52 0
51 V* V1252 Cen TT* 12 35 04.2562814903 -41 36 38.620524379   14.39 13.045   10.506 M2Ve 69 0
52 2MASS J12454360-3704362 * 12 45 43.5956463475 -37 04 36.230042421           ~ 1 0
53 2MASS J12564964-3007373 * 12 56 49.6453866702 -30 07 37.418308232           ~ 1 0
54 NAME beta Pic Moving Group MGr 14 30 -42.0           ~ 573 0
55 V* BR Psc BY* 23 49 12.5251391270 +02 24 04.403044891 11.532 10.427 8.993 8.029 6.946 dM1 284 0

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2020.10.21-15:43:41

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