2012A&A...542A.105L


Query : 2012A&A...542A.105L

2012A&A...542A.105L - Astronomy and Astrophysics, volume 542A, 105-105 (2012/6-1)

New ultracool subdwarfs identified in large-scale surveys using virtual observatory tools. I. UKIDSS LAS DR5 vs. SDSS DR7.

LODIEU N., ESPINOZA CONTRERAS M., ZAPATERO OSORIO M.R., SOLANO E., ABERASTURI M. and MARTIN E.L.

Abstract (from CDS):

The aim of the project is to improve our knowledge of the low-mass and low-metallicity population to investigate the influence of metallicity on the stellar (and substellar) mass function. We present the results of a photometric and proper motion search aimed at discovering ultracool subdwarfs in large-scale surveys. We employed and combined the Fifth Data Release (DR5) of the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) and the Sloan Digital Sky Survey (SDSS) Data Release 7 complemented with ancillary data from the Two Micron All-Sky Survey (2MASS), the DEep Near-Infrared Survey (DENIS) and the SuperCOSMOS Sky Surveys (SSS). The SDSS DR7 vs. UKIDSS LAS DR5 search returned a total of 32 ultracool subdwarf candidates, only two of which are recognised as a subdwarf in the literature. Twenty-seven candidates, including the two known ones, were followed-up spectroscopically in the optical between 600 and 1000nm, thus covering strong spectral features indicative of low metallicity (e.g., CaH), 21 with the Very Large Telescope, one with the Nordic Optical Telescope, and five were extracted from the Sloan spectroscopic database to assess (or refute) their low-metal content. We confirm 20 candidates as subdwarfs, extreme subdwarfs, or ultra-subdwarfs with spectral types later than M5; this represents a success rate of ≥60%. Among those 20 new subdwarfs, we identify two early-L subdwarfs that are very likely located within 100pc, which we propose as templates for future searches because they are the first examples of their subclass. Another seven sources are solar-metallicity M dwarfs with spectral types between M4 and M7 without Hα emission, suggesting that they are old M dwarfs. The remaining five candidates do not have spectroscopic follow-up yet; only one remains as a bona-fide ultracool subdwarf after revision of their proper motions. We assigned spectral types based on the current classification schemes and, when possible, we measured their radial velocities. Using the limited number of subdwarfs with trigonometric parallaxes, we estimated distances ranging from ∼95 to ∼600pc for the new subdwarfs. We provide mid-infrared photometry extracted from the WISE satellite databases for two subdwarfs and discuss their colours. Finally, we estimate a lower limit of the surface density of ultracool subdwarfs about 5000-5700 times lower than that of solar-metallicity late-M dwarfs.

Abstract Copyright:

Journal keyword(s): subdwarfs - techniques: photometric - techniques: spectroscopic - infrared: stars - surveys - virtual observatory tools

Errata: erratum vol. 597, art. C3 (2017)

Simbad objects: 48

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Number of rows : 48
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 LP 645-78 PM* 00 25 51.2094370930 -07 48 07.975884728   20.6       sdM6 19 0
2 SDSS J004539.96+135032.6 * 00 45 39.965 +13 50 32.65           sdM7.5 1 0
3 LP 350-34 PM* 00 55 44.2810355629 +25 06 23.579276567   20.6   17.8   sdM6 17 0
4 SDSS J012830.88+134507.3 * 01 28 30.905 +13 45 08.11           ~ 1 0
5 LP 468-277 LM* 01 33 46.2422497028 +13 28 22.325140613   21.0   18.7   esdM6.5 7 0
6 SDSS J015034.33+142002.3 PM* 01 50 34.3360937592 +14 20 02.296598496           sdM8.0 1 0
7 2MASS J02053376+1238242 LM* 02 05 33.7496317656 +12 38 24.032758560           sdM8.0 6 0
8 SDSS J023557.61+010800.5 LM* 02 35 57.6125733960 +01 08 00.772677888           esdM7.0 5 0
9 ULAS J033350.84+001406.1 LM* 03 33 50.7462270574 +00 14 06.208902954           M7.6V 5 0
10 LSR J0822+1700 LM* 08 22 33.7512747281 +17 00 18.928058113       18.7   usdM7.5 16 0
11 LP 258-28 LM* 08 30 51.6486798422 +36 12 56.809731850   19.7   16.6   esdM6 16 0
12 SDSS J083525.40-000940.4 * 08 35 25.409 -00 09 40.49           ~ 1 0
13 SDSS J084153.89+020615.0 ? 08 41 53.892 +02 06 16.15           ~ 1 0
14 LP 545-45 LM* 08 43 58.4562364477 +06 00 39.410772766   19.7 18.49 17.1   esdM5.5 23 0
15 LP 666-9 LM* 08 53 36.1604798120 -03 29 32.197505547     18.959 16.781 14.487 M9Ve 237 0
16 SDSS J085500.12+000204.1 * 08 55 00.123 +00 02 04.03           sdM5.7 1 0
17 LP 486-42 LM* 09 03 08.0511969973 +08 42 43.737487790   18.8   16.8   esdM5.5 13 0
18 SDSS J093502.09+080551.8 * 09 35 02.099 +08 05 51.82           ~ 1 0
19 SDSS J095133.35+070208.9 * 09 51 33.342 +07 02 09.18           ~ 1 0
20 SDSS J100126.29-013426.5 * 10 01 26.294 -01 34 26.57           sdM5.0 1 0
21 SDSS J100743.96-022830.0 ? 10 07 43.964 -02 28 30.02           ~ 1 0
22 SSSPM J1013-1356 LM* 10 13 07.3464466893 -13 56 21.261502194       18.73 16.01 sdM9.5 35 0
23 SDSS J101613.88+011311.3 ? 10 16 13.889 +01 13 11.38           ~ 1 0
24 SDSS J115826.62+044746.8 * 11 58 26.625 +04 47 45.85           sdM9.5 3 0
25 SDSS J120214.61+073113.7 LM* 12 02 14.6076511409 +07 31 14.782370432           M4 2 0
26 SDSS J121508.36+040200.5 PM* 12 15 08.3553561816 +04 02 00.899419632           sdM7.0 1 0
27 SDSS J122145.28+080404.3 * 12 21 45.332 +08 04 03.80           ~ 1 0
28 2MASS J12365942-0021578 LM* 12 36 59.4247530638 -00 21 58.387624427           M4V 4 0
29 SDSS J124234.62+143306.2 LM* 12 42 34.6811593144 +14 33 06.842367149           sdM5.0 1 0
30 ULAS J124425.75+102439.3 PM* 12 44 25.9690664151 +10 24 43.179211214           sdL0.5 5 0
31 SDSS J124621.89+044309.8 * 12 46 21.862 +04 43 09.17           sdM5.0 1 0
32 2MASS J12563590-0019450 LM* 12 56 35.9013886771 -00 19 45.274058039           M3V 5 0
33 2MASS J12563716-0224522 BD* 12 56 37.1377931858 -02 24 52.266257764           esdL3.5 34 0
34 SDSS J131705.65+091016.9 LM* 13 17 05.6748965645 +09 10 18.254530117           esdM7.0 3 0
35 SDSS J141806.70+000035.5 * 14 18 06.706 +00 00 35.50           sdM6.5 1 0
36 LSPM J1425+7102 LM* 14 25 05.0213634857 +71 02 09.686761796   20.8   18.61 16.21 sdM8 29 0
37 LP 440-52 LM* 14 39 00.3086540071 +18 39 38.710151529   19.6 18.39 17.3 14.64 sdM7 60 0
38 LSPM J1454+1235 PM* 14 54 41.4491893126 +12 35 57.739247183   21.6   19.1   esdM5.5 2 0
39 SDSS J151211.63+064251.2 ? 15 12 11.639 +06 42 51.29           ~ 1 0
40 SDSS J154331.92+024537.8 ? 15 43 31.925 +02 45 37.84           ~ 1 0
41 SDSS J154450.59+051613.6 * 15 44 50.597 +05 16 13.59           ~ 1 0
42 SDSS J154855.74+080508.2 * 15 48 55.752 +08 05 08.30           ~ 1 0
43 LSPM J2036+5100 LM* 20 36 21.6139608935 +51 00 04.695268791       17.46 15.26 sdM7.5 24 1
44 LP 758-60 PM* 21 55 47.9570859391 -11 21 42.774681998   19.4 17.40     esdM5 24 0
45 BD+17 4708 SB* 22 11 31.3756832854 +18 05 34.177983548 9.73 9.91 9.46 9.03 8.70 sdF8 552 0
46 USNO-B1.0 0908-00565035 PM* 23 33 50.2586208936 +00 53 42.652794444       20.4   ~ 1 0
47 2MASS J23335840+0050119 LM* 23 33 58.4084596560 +00 50 11.893562844           M9V 12 0
48 SDSS J233359.38+004935.1 * 23 33 59.416 +00 49 34.94           sdM6.0 1 0

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2022.05.28-08:43:11

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