2015A&A...574A..96S


Query : 2015A&A...574A..96S

2015A&A...574A..96S - Astronomy and Astrophysics, volume 574A, 96-96 (2015/2-1)

An ancient F-type subdwarf from the halo crossing the Galactic plane.

SCHOLZ R.-D., HEBER U., HEUSER C., ZIEGERER E., GEIER S. and NIEDERHOFER F.

Abstract (from CDS):

We selected the bluest object, WISE J0725-2351, from Luhman's new high proper motion (HPM) survey based on observations with the Wide-field Infrared Survey Explorer (WISE) for spectroscopic follow-up observations. Our aim was to unravel the nature of this relatively bright (V∼12, J∼11) HPM star (µ=267mas/yr). We obtained low- and medium-resolution spectra with the European Southern Observatory (ESO) New Technology Telescope (NTT)/EFOSC2 and Very Large Telescope (VLT)/X-Shooter instruments, investigated the radial velocity and performed a quantitative spectral analysis that allowed us to determine physical parameters. The fit of the spectral energy distribution based on the available photometry to low-metallicity model spectra and the similarity of our target to a metal-poor benchmark star (HD 84937) allowed us to estimate the distance and space velocity. As in the case of HD 84937, we classified WISE J0725-2351 as sdF5: or a metal-poor turnoff star with [Fe/H]=-2.0±0.2, Teff=6250±100K, logg=4.0±0.2, and a possible age of about 12Gyr. At an estimated distance of more than 400pc, its proper motion translates to a tangential velocity of more than 500km/s. Together with its constant (on timescales of hours, days, and months) and large radial velocity (about +240km/s), the resulting Galactic restframe velocity is about 460km/s, implying a bound retrograde orbit for this extreme halo object that currently crosses the Galactic plane at high speed.

Abstract Copyright:

Journal keyword(s): proper motions - stars: distances - stars: kinematics and dynamics - stars: Population II - subdwarfs - white dwarfs

Simbad objects: 19

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Number of rows : 19
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 224927 ** 00 01 49.3993392981 -25 47 54.712350761   9.28 8.96     A9V 49 0
2 * mu. Cas SB* 01 08 16.39470 +54 55 13.2264 5.93 5.86 5.17 4.55 4.13 G5Vb 552 1
3 HD 19445 PM* 03 08 25.5883873084 +26 19 51.400965175 8.29 8.52 8.06 7.60 7.27 G2VFe-3 749 0
4 L 879-6 A PM* 04 25 38.3724758592 -06 52 36.991839307   15.6       M3.0VIJ 13 0
5 HD 33793 PM* 05 11 40.5893175460 -45 01 06.353955874 11.624 10.433 8.853 7.9 6.899 M1VIp 299 0
6 UCAC3 133-60515 PM* 07 25 43.9209656116 -23 51 17.027563740   12.48 12.06 11.98   sdF5.0: 7 0
7 CD-23 5447 * 07 25 44.4840641243 -23 50 54.283978234   11.52 11.68 11.54   ~ 2 0
8 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1795 0
9 L 750-42 LM* 09 43 46.1635512324 -17 47 06.289079555   14.8 13.167 12.693   sdM3 34 0
10 HD 84937 PM* 09 48 56.09801 +13 44 39.3237 8.49 8.68 8.32 7.97 7.70 F8Vm-5 741 0
11 * alf Leo PM* 10 08 22.31099 +11 58 01.9516 0.88 1.24 1.40 1.37 1.47 B8IVn 819 1
12 HD 122563 Pe* 14 02 31.8456299772 +09 41 09.942736952 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 777 0
13 SSSPM J1444-2019 PM* 14 44 20.67432 -20 19 22.2708       18.57 14.97 M9.0VI: 25 0
14 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 879 0
15 L 696-92 LM* 15 43 18.3277723755 -20 15 32.908027529   14.72 13.086 12.782   M2.0VI 27 0
16 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12383 0
17 HD 161817 HB* 17 46 40.6294905277 +25 44 56.936928236 7.23 7.13 6.97     sdA2 262 0
18 * alf Aql dS* 19 50 46.99855 +08 52 05.9563 1.07 0.98 0.76 0.62 0.49 A7Vn 835 0
19 CD-24 17814 PM* 23 43 13.6468552201 -24 09 52.162819755   13.47 12.06 11.84   K4 30 0

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2021.09.22-19:52:48

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