J/MNRAS/453/2220 Early-type Sco-Cen members with literature RVs (Murphy+, 2015)
New members of the TW Hydrae Association and two accreting M-dwarfs in
Scorpius-Centaurus.
Murphy S.J., Lawson W.A., Bento J.
<Mon. Not. R. Astron. Soc., 453, 2220-2232 (2015)>
=2015MNRAS.453.2220M 2015MNRAS.453.2220M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Radial velocities ;
Proper motions ; Parallaxes, trigonometric ; Space velocities
Keywords: stars: formation - stars: low-mass - stars: pre-main sequence -
open clusters and associations: individual: TW Hydrae
Abstract:
We report the serendipitous discovery of several young mid-M stars
found during a search for new members of the 30-40Myr-old Octans
Association. Only one of the stars may be considered a possible
Octans(-Near) member. However, two stars have proper motions,
kinematic distances, radial velocities, photometry and LII
λ6708 measurements consistent with membership in the
8-10Myr-old TW Hydrae Association. Another may be an outlying member
of TW Hydrae but has a velocity similar to that predicted by
membership in Octans. We also identify two new lithium-rich members of
the neighbouring Scorpius-Centaurus OB Association (Sco-Cen). Both
exhibit large 12 and 22µm excesses and strong, variable Hα
emission which we attribute to accretion from circumstellar discs.
Such stars are thought to be incredibly rare at the ∼16Myr median
age of Sco-Cen and they join only one other confirmed M-type and three
higher mass accretors outside of Upper Scorpius. The serendipitous
discovery of two accreting stars hosting large quantities of
circumstellar material may be indicative of a sizeable age spread in
Sco-Cen, or further evidence that disc dispersal and planet formation
time-scales are longer around lower mass stars. To aid future studies
of Sco-Cen, we also provide a newly compiled catalogue of 305
early-type Hipparcos members with spectroscopic radial
velocities sourced from the literature.
Description:
The aim of our photometric and proper motion survey was to identify
new Octans members on the cool side of its lithium depletion boundary
(LDB) in order to better refine the age of the association. Candidates
for spectroscopy were selected from the SPM4 proper motion catalogue
(Girard et al., 2011AJ....142...15G 2011AJ....142...15G, Cat. I/320).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 165 305 *Early-type Sco-Cen members with literature RVs
--------------------------------------------------------------------------------
Note on tablea1.dat: New Hipparcos astrometry, literature radial velocities and
re-calculated UVW space motions and XYZ positions of 305 Sco-Cen members
proposed by de Zeeuw et al. (1999, Cat. J/AJ/117/354)
--------------------------------------------------------------------------------
See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
I/320 : SPM 4.0 Catalog (Girard+, 2011)
J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999)
III/252 : Pulkovo radial velocities for 35493 HIP stars (Gontcharov 2006)
III/254 : 2nd Cat. of RV with Astrometric Data (Kharchenko+, 2007)
J/ApJ/738/122 : ScoCen debris disks Around F- and G-type stars (Chen+, 2011)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- HIP [50083/83693] HIP number
7- 16 F10.6 deg RAdeg Right ascension (J2000)
18- 27 F10.6 deg DEdeg Declination (J2000)
29- 37 F9.5 deg GLON Galactic longitude
39- 47 F9.6 deg GLAT Galactic latitude
49- 53 F5.2 mas Plx Trigonometric parallax
55- 58 F4.2 mas e_Plx rms uncertainty on Plx
60- 65 F6.2 mas/yr pmRA Proper motion mu_alpha.cos(delta)
67- 70 F4.2 mas/yr e_pmRA rms uncertainty on pmRA
72- 77 F6.2 mas/yr pmDE Proper motion mu_delta
79- 82 F4.2 mas/yr e_pmDE rms uncertainty on pmDE
84- 89 F6.2 --- pmGLON Proper motion in Galactic Longitude
91- 96 F6.2 --- pmGLAT Proper motion in Galactic Latitude
98-102 F5.1 km/s RV Radial velocity
104-106 F3.1 km/s e_RV rms uncertainty on RV
108-113 A6 --- r_RV Reference for RV (1)
115-119 F5.1 --- X Heliocentric X position (+ towards GC)
121-126 F6.1 --- Y Heliocentric Y position
128-132 F5.1 --- Z Heliocentric Z position
134-138 F5.1 km/s Uvel Heliocentric U velocity component
140-143 F4.1 km/s e_Uvel rms uncertainty on UVel
145-149 F5.1 km/s Vvel Heliocentric V velocity component
151-154 F4.1 km/s e_Vvel rms uncertainty on VVel
156-160 F5.1 km/s Wvel Heliocentric W velocity component
162-165 F4.1 km/s e_Wvel rms uncertainty on WVel
--------------------------------------------------------------------------------
Note (1): Radial velocity references as follows:
chen = Chen et al. 2011, Cat. J/ApJ/738/122
crvad2 = Kharchenko et al., 2007AN....328..889K 2007AN....328..889K, Cat. III/254
pcrv = Gontcharov, 2006AstL...32..759G 2006AstL...32..759G, Cat. III/252
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Mar-2016