J/AJ/143/80 Low-mass stars of beta Pic and AB Dor groups (Schlieder+, 2012)
Cool young stars in the northern hemisphere: β Pictoris and AB Doradus
moving group candidates.
Schlieder J.E., Lepine S., Simon M.
<Astron. J., 143, 80 (2012)>
=2012AJ....143...80S 2012AJ....143...80S
ADC_Keywords: Associations, stellar; Stars, pre-main sequence ;
Photometry, infrared ; Proper motions ; Radial velocities
Keywords: open clusters and associations: individual
(Beta Pictoris, AB Doradus) - stars: kinematics and dynamics -
stars: pre-main sequence
Abstract:
As part of our continuing effort to identify new, low-mass members of
nearby, young moving groups (NYMGs), we present a list of young,
low-mass candidates in the northern hemisphere. We used our proven
proper-motion selection procedure and ROSAT X-ray and GALEX-UV
activity indicators to identify 204 young stars as candidate members
of the β Pictoris and AB Doradus NYMGs. Definitive membership
assignment of a given candidate will require a measurement of its
radial velocity and distance. We present a simple system of indices to
characterize the young candidates and help prioritize follow-up
observations. New group members identified in this candidate list will
be high priority targets for (1) exoplanet direct imaging searches,
(2) the study of post-T-Tauri astrophysics, (3) understanding recent
local star formation, and (4) the study of local galactic kinematics.
Information available now allows us to identify eight likely new
members in the list. Two of these, a late-K and an early-M dwarf, we
find to be likely members of the β Pic group. The other six stars are
likely members of the AB Dor moving group. These include an M dwarf
triple system, and three very cool objects that may be young brown
dwarfs, making them the lowest-mass, isolated objects proposed in the
AB Dor moving group to date.
Description:
We search in proper-motion catalogs (Tycho-2, 2005, Cat. I/259;
LSPM-North, 2005, Cat. I/298; the SUPERBLINK all-sky proper motion
catalog, Lepine et al., 2012; in prep, SUPERBLINK is the smaller
proper-motion counterpart of the LSPM-North catalog) candidates of
the β Pictoris moving group and AB Doradus moving group. Then we
perform a positional cross-correlation of the candidates with the
ROSAT All-Sky Survey Bright Source (Voges et al., 1999, Cat. IX/10)
and the ROSAT Faint Source catalogs (Voges et al., 2000, Cat. IX/29).
Finally we cross-correlate our candidate list with the sixth data
release of the GALEX All-Sky Imaging survey (a webtool for accessing
GALEX data available at http://galex.stsci.edu/galexview/). This
analysis reduced our sample to 204 probable young candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 139 204 Northern Probable Young Candidate (PYC) list
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See also:
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/298 : LSPM-North Catalog (Lepine+ 2005)
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
J/AJ/140/119 : βPic and AB Dor moving groups members (Schlieder+, 2010)
J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006)
J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004)
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [PYC]
5- 16 A12 --- PYC Probable young candidate identifier
<[SLS2012] PYC JHHMMm+DDMMW> in Simbad (1)
18- 22 I5 --- HIP ? Hipparcos identifier if available
24- 34 A11 --- TYC Tycho2 identifier if available (Cat. I/259)
36- 45 F10.6 deg RAdeg Right Ascension (ICRS, epoch=J2000)
47- 55 F9.6 deg DEdeg Declination (ICRS, epoch=J2000)
57- 60 F4.1 mag Vmag [9.2/20.6] The V band magnitude (2)
62- 65 F4.1 mag Jmag [6.6/11.9] The 2MASS J band magnitude
67- 70 F4.1 mag Hmag [6.1/11.4] The 2MASS H band magnitude
72- 75 F4.1 mag Ksmag [6/11.3] The 2MASS Ks band magnitude
77- 82 F6.1 mas/yr pmRA Proper motion in Right Ascension (3)
84- 89 F6.1 mas/yr pmDE Proper motion in Declination (3)
91- 94 F4.1 pc Dkin [17/70] Kinematic distance (4)
96- 99 F4.1 pc e_Dkin Uncertainty in Dkin
101-106 F6.2 km/s RVp [-29.7/19.7] Predicted radial velocity (5)
108-111 F4.2 km/s e_RVp Uncertainty in RVp (6)
113-117 F5.2 [-] log(X) Logarithm of X-ray to Ks band flux ratio
119-123 F5.2 [-] log(N) Log of GALEX NUV to Ks band flux ratio
125-129 F5.2 [-] log(F) Log of GALEX FUV to Ks band flux ratio
131-133 A3 --- A [01] PYC status from activity index (7)
135 I1 --- C [0/1]? PYC status from color index (8)
137 I1 --- P [1/4] The priority index (4=most promising
youth candidate) (9)
139 I1 --- Grp [1/2] Moving group candidacy:
1=β Pic (BPMG), 2=AB Dor (ABDMG)
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Note (1): Based on the star's coordinates in the ICRS epoch 2000.0 system.
The final letter (N, S, E, W) is optional and distinguishes pairs of
stars that would otherwise have the same coordinates. The choice
depends on the orientation of the pair. If the separation in
declination is larger, the stars are appended N and S. If the
separation in right ascension is larger, the pair is given E and W.
Note (2): If the star is in the Hipparcos (Cat. I/239) or Tycho-2 (Cat. I/259)
catalog the V mags from those sources are used. If the star is missing
from those catalogs the V mag is a combination of the USNO-B1.0
(Monet et al., 2003, Cat. I/284) BJ, RF, and IF photographic
magnitudes following the conventions of the LSPM-North catalog
(Lepine & Shara, 2005, Cat. I/298).
Note (3): From the Hipparcos (Cat. I/239) and Tycho-2 (Cat. I/259) catalogs if
the candidate has a counterpart, otherwise the LSPM-North catalog
(Lepine & Shara, 2005, Cat. I/298)/SUPERBLINK (Lepine et al.,
2012, in prep.) derived proper motions are used.
Note (4): Derived from the proper motion assuming moving group membership.
See Lepine & Simon (2009AJ....137.3632L 2009AJ....137.3632L), equations (5)-(7).
Note (5): Calculated assuming group membership.
See Lepine & Simon (2009AJ....137.3632L 2009AJ....137.3632L) and
Schlieder et al. (2010, Cat. J/AJ/140/119).
Note (6): Includes the intrinsic spread in β Pictoris moving group or
AB Doradus moving group UVW velocities quoted in Section 2.
Note (7): The activity index is a three digit binary number where each digit
represents whether a youth diagnostic is positive (1) or not (0).
* first digit: from X-ray flux ratio: 1 indicates that the ratio
is at or above the PYC cut, and 0 means that the ratio is either
below the cut or X-ray flux is not detected.
* second digit: near-UV flux ratio
* third digit: far-UV flux ratio.
Note (8): status from color index (V-Ks) (see Section 4.4 for more details):
0 = Probable young candidates (PYC) with ambiguous youth ((V-Ks)≥5);
1 = Probable young candidates (PYC) with reliable youth ((V-Ks)≤5).
Note (9): The observing priority of a probable young candidate can be
quickly determined by summing the digits of the activity and color
index. This leads to a one digit priority index, which ranges between
1 and 4. The most promising candidates, with strong, reliable
indication of youth, have priority index=4.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 16-May-2013