J/MNRAS/313/43 OB association members in ACT+TRC Catalogs (Hoogerwerf, 2000)
OB association members in the ACT and TRC catalogues.
Hoogerwerf R.
<Mon. Not. R. Astron. Soc. 313, 43 (2000)>
=2000MNRAS.313...43H 2000MNRAS.313...43H
ADC_Keywords: Associations, stellar ; Stars, OB
Keywords: astrometry - stars: kinematics -
open clusters and associations: general -
open clusters and associations: individual: Cep OB6, Per OB3, Sco OB2
Abstract:
The Hipparcos Catalogue (Cat. I/239) contains members of nearby OB
associations brighter than 12th magnitude in V. However, membership
lists are complete only to magnitude V=7.3. In this paper we discuss
whether proper motions listed in the `Astrographic Catalogue+Tycho'
reference catalogue (ACT, Cat. I/246) and the Tycho Reference
Catalogue (TRC, Cat. I/250), which are complete to V∼10.5mag, can be
used to find additional association members. Proper motions in the
ACT/TRC have an average accuracy of ∼3mas/yr. We search for ACT/TRC
stars which have proper motions consistent with the spatial velocity
of the Hipparcos members of the nearby OB associations already
identified by de Zeeuw et al. (1999, Cat. J/AJ/117/354). These stars
are first selected using a convergent-point method, and then subjected
to further constraints on the proper-motion distribution, magnitude
and colour to narrow down the final number of candidate members. Monte
Carlo simulations show that the proper-motion distribution, magnitude,
and colour constraints remove ∼97% of the field stars, while at the
same time retain more than 90% of the cluster stars. The procedure has
been applied to five nearby associations: the three subgroups of Sco
OB2, plus Per OB3 and Cep OB6. In all cases except Cep OB6, we find
evidence for new association members fainter than the completeness
limit of the Hipparcos Catalogue. However, narrow-band photometry
and/or radial velocities are needed to pinpoint the cluster members,
and to study their physical characteristics.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
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22 30 +58.0 Cep OB6 = Ass Cep OB 6-
16 14 -24.4 Sco OB2 = Ass Sco OB 2-
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 30 3282 Membership list
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/246 : The ACT Reference Catalog (Urban+ 1997)
I/250 : The Tycho Reference Catalogue (Hog+ 1998)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
V/80 : Low-Mass Stars' Membership in Alpha Persei Cluster (Prosser 1992)
J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Ass Association from which the star is member (1)
11- 14 I4 ---- TYC1 First Tycho-identifier (Cat. I/250)
16- 19 I4 ---- TYC2 Second Tycho-identifier (Cat. I/250)
21 I1 ---- TYC3 Third Tycho-identifier (Cat. I/250)
24 A1 ---- m1 [H] Membership flag (2)
26 A1 ---- m2 [A] Membership flag (2)
28 A1 ---- m3 [T] Membership flag (2)
30 A1 ---- m4 [P] Membership flag (2)
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Note (1): Associations names:
Sco OB2_2 = Upper Scorpius
Sco OB2_3 = Upper Centaurus Lupus
Sco OB2_4 = Lower Centaurus Crux
Per OB3 = α Persei
Cep OB6 = Cep OB6
Note (2): The following flags are used:
H = Member of association selected by de Zeeuw et al.
(1999, Cat. J/AJ/117/354) based on Hipparcos data
A = Member of association based on ACT data (this article)
T = Member of association based on TRC data (this article)
P = Member of association selected by Prosser (1992, Cat. V/80)
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Acknowledgements:
Ronnie Hoogerwerf
(End) Patricia Bauer [CDS] 04-May-2000