J/AJ/117/354 OB associations from Hipparcos (de Zeeuw+, 1999)
A Hipparcos census of the nearby OB associations.
De Zeeuw P.T., Hoogerwerf R., De Bruijne J.H.J., Brown A.G.A., Blaauw A.
<Astron. J. 117, 354 (1999)>
=1999AJ....117..354D 1999AJ....117..354D
ADC_Keywords: Associations, stellar ; Stars, OB
Keywords: stars: early-type - stars: formation - stars: kinematics -
stars: statistics - stars: premain-sequence -
open clusters and associations: general -
open clusters and associations: individual (Gould Belt)
Abstract:
A comprehensive census of the stellar content of the OB associations
within 1 kpc from the Sun is presented, based on Hipparcos positions,
proper motions, and parallaxes. It is a key part of a long-term
project to study the formation, structure, and evolution of nearby
young stellar groups and related star-forming regions. OB associations
are unbound "moving groups", which can be detected kinematically
because of their small internal velocity dispersion. The nearby
associations have a large extent on the sky, which traditionally has
limited astrometric membership determination to bright stars
(V~<6mag), with spectral types earlier than ∼B5. The Hipparcos
measurements allow a major improvement in this situation. Moving
groups are identified in the Hipparcos Catalog by combining de
Bruijne's (1999MNRAS.306..394H 1999MNRAS.306..394H) refurbished convergent point method
with the "Spaghetti method" of Hoogerwerf & Aguilar (1999, MNRAS, in
press). Astrometric members are listed for 12 young stellar groups,
out to a distance of ∼650pc. These are the three subgroups Upper
Scorpius, Upper Centaurus Lupus, and Lower Centaurus Crux of Sco OB2,
as well as Vel OB2, Tr 10, Col 121, Per OB2, α Persei (Per OB3),
Cas-Tau, Lac OB1, Cep OB2, and a new group in Cepheus, designated as
Cep OB6.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablec1.dat 15 1130 Membership list
--------------------------------------------------------------------------------
See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- OBAss [A-L] OB association code (1)
3 A1 --- Type [el] e: early-type, l: late-type
5- 10 I6 --- HIP HIP (Cat. I/239) number
12- 14 I3 % Memb Membership probability
--------------------------------------------------------------------------------
Note (1): associations and statistics of population:
----------------------------------------------------------------------------
Code OB association Ntot O B A F G K M R
----------------------------------------------------------------------------
A Upper Scorpius 120 0 49 34 22 9 4 2 0
B Upper Centaurus Lupus 221 0 66 68 55 25 6 1 0
C Lower Centaurus Crux 180 0 42 55 61 15 6 1 0
D Vel OB2 93 1 81 5 0 3 3 0 0
E Trumpler 10 23 0 22 1 0 0 0 0 0
F Collinder 121 103 2 85 8 1 1 3 3 0
G Per OB2 41 0 17 16 2 2 3 1 0
H α Persei (Per OB3) 79 0 30 33 12 2 2 0 0
I Cas-Tau (OB stars only) 83 0 83
J Lac OB1 96 1 35 46 1 0 8 3 2
K Cep OB2 71 1 53 10 4 0 2 1 0
L Cep OB6 20 0 6 7 1 2 3 0 1
--------------------------------------------------------------------------------
History:
From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 26-Feb-1999