Issue |
A&A
Volume 387, Number 1, May III 2002
|
|
---|---|---|
Page(s) | 117 - 128 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20020418 | |
Published online | 15 May 2002 |
Study of the Per OB2 star forming complex
II. Structure and kinematics
1
Institute of Astronomy of the Russian Acad. Sci., 48 Pyatnitskaya Str., Moscow 109017, Russia e-mail: abelikov@inasan.rssi.ru, piskunov@inasan.rssi.ru
2
Main Astronomical Observatory, 27 Academica Zabolotnogo Str., 03680 Kiev, Ukraine e-mail: nkhar@mao.kiev.ua
3
Astronomisches Rechen-Institut, Mönchhofstraße 12-14, 69120 Heidelberg, Germany e-mail: elena@ari.uni-heidelberg.de
4
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
Corresponding author: R. D. Scholz, rdscholz@aip.de
Received:
3
October
2001
Accepted:
4
March
2002
The study of a sky area with a 20 degree diameter
centered on the nearby association Per OB2 has been carried out on
the basis of the “Compiled Catalogue of Astronomical Data in the
Per OB2 Field” presented in a previous paper. The catalogue contains
about stars with accurate proper motions in the Hipparcos
system as well as magnitudes supplemented with spectral classes and
other relevant data. We applied the reduced proper motion technique
to estimate individual distances for almost all catalogue stars. The
distributions of reddening and interstellar extinction were
determined on the basis of the spectral classification of stars in
the area. Proper motions were corrected for differential rotation of
the Galactic disk and parallactic motion effects and used for the evaluation
of association membership. The analysis of a uniform subset
of main sequence (MS) stars earlier than A7 – which is complete within
500 pc – has clearly revealed the association as an area of enhanced
density with an angular size of about
. In comparison to the
previous results on Per OB2, we show that the presently determined
area extends the association from its classical position towards the
California nebula and the Auriga dark cloud. There are 1025 MS proper
motion members residing in this region. The distance to the
association centre derived from a kinematic calibration is found to
be about 300 pc i.e., in perfect agreement with the Hipparcos data.
The shape of the association is almost spherical, and its diameter
found from stellar counts is about 40 pc. An examination of internal
systematic motions from proper motion data has shown that there is
no evidence of an expansion or a rotation of the association around
the line of sight. The average tangential and spatial velocity
vectors of Per OB2 with respect to the LSR are determined as
km s-1 and
km s-1.
Key words: stars: distances / ISM: dust, extinction / stars: Hertzsprung-Russell (HR) and C-M diagrams / Galaxy: open clusters and associations: individual: Per OB2
© ESO, 2002
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