Proceedings of the
Workshop
"
The Magellanic Clouds and Other Dwarf Galaxies"
of the
Bonn/Bochum-Graduiertenkolleg
Photoelectric UBV Photometry of Galactic Foreground
and LMC Member Stars: A New Database
Th. Schmidt-Kaler1,2, J. Gochermann2,
M.O. Oestreicher1, H.-G. Grothues3,
C. Tappert1, A. Zaum2,
Th. Berghöfer5, and H.R. Brugger4
1Astronomisches Institut der Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
2Optikzentrum NRW, Universitätsstr. 142, D-44799 Bochum,
Germany
3DLR Institut für Planetenerkundung, Rudower Chaussee 5,
D-12849 Berlin, Germany
4Garglasweg 39, CH-7220 Schiers, Switzerland
5Max-Planck-Institut für extraterrestische Physik, Giessenbachstr. 1, D-85740 München, Germany
Received 13th March 1998
Abstract.
In a program of photoelectric UBV photometry of individual stars in
the field of the Large Magellanic Cloud very accurate data have been given
for 1500 and less reliable observations for 379 galactic foreground stars
(Gochermann et al. 1993; Grothues et al. 1997).
Further we have obtained new UBV photometry for 878 LMC member stars
and for 13 stars of uncertain membership (Schmidt-Kaler et al. 1998), following
extensive earlier work with the Bochum 61 cm telescope by Isserstedt
(1975, 1979 and 1982).
1. Statistics and Color-Color-Diagram
Including our new observations now for altogether 2470 luminous LMC stars
(mostly of type O to A) photoelectric UBV data are available.
A histogram for the V magnitude is presented in
Fig. 1.
The completeness limit is 12.8±0.2 mag.
Assuming a mean visual absorption of 0.70±0.06 mag (Oestreicher
& Schmidt-Kaler 1996) the completeness limit for the absorption free
visual magnitude is 12.1±0.2 mag which agrees well with the limits
of 12.0 to 12.3 mag given by these authors.
The color-color-diagram is shown in
Fig. 2.
Many stars are significantly bluer than according to the galactic supergiant
sequences given by Schmidt-Kaler (1982) as already discussed by Gochermann
(1994).
On the other side many stars are obviously strongly reddened as shown by
Oestreicher & Schmidt-Kaler (1996).
Further applications of the data have been given for interstellar reddening
lines by Gochermann (1994) and for calibrations of CCD exposures.
2. A Data Base of LMC Member and Foreground Stars
A new data base has been assembled containing comprehensive informations on
more than 7100 member stars and more than 3200 galactic foreground stars in
the direction to the LMC which are mainly selected by their radial velocities.
Additionally, about 300 stars of uncertain membership are included.
The main entries of the data base are individual photoelectric UBVRI and
other photometries for approximately 70% of the foreground and 40% of the
member stars.
Most of these observations were carried out by the authors themselves.
Other important entries are spectral types, luminosity classes and radial
velocities for about 70%, 40% and 30% of the stars, respectively.
Furthermore, the galactic foreground reddening (Oestreicher et al. 1995),
the internal reddening for stars inside the LMC (Oestreicher &
Schmidt-Kaler 1996) and the absolute bolometric magnitude Mbol
(Gochermann 1994) have been determined for a significant number of objects.
New crossreferences are given, too. Table 1 gives some statistics of
the most important entries.
Table 1.
Statistics of some entries of the LMC data base
|
| foreground
| %
| member
| %
| uncertain
| %
| total
| %
|
| Number of stars
| 3260
| 30.4
| 7133
| 66.5
| 332
| 3.1
| 10725
| 100.0
|
| UBV photometry
| 2101
| 64.4
| 2470
| 34.6
| 60
| 18.1
| 4632
| 43.2
|
| BVRI photometry
| 36
| 1.1
| 735
| 10.3
| 121
| 36.4
| 892
| 8.3
|
| JHK photometry
| 9
| 0.3
| 510
| 7.1
| 7
| 2.1
| 526
| 4.9
|
| (u)vby photometry
| 58
| 1.8
| 113
| 1.6
| 1
| 0.3
| 172
| 1.6
|
| Spectral type
| 2340
| 71.8
| 5272
| 73.9
| 55
| 16.6
| 7669
| 74.5
|
| Luminosity class
| 687
| 21.1
| 3512
| 49.2
| 37
| 11.1
| 4236
| 39.5
|
| Radial velocity
| 2357
| 72.3
| 1032
| 14.5
| 39
| 11.7
| 3430
| 31.9
|
[Click here to see Fig. 1 and Fig. 2!]
The publication of the data base at CDS is planned.
Informations about individual stars can be requested from M.O. Oestreicher.
References
- Gochermann J., Grothues H.-G., Oestreicher M.O., Berghöfer Th.,
Schmidt-Kaler Th., 1993, A&AS 99, 591
- Gochermann J., 1994, AG Abstract Series 11, 19
- Grothues H.-G., Oestreicher M.O., Gochermann J., Tappert C., Zaum A.,
Brugger H.R., Schmidt-Kaler Th., 1997, A&AS 121, 237
- Isserstedt J., 1975, A&AS 19, 259
- Isserstedt J., 1979, A&AS 38, 239
- Isserstedt J., 1982, A&AS 50, 71
- Oestreicher M.O., Gochermann J., Schmidt-Kaler Th., 1995, A&AS 112, 495
- Oestreicher M.O., Schmidt-Kaler Th., 1996, A&AS 117, 112
- Schmidt-Kaler Th., 1982, The Physical Parameters of the Star, in:
Landolt-Börnstein, ed. K.-H. Hellwege, New Series Vol. VI, 2b,
Springer, Berlin, Heidelberg, New York, p.1ff
- Schmidt-Kaler Th., Gochermann J., Oestreicher M.O., Grothues H.-G.,
Tappert C., Zaum A., Berghöfer Th., Brugger H.R., 1998, MNRAS,
submitted
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| First version: | 18th | June, | 1998
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| Last update: | 30th | September, | 1998
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Jochen M. Braun &
Tom Richtler
(E-Mail: jbraun|richtler@astro.uni-bonn.de)