Hostname: page-component-7479d7b7d-pfhbr Total loading time: 0 Render date: 2024-07-11T22:54:58.786Z Has data issue: false hasContentIssue false
  • English
  • Français

Equilibrium Models for two Samples of OH/IR Stars

Published online by Cambridge University Press:  25 April 2016

P. te Lintel Hekkert ,
H. Dejonghe  and
H. J. Habing
P. te Lintel Hekkert
Affiliation:
Mount Stromlo and Siding Spring Observatories, Private Bag, Weston ACT 2611
H. Dejonghe
Affiliation:
Sterrenkundig Observatorium, Rijks Universiteit Gent, Krijgslaan, Gent, Belgium
H. J. Habing
Affiliation:
Sterrewacht Leiden, Leiden, The Netherlands
Get access Rights & Permissions [Opens in a new window]

Abstract

We present a progress report on the dynamical analysis of the IRAS sample of OH/IR stars. This sample is complete within a distance of 8 kpc. We distinguish two groups of OH/IR stars, one with high and the other with low expansion velocity of the circumstellar shell.

Using a quadratic programming method we fit a database of Galactic orbits to the observed distribution of radial velocities, longitudes and latitudes. The dynamical model yields a distribution function, based on two integrals of motion, for each group. Integration gives the density, the mean velocity and the velocity dispersions as function of R and z. The distribution functions for the two groups differ enough to suggest that they represent two different stellar populations.

We estimate the stellar lifetime for each group by comparing the velocity dispersions and z scale-heights at the solar radius with those found for local stellar populations. We conclude that the group with the low expansion velocity is likely to be part of the thick disc, while the high expansion velocity group has dynamical characteristics resembling an old disc population; this in contrast with the findings for differently selected samples of OH/IR stars (e.g., Baud et al. 1981a; 1981b), which were found to be less than 1 Gyr old.

Type
Invited
Information
Publications of the Astronomical Society of Australia , Volume 9 , Issue 1 , 1991 , pp. 20 - 25
Copyright
Copyright © Astronomical Society of Australia 1991

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Baud, B., Habing, H. J., Matthews, H. E., Winnberg, A., 1981, Astron. Astrophys., 95, 156.Google Scholar
Baud, B., Habing, H. J., Matthews, H. E., Winnberg, A., 1981b, Astron. Astrophys., 95, 171.Google Scholar
Bahcall, J. N., Schmidt, M., Soneira, R. M., 1982, Astrophys. J. Lett., 258, L23.CrossRefGoogle Scholar
Binney, J., Tremarne, S., 1987, Galactic Dynamics, Princeton University Press, Princeton.Google Scholar
Burton, W.B., Gordon, M. A., 1978, Astron. Astrophys., 63, 7.Google Scholar
Carlberg, R. G., Sellwood, J. A., 1985, Astrophys. J., 292, 79.CrossRefGoogle Scholar
Dejonghe, H., 1989, Astrophys. J., 343, 113. (Paper I)CrossRefGoogle Scholar
Dejonghe, H., de Zeeuw, P. T. 1988, in Mass of the Galaxy, ed. Fich, M., (Toronto University Press), p 55.Google Scholar
Eder, J., Lewis, B. M., Teman, Y., 1988, Astrophys. J. Suppl., 66, 183.CrossRefGoogle Scholar
Feast, M. 1987, in Galaxy, eds. Gilmore, G. and Carswell, B. (Reidel, Dordrecht), p 1.Google Scholar
Freeman, K., 1987, Annu. Rev. Astron. Astrophys., 25, 603.CrossRefGoogle Scholar
Fricke, W., 1952, Astron. Nachr., 280, 193.CrossRefGoogle Scholar
Gilmore, G., Wyse, R. F. G., Kuyken, K., 1989, Annu. Rev. Astron. Astrophys., 27, 555.CrossRefGoogle Scholar
Habing, H. J., 1987 1987, in Late stages of stellar evolution, eds. Kwok, S. and Pottasch, S. R., (Reidel, Dordrecht), p 291.CrossRefGoogle Scholar
Habing, H. J., 1988, Astron. Astrophys., 200, 40.Google Scholar
Herman, J., 1988, Astron. Astrophys. Suppl. Ser, 74, 133.Google Scholar
Iben, I. Jr., Renzini, A., 1983, Annu. Rev. Astron. Astrophys., 21, 271.CrossRefGoogle Scholar
Lacey, C. G., 1984, Mon. Not. R. Astr. Soc., 208, 687.CrossRefGoogle Scholar
Likkel, L., 1989, Astrophys. J., 344, 350.CrossRefGoogle Scholar
te Lintel Hekkert, P., Habing, H. J., Caswell, J. L., Norris, R. P., Haynes, R. F., 1989a, Astron. Astrophys. Suppl. Ser., submitted.Google Scholar
te Lintel Hekkert, P., Sivagnanam, P., Habing, H. J., Le Squeren, A. M., 1989b, in preparation.Google Scholar
te Lintel Hekkert, P., Dejonghe, H. 1989, in Astrophysical Discs, ed. Sellwood, J. R., (Reidel, Dordrecht), in press.Google Scholar
Olnon, F. M., 1977, PhD thesis, Leiden University.Google Scholar
Olnon, F. M., Walterbos, R. A. M., Habing, H. J., Matthews, H. R., Winnberg, A., Brzezinska, H., Baud, B., 1981, Astrophys. J. Lett., 245, L103.CrossRefGoogle Scholar
Sivagnanam, P., Le Squeren, A. M., 1986, Astron. Astrophys., 168, 374.Google Scholar
Ratnatunga, K. U., Freeman, K. C., 1989, Astrophys. J., 339, 126.CrossRefGoogle Scholar
van der Veen, W. E. C. J., Breukers, R., 1989, Astron. Astrophys., 213, 133.Google Scholar
Villumsen, J. V., 1985, Astrophys. J., 290, 75.CrossRefGoogle Scholar
Wielen, R., 1977, Astron. Astrophys., 60, 263.Google Scholar