The macho project large magellanic cloud variable star inventory. IV. New R coronae borealis stars

Authors

C. Alcock, Lawrence Livermore National Laboratory
R. A. Allsman, University of California, Berkeley
D. R. Alves, University of California, Davis
T. S. Axelrod, University of Washington
A. Decker, Louisiana State University
D. P. Bennett, Australian National University, Mount Stromlo Observatory
G. C. Clayton, University of California, San Diego
K. H. Cook, South African Astronomical Observatory
K. C. Freeman, University of California, Santa Barbara
K. Griest, University of Oxford
J. A. Guern, McMaster University
D. Kilkenny, Lawrence Livermore National Laboratory
M. J. Lehner, University of California, Berkeley
S. L. Marshall, University of California, Davis
D. Minniti, University of Washington
B. A. Peterson, Louisiana State University
M. R. Pratt, Louisiana State University
P. J. Quinn, Australian National University, Mount Stromlo Observatory
A. W. Rodgers, University of California, Davis
C. W. Stubbs, University of California, San Diego
W. Sutherland, University of California, Santa Barbara
D. Welch, University of California, Berkeley

Document Type

Article

Publication Date

1-1-1996

Abstract

We report the discovery of two new R Coronae Borealis (RGB) stars in the LMC using the MACHO project photometry database. The identification of both stars has been confirmed spectroscopically. One is a cool RGB star (Teff ∼ 5000 K), characterized by very strong Swan bands of C2 and violet bands of CN, and weak or absent Bahner lines, G band, and 12C13C bands. The second star is an example of a hot RGB star, of which only three were previously known to exist in the Galaxy and none in the LMC. Its spectrum is characterized by several G n lines in emission. Both stars have shown deep declines of Δ F ≥ 4 mag in brightness. The new stars are significantly fainter at maximum light than the three previously known LMC RGB stars. The amount of reddening toward these stars is somewhat uncertain, but both seem to have absolute magnitudes, MV, ∼0.5 mag fainter than the other three stars. Estimates of Mbol find that the hot RGB star lies in the range of the other three stars, while the cool RGB star is fainter. The two cool LMC RGB stars are the faintest at Mbol. The discovery of these two new stars brings to five the number of known RGB stars in the LMC, and it demonstrates the utility of the MACHO photometric database for the discovery of new RGB stars. © 1996. The American Astronomical Society. All rights reserved.

Publication Source (Journal or Book title)

Astrophysical Journal

First Page

583

Last Page

590

Recommended Citation

Alcock, C., Allsman, R., Alves, D., Axelrod, T., Decker, A., Bennett, D., Clayton, G., Cook, K., Freeman, K., Griest, K., Guern, J., Kilkenny, D., Lehner, M., Marshall, S., Minniti, D., Peterson, B., Pratt, M., Quinn, P., Rodgers, A., Stubbs, C., Sutherland, W., & Welch, D. (1996). The macho project large magellanic cloud variable star inventory. IV. New R coronae borealis stars. Astrophysical Journal, 470 (1 PART I), 583-590. https://doi.org/10.1086/177890