The Macho project LMC variable star inventory. X. The R Coronae Borealis stars

Pontifical Catholic University of Chile, CiudadSantiago, Santiago Metropolitan, Chile
The Astrophysical Journal (Impact Factor: 5.99). 02/2001; 554(1):298. DOI: 10.1086/321369
Source: arXiv


We report the discovery of eight new R Coronae Borealis (RCB) stars in the Large Magellanic Cloud (LMC) using the MACHO project photometry database. The discovery of these new stars increases the number of known RCB stars in the LMC to thirteen. We have also discovered four stars similar to the Galactic variable DY Per. These stars decline much more slowly and are cooler than the RCB stars. The absolute luminosities of the Galactic RCB stars are unknown since there is no direct measurement of the distance to any Galactic RCB star. Hence, the importance of the LMC RCB stars. We find a much larger range of absolute magnitudes (M(V) = -2.5 to -5 mag) than inferred from the small pre-MACHO sample of LMC RCB stars. It is likely that there is a temperature - M(V)relationship with the cooler stars being intrinsically fainter. Cool (~5000 K) RCB stars are much more common than previously thought based on the Galactic RCB star sample. Using the fairly complete sample of RCB stars discovered in the MACHO fields, we have estimated the likely number of RCB stars in the Galaxy to be ~3,200. The SMC MACHO fields were also searched for RCB stars but none were found. Comment: 36 pages, Latex plus 16 additional tables. ApJ, in press

Download full-text


Available from: Andrew John Drake, Mar 04, 2013
20 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Photographic monitoring in the I(0.81), R(0.63), v, b and u passbands with the Baldone Schmidt telescope in 1975--2002, the infrared J, H, K, L and M photometry carried out in 1995--2002 with the 0.7 m telescope of the Crimean Astrophysical Observatory and with the 1.25 m telescope of the Crimean Station of the Sternberg Astronomical Institute, as well as photovisual magnitude estimates on the Sonneberg Observatory Patrol plate archive of 1963--1980 are used to study the photometric behavior of DY Per, an unusual carbon star. The characteristics of light variations of DY Per are compared with those of long period variables, RCB stars and LMC DY Per-like stars.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: During the year, astronomers provided explanations for solar topics ranging from the multiple personality disorder of neutrinos to cannibalism of CMEs (coronal mass ejections) and extra-solar topics including quivering stars, out-of-phase gaseous media, black holes of all sizes (too large, too small, and too medium), and the existence of the universe. Some of these explanations are probably possibly true, though the authors are not betting large sums on any one. The data ought to remain true forever, though this requires a careful definition of "data" (think of the Martian canals).
    Publications of the Astronomical Society of the Pacific 04/2002; 114(795):475-528. DOI:10.1086/341673 · 3.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: ES Aql, initially classified as a semiregular variable, is now believed to be a member of the R Coronae Borealis (RCB) class of stars, a small group of carbon-rich supergiants that undergo dramatic declines in brightness at irregular intervals. We present photometry of ES Aql going back as far as 1893 using plates from the Harvard College Observatory as well as more recent photoelectric and visual observations. ES Aql displays the typical behavior of an RCB star, consisting of sharp declines at irregular intervals. The spectrum of ES Aql is also typical of a cool (Teff~5000 K) RCB star, showing strong absorption bands of C2 and CN, along with weak hydrogen and no detectable 13C. ES Aql is also an IRAS source indicating the presence of dust. Based on these data, we conclude that ES Aql is indeed an RCB star.
    Publications of the Astronomical Society of the Pacific 07/2002; 114(798):846-850. DOI:10.1086/341716 · 3.50 Impact Factor
Show more