The starDY Persei is the prototype of this tiny class of variable stars. Only DY Persei itself was known in our galaxy until 2008 when systematic catalogue searches for R CrB variables discovered a 17th magnitude (at maximum) example.[1] Since then automated searches have confirmed another four, including one of magnitude 5.9 at maximum.[2] There are also several candidates that have not yet been observed to fade, and several DY Per stars in theLarge Magellanic Cloud.[3]
Although DY Persei variables have been considered a subset of the R CrB variables because of their irregular fades and carbon-rich spectra, they may simply be an unusual type ofcarbon star unrelated to the more massive and more luminous R CrB variables. The fades may be caused by obscuring ejection events rather than carbon condensation in the atmospheres of the stars.[2]
^Tisserand, P.; Marquette, J. B.; Wood, P. R.; Lesquoy, É.; Beaulieu, J. P.; Milsztajn, A.; Hamadache, C.; Afonso, C.; Albert, J. N.; Andersen, J.; Ansari, R.; Aubourg, É.; Bareyre, P.; Charlot, X.; Coutures, C.; Ferlet, R.; Fouqué, P.; Glicenstein, J. F.; Goldman, B.; Gould, A.; Gros, M.; Haissinski, J.; De Kat, J.; Le Guillou, L.; Loup, C.; Magneville, C.; Maurice, É.; Maury, A.; Moniez, M.; et al. (2008). "R Coronae Borealis stars in the Galactic bulge discovered by EROS-2".Astronomy and Astrophysics.481 (3): 673.arXiv:0801.1680.Bibcode:2008A&A...481..673T.doi:10.1051/0004-6361:20078814.S2CID54730211.
^abMiller, A. A.; Richards, J. W.; Bloom, J. S.; Cenko, S. B.; Silverman, J. M.; Starr, D. L.; Stassun, K. G. (2012). "Discovery of Bright Galactic R Coronae Borealis and Dy Persei Variables: Rare Gems Mined from Acvs".The Astrophysical Journal.755 (2): 98.arXiv:1204.4181.Bibcode:2012ApJ...755...98M.doi:10.1088/0004-637X/755/2/98.S2CID118556935.
^Tisserand, P.; Wood, P. R.; Marquette, J. B.; Afonso, C.; Albert, J. N.; Andersen, J.; Ansari, R.; Aubourg, É.; Bareyre, P.; Beaulieu, J. P.; Charlot, X.; Coutures, C.; Ferlet, R.; Fouqué, P.; Glicenstein, J. F.; Goldman, B.; Gould, A.; Gros, M.; De Kat, J.; Lesquoy, É.; Loup, C.; Magneville, C.; Maurice, É.; Maury, A.; Milsztajn, A.; Moniez, M.; Palanque-Delabrouille, N.; Perdereau, O.; Rich, J.; et al. (2009). "New Magellanic Cloud R Coronae Borealis and DY Persei type stars from the EROS-2 database: The connection between RCBs, DYPers, and ordinary carbon stars".Astronomy and Astrophysics.501 (3): 985.arXiv:0905.3224.Bibcode:2009A&A...501..985T.doi:10.1051/0004-6361/200911808.S2CID118453971.
