WR104 : Large amplitude variation in a Wolf-Rayet star

K. Haseda reported the discovery of a new variable star (HadV82). The star is identified with an IR-luminous WR-type star, WR104. The striking spectroscopic variability WR104, probably associated with photometric fading, was previously reported by Crowther, MNRAS 290, L59 (1997). The suggested photometric fading by Crowther (1997) was based on a comparison with previously published photometry, and was not very conclusive. Crowther (1997) also added that past research had found no infrared variability. Crowther (1997) suggested this phenomenon to be dust condensation as seen in R CrB-type stars, but the nature of variation remained an mystery. This discovery by Haseda has not only shown that the object is indeed variable in optical, but also that bright and faint states appear interchangebly, with a characteristic time scale of one to a few years (vsnet-campaign 863). Since the rotation period of the spiral (Tuthill et al. 1999, Nature 398, 487: "A dusty pinwheel nebula around the massive star WR 104") is reported to be 220 d, observations at higher frequencies are encouraged (vsnet-campaign 865). Based on the detailed chart prepared by T. Watanabe, K. Haseda further provides the updated set of photographic photometry which shows the variability range is 11.8-(14.5p (vsnet-campaign 868). S. Kiyota reported magnitudes of Ic=10.14, V=12.70, and B=14.7: on April 22 (vsnet-campaign 873). T. Kato performed period analysis using the reported data to VSNET and yield 220+/-30d periodicity which may be identical with the binary period (vsnet-campaign 888). On the contrary, C. Lloyd reported the best period at 2180+/-130 days, corresponding to the clear variation in the data (vsnet-campaign 889).

Other related articles: vsnet-campaign 869, 876, 877, vsnet-campaign-data 62, 63

Finding chart presented by T. Watanabe; http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-j/jpg00010.jpg
VIIth catalogue of galactic WR stars: ftp://saturn.sron.nl/pub/karelh/UPLOADS/VIIWRCAT.pdf

Light Curve of This Object