Variable Stars - CI Cam
Type HMXB; LERI; XN Click for lightcurve HMXB High Mass X-ray Binaries. Systems with a massive star (usually an O or B star, a Be star or a blue supergiant) and a compact object (generally a neutron star, a black hole or a white dwarf). A fraction of the stellar wind of the normal star is captured by the compact object and produces X-rays as it falls onto it or onto an accretion disk that's surrounding it. In X-ray binaries, the subtypes indicate which kind of behavior the binary displays, like X-ray bursts (XB), large amplitude outbursts also in the visual (XN), reflection effect (XR) or it may also inform about the object's nature, e.g.: if the compact object is a pulsar (XP). Refer to the subtypes list below. LERI λ Eri type variables. Be stars with the light variation caused by rotational modulation or non-radial pulsations. Their light curves are usually double-waved and with changing amplitude. Periods in the order of 0.3 - 3 d. XN X-ray systems that occasionally rapidly increase in brightness by 1-9 mag. in V simultaneously with the X-ray range. AAVSO Alert Notice 559, 19 October 2016 Observations of CI Cam needed to support spectroscopy Kelly Gourdji and Marcella Wijngaarden (graduate students at the University of Amsterdam/Anton Pannekoek Institute for Astronomy) have requested AAVSO observers' assistance in providing optical photometry of CI Cam in support of their high-resolution spectroscopy with the Mercator telescope + Hermes spectrograph in La Palma from now through January 2017. They write: "...We are currently observing the variable star CI Cam (the B[e] optical counterpart of a HMXB system) with the HERMES spectrograph at the Mercator Telescope in La Palma. Having observed the star for three nights now, the object appears to be in outburst. In particular, H alpha was measured to be 80 times the continuum flux, and increasing between Oct. 9 and 12. This is similar to the previous outburst in 2004/5. Photometric data obtained during the 2004/5 outburst suggested an outburst duration of about 3 months and a peak brightness of 11.2 in the V band." More information is available in ATel #9634 (Wijngaarden et al.; www.astronomerstelegram.org/?read=9634). Multiple snapshot observations per night in BVRI are requested beginning immediately and continuing through January 2017. Time series are not necessary unless requested later via an AAVSO Special Notice. Observations made using other filters will be useful as well as long as there are multiple observations in these bands. Unfiltered observations are also useful but preferably only when they are available for multiple nights (in order to cross-match with other observations). CI Cam has a V range of 9.5-11.9.
Hills Observatory: 1 January 2013 to 16 November 2018
COMETS COMETS
DEEP SKY DEEP SKY