HT Cassiopeiae is an eclipsing dwarf nova of the SU Ursae Minoris (UGSU) subclass. The UGSU typically undergo occasional short normal outbursts punctuated by rarer superoutbursts that are brighter and longer than usual. HT Cas last underwent a superoutburst in late 2010, lasting...
November 7, 2012 - 2:07pm
Here's a light curve that just looks cool -- the eclipsing dwarf nova IP Pegasi, where the eclipses were tracked during a recent outburst. Dwarf novae consist of a pair of stars, one a normal dwarf star, and the other a degenerate white dwarf. The stars orbit close...
July 30, 2012 - 8:51am
IW Andromedae is a member of the Z Camelopardalis class of cataclysmic variables, which are dwarf novae with higher-than-average mass accretion rates. These stars will occasionally get "stuck" in a high state between quiescence and full outburst, sometimes remaining there for...
July 18, 2010 - 12:11pm
Khi Cygni is one of the longest-studied variable stars, having been discovered in the 17th Century. Khi Cyg (also spelled "chi Cyg") is a bright Mira variable, a pulsating star near the end of its life with a period of about 400 days, and an enormous amplitude of 10 magnitudes...
July 30, 2012 - 8:39am
KR Aurigae is a cataclysmic variable of the VY Sculptoris class, characterized by long periods of time spent in a bright state punctuated by occasional time spent in a very faint low state. The high state is characteristic of the novalike variables with high mass transfer rates, while...
July 18, 2010 - 12:31pm
KT Eri is a classical nova that erupted in late 2009. This nova (Nova Eri 2009) reached magnitude 5.5 in mid-November. It declined to about magnitude 11.5 by mid-February 2010, but remained fairly constant throughout the rest of the 2009-2010 season, with irregular flickering of...
July 26, 2010 - 1:36pm
Mu Cephei (or "miu Cep") is a bright, red semiregular supergiant (type SRc) star, varying between 3rd and 6th magnitude. It was dubbed "The Garnet Star" by William Herschel in 1783, and has been known to be variable since the mid-19th Century. Mu Cephei is a...
April 16, 2012 - 9:13am
OJ 287 is a bright BL Lac object, also known as a blazar. Blazars are supermassive black holes that reside at the centers of distant galaxies. As the black hole accretes matter from the galaxy, some of this material is launched into space away from the...
September 28, 2010 - 3:23pm
Omicron Ceti, also known as Mira, is justifiably one of the most famous of the variable stars, and dear to many variable star observers -- especially those who use our website, mira.aavso.org! Omi Cet, discovered in 1596, was declared 'miraculous' by its early observers for...
October 28, 2011 - 8:11am
A casual observer of R Aquarii over the past several decades might've noticed something slightly out of the ordinary with this Mira variable, as the depth of its minimum seems to undulate slowly over the course of many years. An observer of the 1920s and 1930s would've seen...
February 10, 2011 - 10:16pm
R Aurigae is a fine, bright, long-period Mira variable that's been well-observed by the amateur community for well over a century. It's period of 450 days is high for the optically bright Miras, but periods can be much longer for some of the dust-enshrouded Miras and pulsating OH...
November 7, 2012 - 3:50pm
R Caeli is a fine southern Mira with large amplitude and period just under 400 days. It's one of our LPV Program stars, as well as being one of the LPVs with "humps". In this stretch of the light curve, there's a shoulder during rising light, and it's also...
November 6, 2012 - 11:52am
R Capricorni is an equatorial Mira accessible to most observers except those in the far northern hemisphere. It's a carbon Mira with a strongly varying light curve and period close to one year -- about 343 days. The AAVSO Bulletin predicts a...
November 2, 2010 - 10:21am
R Centauri has long been identified as a peculiar Mira variable showing prominent double maxima. The star reaches a local maximum -- one slightly fainter than the other -- with each pulsation cycle of around 550 days. The physical cause of this isn't clear, but one...
July 18, 2010 - 12:26pm
R Coronae Borealis stars (or R CrB stars) are highly evolved stars whose light undergoes dramatic dimming events caused by dust around the star. In mid-2007, the class prototype entered one of these dimming events, and has yet to return to its normal brightness. Astronomers use the...
August 6, 2010 - 1:09pm
R Scuti is a popular target for variable star observers and has been for well over a century (its observational record dates to the late 18th century). R Scuti is an RV Tauri star, which are highly evolved pulsating giant stars having periods from tens of days to 100 days or more....
October 1, 2010 - 3:50pm
RR Pic (Nova Pictoris 1925) is an example of a slow nova, which are classical nova systems whose light output changes on timescales of months and years rather than the days and weeks of typical novae. Slow novae are believed associated with lower-mass white dwarf primaries, perhaps as...
September 28, 2010 - 3:10pm
RR Tauri is an incredibly active young stellar object -- a star still in the process of forming. RR Tau is an emission-line star belonging to the HAeBe class, which are stars with spectral types A or B, emission lines, and show signs of nearby nebulosity. It is also a variable star...
July 16, 2012 - 1:34pm
RU Herculis is another Mira with strongly varying cycle-to-cycle behavior. It has a high amplitude, approaching nine magnitudes from peak to trough on some cycles, although six magnitudes is more typical. As is often the case with large-amplitude stars, the light curves are...
February 7, 2011 - 10:40am
RU Lupi is one of many T Tauri variables under observation by the amateur community. These stars are young objects, still accreting matter from the dust and gas clouds from which they form. In this case, RU Lup sits in the midst of a large dust cloud clearly visible against the...
