3C 66A is what is known as a blazar, a class of highly variable quasars known also to be emitters of gamma rays. 3C 66A can vary on timescales of hours and days, a remarkable fact since it is located hundreds of millions of light-years away. Blazars and quasars are not stars,...
May 4, 2012 - 5:53pm
AC Andromedae is notable as a triple-mode radial pulsator, with three distinct periods at 0.711, 0.525, and 0.421 days. These periods interact with one another, producing an incredibly complex beat pattern in the light curve. No two nights of observation are ever the same, and you...
April 22, 2011 - 12:09pm
If you look at the whole light curve, you can almost convince yourself that AC Herculis has a regular pulsation pattern, but when you start to look more closely, you'll see that the picture gets confusing. AC Her is an RV Tauri star, a highly evolved giant star that probably...
August 17, 2010 - 9:54am
AE Ursae Majoris is a short-period, high-amplitude delta Scuti star, a pulsating variable close to the main sequence. The delta Scuti stars, once given the moniker "dwarf Cepheids", are stars slightly more massive than our Sun that pulsate with...
December 11, 2012 - 4:02pm
AM Cas is a dwarf nova with a busy light curve. A typical dwarf nova might show outbursts of several magnitudes interspersed with occasional stretches of quiescence where it only varies by a magnitude at most. AM Cas is a little different in that it appears to be continuously...
July 26, 2010 - 2:16pm
AM Herculis is the class prototype of the polars -- cataclysmic variables whose white dwarf primaries have strong magnetic fields. Cataclysmic variables are binary stars in which the primary is a white dwarf star that accretes matter from the secondary star in the binary pair. ...
April 19, 2011 - 1:54pm
AR Pavonis is the second of the symbiotic light curves we're highlighting in this series of three. AR Pav is one of the more interesting symbiotics in that it's one of the few that shows clear evidence of eclipses of the secondary. In SY Mus we noted that the wave-like...
January 31, 2012 - 3:34pm
This is a nice example of a single-night's work on a very busy star, the SX Phoenicis variable BL Cam. BL Cam is a pulsating variable, and the light changes are caused by radial pulsations -- the surface of the star is expanding and contracting as well as changing in temperature, and...
August 23, 2012 - 10:40am
Although Z Andromedae has been observed for slightly longer, the symbiotic star CH Cygni has been more intensely observed and has historically reached brighter limits than the class prototype Z And. CH Cyg is a fine variable currently varying between magnitude 7 and 11. The star...
August 25, 2010 - 1:48pm
The symbiotic star, CI Cyg, has experienced only a few outbursts in its long recorded history. The outbursts of 1911 and 1937 were relatively modest in amplitude and duration. Then, between 1970 and 1978 CI Cyg experienced a major outburst phase, characterized by three maxima occurring on...
May 30, 2012 - 9:10am
Delta Scorpii is a bright variable of the gamma Cassiopeiae type. The gamma Cas stars are a class of Be stars, which are young, hot, massive stars believed to be rapidly rotating and losing mass. While Be stars undergo small amplitude variations, the gamma Cas...
May 4, 2012 - 2:59pm
DO Draconis is a DQ Herculis star or Intermediate Polar. It's a cataclysmic variable with a magnetic white dwarf. The term intermediate is used to describe white dwarf stars whose magnetic field strengths are a few million Gauss -- enormous by...
September 28, 2010 - 2:36pm
DQ Herculis (Nova Herculis 1934) was an exceptional nova in outburst, and remains an important object in astrophysics. The light curve shows the first 5000 days of the DQ Her lightcurve. Most notably, it shows the precipitous drop in light starting 100 days after outburst, and dropping...
December 11, 2012 - 12:39pm
DY Per is the prototype of what is believed to be a distinct class of variable star. While they exhibit some properties in common with the R Coronae Borealis stars, their fades occur with great regularity and apparently with the same period as their orbital periods when those...
September 10, 2012 - 10:21am
2009 brought an eclipse of a prominent northern hemisphere binary star with an orbital period of several years, and a number of observers obtained excellent photometry highlighting important changes in the eclipse over time.
Nope, not epsilon Aurigae, but EE Cephei, an eclipsing...
March 18, 2011 - 1:33pm
The bright southern variable eta Carinae is one of the most famous examples of a rare class of variable -- the S Doradus or Luminous Blue Variable stars. Eta Car is a giant of a star in all possible senses of the word. Its enormous size and luminosity arise from the fact that it is...
December 11, 2012 - 12:11pm
FG Sge is a very peculiar variable star whose antics have shed light on the very late stages of stellar evolution. The object is believed to be a star in the process of ejecting multiple shells of matter, forming the planetary nebula that surrounds it as we watch. Historical data...
February 8, 2011 - 8:59am
g Herculis is a bright semiregular variable of the SRb subclass that exhibits a number of interesting features in its light curve. Although a period of 89.2 days is the one noted in VSX, there's also a much more prominent variation of a half magnitude or more with a period over 800...
January 22, 2013 - 4:18pm
Gamma Cas is the class prototype for a particularly interesting class of eruptive variables. Gamma Cas was, as its name implies, a bright star in Cassiopeia, and up to 1927 was known only as an emission line star of spectral type B....
October 8, 2010 - 2:45pm
GK Persei, or Nova Persei 1901, was a famous classical nova that nearly reached magnitude 0 in the first year of the last century. It took GK Per several years to return to its faint state, but even now its quiescence is remarkably unquiet. Within a few decades of outburst GK Per...
