Latest Variable star Stories

Astronomers facing Socratic "ignorance"An extensive study made with ESO's Very Large Telescope deepens a long-standing mystery in the study of stars similar to the Sun. Unusual year-long variations in the brightness of about one third of all Sun-like stars during the latter stages of their lives still remain unexplained. Over the past few decades, astronomers have offered many possible explanations, but the new, painstaking observations contradict them all and only deepen the mystery. The...

Cataclysmic variable starsThis week, Astronomy & Astrophysics publishes a somewhat unusual research article because it is co-authored by German high-school students. Led by astronomer Klaus Beuermann (University of Göttingen, Germany), the team [1] involves a secondary school physics teacher, three students from two high schools in Göttingen [2], and three professional astronomers. The team made use of a remotely-controlled 1.2-meter telescope in Texas [3], funded by the Alfried...

Ohio State University researchers have found a way to measure distances to objects three times farther away in outer space than previously possible, by extending a common measurement technique.They discovered that a rare type of giant star, often overlooked by astronomers, could make an excellent signpost for distances up to 300 million light years -- and beyond.Along the way, they also learned something new about how these stars evolve.Cepheid variables -- giant stars that pulse in...

Whatever dark energy is, explanations for it have less wiggle room following a Hubble Space Telescope observation that has refined the measurement of the universe's present expansion rate to a precision where the error is smaller than five percent. The new value for the expansion rate, known as the Hubble constant, or H0 (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometers per second per megaparsec (error margin of ± 3.6). The...

Pulsating stars enable a new precise determination of the rotation of our GalaxyNew, very precise measurements have shown that the rotation of the Milky Way is simpler than previously thought. A remarkable result from the most successful ESO instrument HARPS, shows that a much debated, apparent 'fall' of neighborhood Cepheid stars towards our Sun stems from an intrinsic property of the Cepheids themselves.The result, obtained by a group of astrophysicists led by Nicolas Nardetto, will soon...

Discovery helps solve riddle of where the carbon white dwarfs come from, and what happens to their hydrogen and heliumUniversity of Texas at Austin astronomers Michael H. Montgomery and Kurtis A. Williams, along with graduate student Steven DeGennaro, have predicted and confirmed the existence of a new type of variable star, with the help of the 2.1-meter Otto Struve Telescope at McDonald Observatory. The discovery is announced in today's issue of Astrophysical Journal Letters.This research...

Astronomers calibrate the distance scale of the UniverseTaking advantage of the presence of light echoes, a team of astronomers have used an ESO telescope to measure, at the 1% precision level, the distance of a Cepheid - a class of variable stars that constitutes one of the first steps in the cosmic distance "Our measurements with ESO's New Technology Telescope at La Silla allow us to obtain the most accurate distance to a Cepheid," says Pierre Kervella, lead-author of the paper...

VLTI Snapshots Dusty Puff Around Variable StarUsing ESO's Very Large Telescope Interferometer, astronomers from France and Brazil have detected a huge cloud of dust around a star. This observation is further evidence for the theory that such stellar puffs are the cause of the repeated extreme dimming of the star.R Coronae Borealis stars are supergiants exhibiting erratic variability. Named after the first star that showed such behaviour [1], they are more than 50 times larger than our Sun. R...

ESO -- Using ESO's Very Large Telescope Interferometer (VLTI) at Cerro Paranal, Chile, and the CHARA Interferometer at Mount Wilson, California, a team of French and North American astronomers has discovered envelopes around three Cepheids, including the Pole star. This is the first time that matter is found surrounding members of this important class of rare and very luminous stars whose luminosity varies in a very regular way. Cepheids play a crucial role in cosmology, being one of the...

WASHINGTON (Reuters) - The Hubble Space Telescope has captured the first image of a cosmic object that has been known but never before seen: a small, faint companion of the North Star.While the image released on Monday may not seem spectacular -- it's a little blurry blob beside the big star -- it helped scientists figure out the North Star's mass."This is the final piece of the jigsaw puzzle which will let us get the most prized piece of information about a star, that is, its...