The question of a gradual dimming of KIC 8462852 continues to make waves, the most recent response being Michael Hippke's preprint on the arXiv site, discussed in the post immediately below. Bradley Schaefer (Lousiana State University), who published his work on the dimming he found in now digitized photographs in the archives of Harvard College Observatory, disagrees strongly with Hippke's findings and is concerned that the paper impugns the solid work being performed by DASCH (Digital Access to a Sky Century@Harvard). Below is Dr. Schaefer's response with details on the astrophotographic photometry at the heart of the issue. by Bradley E. Schaefer A few hours ago, Michael Hippke posted a manuscript to arXiv (http://arxiv.org/abs/1601.07314), and submitted the same manuscript to the Astrophysical Journal Letters (ApJLett). This manuscript claims to have found that the DASCH data produces light curves with secular trends (both systematic dimmings and brightenings) over the...

As if the Kepler star KIC 8462852 weren't interesting enough, Bradley Schaefer (Louisiana State) added to the controversy when he discovered what appeared to be a steady dimming of the star over the past century. Schaefer called the result "completely unprecedented for any F-type main sequence star," and given the discussion about KIC 8462852 as a SETI target, this raised the stakes. Something just as odd as the object's strange lightcurves was going on here, and it seemed natural to think that the dimming and the lightcurves were related. But Michael Hippke now begs to disagree. An old friend of Centauri Dreams (see, for example, his Exomoons: A Data Search for the Orbital Sampling Effect and the Scatter Peak), Hippke takes a close look at Schaefer's work and reaches a different conclusion. As he sees it, the 'dimming' of up 0.165 ± 0.013 magnitudes per century in this F3 star may actually be the result of imperfect calibration on the Harvard plates. In other words, while the...

How do we make out the odds on our survival as a species? Philosopher Nick Bostrom (University of Oxford) ponders questions of human extinction in terms of a so-called Great Filter. It's one that gives us a certain insight into the workings of the universe, in Bostrom's view, because it seems to keep the galaxy from being positively filled with civilizations. Somewhere along the road between inert matter and transcendent intelligence would be a filter that screens out the vast majority of life-forms, keeping the population of the galaxy low, and offering us a way to gauge our own chances for survival. Think of it this way. Perhaps the Great Filter has to do with the formation of life itself. If that is the case, then we have already made it through the filter and can go about exploring the universe. But if the Great Filter is in our future, then we can't know exactly what it will be, and neither can we know whether we will survive it. Here the final term in Frank Drake's equation...

I hadn’t expected a new paper on KIC 8462852 quite this fast, but hard on the heels of yesterday’s article on the star comes “KIC 8462852 Faded at an Average Rate of 0.165±0.013 Magnitudes Per Century From 1890 To 1989,” from Bradley Schaefer (Louisiana State University). Schaefer takes a hard look at this F3 main sequence star in the original Kepler field not only via the Kepler data but by using a collection of roughly 500,000 sky photographs in the archives of Harvard College Observatory, covering the period from 1890 to 1989. The Harvard collection is vast, but Schaefer could take advantage of a program called Digital Access to a Sky Century@Harvard (DASCH), which has currently digitized about 15 percent of the archives. Fortunately for us, this 15 percent covers all the plates containing the Cygnus/Lyra starfield, which is what the Kepler instrument focused on. Some 1581 of these plates cover the region of sky where KIC 8462852 is found. What Schaefer discovers is a secular...

As I sat down to write yesterday morning, I realized there was a natural segue between the 1977 ‘Wow!’ signal, and the idea that it had been caused by two comets, and KIC 8462852, the enigmatic star that has produced such an interesting series of light curves. What I had planned to start with today was: “Are comets becoming the explanation du jour for SETI?” But Centauri Dreams reader H. Floyd beat me to the punch, commenting yesterday: “Comets are quickly earning the David Drumlin Award for biggest SETI buzzkill.” As played by Tom Skeritt, David Drumlin is Ellie Arroway’s nemesis in the film Contact, willing to knock down the very notion of SETI and then, in a startling bit of reverse engineering, turning into its champion as he claims credit for a SETI detection. And of course you remember controversial KIC 8462852 as the subject of numerous media stories first playing up the idea of alien mega-engineering, and then as quickly declaring the problem solved by a disrupted family of...

The famous Wow! signal, picked up on August 15, 1977 at the Big Ear radio telescope (Ohio State University) is back in the news, with a new theory suggesting a source for the signal right here in the Solar System. Antonio Paris (St. Petersburg College, FL) asks us to consider a cometary origin for the signal, generated as two comets released hydrogen as they passed near the Big Ear's search field. The now-dismantled telescope had a fixed field of view, so a bright signature at 21 centimeters -- the hydrogen line -- would have appeared short-lived. Specifically, 21-cm refers to the line in the spectrum of neutral hydrogen atoms, a wavelength corresponding to 1420 megahertz associated with the most common element in the universe. It was back in 1959 that both Philip Morrison and Frank Drake fixed on the hydrogen line as a rational place to look for interstellar beacons, the assumption being that any civilization trying to reach another would choose a wavelength associated with some...

I can think of few things as spectacular as a globular cluster. Messier 5 is a stunning example in Serpens. With a radius of some 200 light years, M5 shines by the light of half a million stars, and at 13 billion years old, it's one of the older globular clusters associated with our galaxy. Clusters like these orbit the galactic core, stunning chandeliers of light packed tightly with stars. The Milky Way has 158 known globulars, while M31, the Andromeda galaxy, boasts as many as 500. Giant elliptical galaxies like M87 can have thousands. Image: The globular cluster Messier 5, consisting of hundreds of thousands of stars. Credit: ESA/Hubble & NASA. Via Wikimedia Commons. Given the age of globular clusters (an average of ten billion years), it's a natural assumption that planets within them are going to be rare. We would expect their stars to contain few of the heavy elements demanded by planets, since elements like iron and silicon are created by earlier stellar generations. And...