May 23, 2017

16.05.10- Gliese 710: A Future Stellar Threat?


Gliese 710 inbound…(Credit: The Sloan Digital Sky Survey).

   Our quiet corner of the local galaxy may be in for a future interloper. A possible solar system side-swipe comes in the form of Gliese 710, an unassuming +10 magnitude orange dwarf star currently 63 light years distant in the constellation Serpens. As we swirl around the center of our galaxy, stellar neighbors come and go like in-laws during your favorite respective obligatory familial holiday season. The low proper motion of this star hid its true nature until about a decade ago; generally, the lower the apparent motion, the more distant the star. Gliese 710, however, fits into a different class; a star that shows a low apparent motion because it’s moving towards us. Closest approach has been calculated by astronomer Joan Garcia-Sanchez of JPL as about 1.3 light years in 1.5 million years time. Doesn’t sound like much? Well, this skirts the edge of our Oort Cloud, that vast reservoir of comets that extends out to about 1.6 light years distant…Gliese 710 stands an 86% chance of breaking this threshold. In addition, a 2007 review of Hipparcos data by Vadim V. Bobylev shows that this star may pass as close as 0.02 of a light year, about 50 times farther than the (sometimes) planet Pluto. This could make things really interesting, as Gliese 710 could really stir things up in our Oort cloud. And of course, there is the question of whether or not Gliese 710 has an Oort Cloud of its own. More than likely, this pulse of comets will last for about a several million year span of time. Could our inner solar system have sustained such shocks before? One only has to look at the crater-scarred surface of our Moon to realize the inner solar system has served as a shooting gallery over the eons. The statistical probability of a really (i.e. 1,000 AU) approach is about 1 in 10,000, so don’t max out those credit cards just yet… this uncertainly stems from incomplete knowledge of all the gravitational factors at work. As more sensitive astrometrical platforms, such as ESA’s Gaia spacecraft come online, the nature of the threat from Gliese 710 will be more precisely known. At its closest approach, this inbound star will be about as bright as the red giant star Antares… here’s to the neighbors!

Space Telescopes, Part I: Optical.

(Credit: NASA/ESA/S. Gallagher/J. English).
(Credit: NASA/ESA/S. Gallagher/J. English).

 Hickson Group 31 of galaxies as imaged by Hubble.

   This weeks’ expose will kick off our four part series on orbiting space telescopes. For starters, we’ll begin with the most familiar; the optical wavelength. True, we as humans are biased towards this narrow band of the spectrum; we love to see pretty pictures that we can relate to.  But beyond this, telescopes that operate in the visual wavelengths have no less than revolutionized astronomy, as well as laid promise for perhaps giving us images of exo-Earths in our lifetimes. What follows is a rapid fire list of what was, is, and what to look for up and coming in the realm of optical astronomy in space: [Read more...]

When You Wish Upon a Star: the Truth About Star Naming.

    We have a pet peeve here at Astroguyz. Every great once in a while, most astronomers get asked by a well meaning member of the public to locate a particular star. This is not a problem, even without the benefit of a “Goto” mount; right ascension, declination, and maybe a crude star map is all that is required. [Read more...]