March 18, 2019

Astro-Challenge: The Ruddy Hues of UU Aurigae.

Carbon stars are some of our “surprise faves” to show off to folks when it comes to variable stars. Objects like V Hydrae and R Leporis, otherwise known as Hind’s Crimson Star exhibit a cherry red hue as they fatten up on carbon fusion and filter through red-wavelength light late in their stellar careers. This week, I’d like to challenge you to point your scope high in the January evening sky at another colorful wintertime sight to add to your repertoire, UU Aurigae, a variable star located along the Gemini/Aurigae border. This star varies from a maximum brightness of +5 to a minimum of +7 to +10 with two superimposed periods of 233 and 438 days. UU Aurigae just came off of a minimum magnitude around +7 in the early Fall of 2011 and should be headed towards a maximum of +5 in spring of this year.

Created by Author in Starry Night, north is to the left.

A C5II-type star on the Morgan-Keenan C System of carbon abundance, UU Aurigae has an R-I color index of +1.43 (Hind’s, one of the reddest stars in the sky has a R-I of +1.47 for context) and is classified as a semi-regular variable. Observers report its color as a deep orange-to-red, and it’s always an interesting study to note how the color of such stars changes as they approach maximum. UU Aurigae lies 5 degrees NW of the +3.6 magnitude close double star (at 2.9” arc seconds of separation) Theta Geminorum. Its coordinates are:

Right Ascension: 06 Hours, 36.5’

Declination: +38° 27’

Good luck, and let us know about your respective observing anecdotes as you track down this ruby-tinged wonder.

In other astronomical events of note this week, the +14.8 magnitude asteroid 911 Agamemnon occults a +7.8 magnitude star in the constellation of the Lynx. The 200 kilometer-wide path will cover a stretch of the Earth’s surface touching down along the U.S. east coast across New Jersey-Virginia at 11:31 UT on January 19th, tracking across central Canada and Alaska before departing our planet over Siberia and Mongolia at 11:41 UT.  If you’ve never caught an asteroid occultation of a star, this would be a fine one to watch, and one of the better events of 2012.

Also Comet P/2006 T1 Levy reached a perihelion of 1.007 astronomical units from the Sun on January 14th and was predicted to have attained magnitude +7 by now as it crossed from Pisces into Cetus on the 17th; however, current observations place it more along the lines of less than +17 magnitude visually. It is suspected that the comet was in outburst when first discovered by David Levy from Jarnac observatory in Vail, Arizona (only miles away from the now defunct Very Small Observatory of Astroguyz fame.) The comet has apparently pulled an “Elenin” and disintegrated… hopefully, dependable Comet C/2009 P1 Garradd continues its track record as a fine binocular comet in the morning skies this spring.  Also sometimes listed by its recovery designation of P/2011 Y1 Levy, it’s still amusing to watch as certain unnamed and obviously automated sites continue to list P/2006 T1 Levy as a bright comet! Need a human astro-fact checker there, guys? Comet P/2006 T1 Levy will also make its closest approach to Earth on January 26th at just shy of 22 million miles (about 88x the Moon’s orbital radius) distant.

Finally, we’ve been following the stranded Russian Phobos-Grunt spacecraft on every pass over Astroguyz HQ this past week; the most recent updated projections for re-entry stands at 14:35 UTC on January 15th, ±1 day. This all assumes, of course, that the probe hasn’t already re-entered as you’re reading this! Interestingly, we have a visual pass over a local Star Party that we’re attending Saturday night January 15th! Come on out to Starkey Park if you’re in the New Port Richey area; you just might see UU Aurigae and a satellite re-entry to boot! Incidentally, rough back-of-the-envelope calculations for seeing Phobos-Grunt re-entering while above your local horizon (assuming you live between latitudes 50° north or south, along with about 95% of the human population) are about 300-to-1 against; a long shot, but better than the lottery! Also, the Phobos-Grunt saga has spun off a whole host of bizarre (and of course, web circulating) tales, proof of the Mark Twain  adage that a lie can fly around the world while the truth is “just putting on its shoes…” Not the least of which are that the probe will “hit Afghanistan” (the aforementioned odds for such a prediction aren’t much better for them than any other country) and that the HAARP array in Alaska had something to do with disabling the probe. (The failure occurred before the passage of the spacecraft over HAARP) still, we’re going to miss explaining the name “Phobos-Grunt” to friends and family, many who are already convinced that us astro-bloggers are a bit “off our rockers,” anyway!