A Strange "Comet" Among the Asteroids
January 7th's announcement that the LINEAR telescope had spotted a new periodic comet wasn't all that interesting: a 20th-magnitude blip out in the asteroid belt in a benign orbit that wouldn't come anywhere near Earth. Designated P/2010 A2 (LINEAR) by the IAU's Minor Planet Center, it was just another notch on the finderscope for this discovery machine near Socorro, New Mexico, which has chalked up 77 periodic comets (and a couple hundred one-timers) since coming online in 1998.
But as other observers chipped in positions over the next week, it became clear that this was an object worth watching. For one thing, the now-precise orbit was looking less like a comet's and more like an asteroid's. And images of the interloper showed a tail growing in length yet without a clearly defined head. The online chatter got more animated — just what was this, anyway?
On January 14th, Javier Licandro and others used the Nordic Optical Telescope in the Canary Islands to get a better view, and they discovered something completely unexpected: a small asteroid lay 2 arcseconds to P/2010 A2's east and was moving along with it. Moreover, the "comet" showed no central condensation and looked more like a narrow dust swarm about 110,000 miles (177,000 km) long.
Licandro quickly enlisted the biggest aperture in the island's observatory complex: the Gran Telescopio Canarias. Dozens of images taken three days ago using its immense 34-foot (10.4-m) aperture confirm that the "comet" is being shadowed. It's hard not to conclude that we are watching the aftermath of a collision in the asteroid belt. But it's still too early to know for sure. Licandro and his colleagues are analyzing the GTC images carefully — and they hope to make them public soon.
Meanwhile, comet specialists are hoping to observe the strange goings-on with both the Hubble and Spitzer space telescopes. Neither has been given the green light yet, but if/when that happens the observations would be made within the next few days. According to Caltech astronomer William Reach, Spitzer no longer has the ability to look deep in the infrared, but it can still record at 3.6 and 4.5 microns, where the cometary gases carbon monoxide and carbon dioxide have strong emissions.
The cometary object P/2010 A2, as captured on January 11, 2010, by the 3.5-m WIYN telescope in Arizona. Note the small distinct object (arrowed). Astronomers are trying to determine if the diffuse cloud is normal cometary outgassing or the result of a collision between two objects. For more detail about this image, click here.
J. Annis / M. Soares-Santos / D. Jewitt
On January 14th, Javier Licandro and others used the Nordic Optical Telescope in the Canary Islands to get a better view, and they discovered something completely unexpected: a small asteroid lay 2 arcseconds to P/2010 A2's east and was moving along with it. Moreover, the "comet" showed no central condensation and looked more like a narrow dust swarm about 110,000 miles (177,000 km) long.
The newfound "comet" designated P/2010 A2 has an orbit that's squarely in the asteroid belt, circling the Sun ever 3.4 years. Click here for a larger view.
JPL / SSD
Meanwhile, comet specialists are hoping to observe the strange goings-on with both the Hubble and Spitzer space telescopes. Neither has been given the green light yet, but if/when that happens the observations would be made within the next few days. According to Caltech astronomer William Reach, Spitzer no longer has the ability to look deep in the infrared, but it can still record at 3.6 and 4.5 microns, where the cometary gases carbon monoxide and carbon dioxide have strong emissions.
Posted by Kelly Beatty, January 19, 2010
Vesta in 2010
Late these evenings Leo climbs the eastern sky with the promise of the distant springtime to come. Leo's forequarters form the landmark Sickle asterism, and in and around the Sickle this season lurks the most prominent asteroid in the sky: 4 Vesta. Although Vesta is not the largest asteroid, it generally becomes the brightest around its season of opposition; its unique surface material is less dark colored than most of the stuff in the asteroid belt.
Vesta reaches opposition on the night of February 17–18, when it will shine at magnitude 6.1. (Notice that, as you'd expect, this date comes halfway through Vesta's retrograde loop on the map here.) Using the map, you can follow Vesta starting immediately. It's magnitude 7.4 as early as December 20th, when you'll have to wait up until about 11 p.m. to see Leo well risen in the east. Vesta is magnitude 7.2 on January 1st, 6.4 on February 1st, 6.2 on March 1st, 6.8 on April 1st, 7.3 on May 1st, and back down to 7.7 on June 1st. That means it's in binocular range for the whole time.
A very special coincidence happens right around opposition. Between the evenings of February 16th and 17th for the Americas, Vesta threads the gap between Gamma Leonis (magnitude 2.5) and 40 Leonis (magnitude 4.8), which is located 22 arcminutes to Gamma's south. This familiar binocular pair will have a faint new interloper! Watch the asteroid's progress from night to night — or even, with a telescope, from hour to hour. Around those dates Vesta moves northwestward by 1 arcminute in a little less than 2 hours — or, at high magnification, 1 arcsecond in a little less than 2 minutes of time.
Click here for a full-page printable chart in PDF format showing Vesta's path through the "fixed" stars in 2010.
Click on the map above for a full-page printable PDF version.
A very special coincidence happens right around opposition. Between the evenings of February 16th and 17th for the Americas, Vesta threads the gap between Gamma Leonis (magnitude 2.5) and 40 Leonis (magnitude 4.8), which is located 22 arcminutes to Gamma's south. This familiar binocular pair will have a faint new interloper! Watch the asteroid's progress from night to night — or even, with a telescope, from hour to hour. Around those dates Vesta moves northwestward by 1 arcminute in a little less than 2 hours — or, at high magnification, 1 arcsecond in a little less than 2 minutes of time.
Click here for a full-page printable chart in PDF format showing Vesta's path through the "fixed" stars in 2010.
Posted by Alan MacRobert, December 31, 2009
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Good Clear Skies
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Astrocomet
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Colin James Watling
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Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
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Web: http://lyra.freewebsites.com/
--
Good Clear Skies
--
Astrocomet
--
Colin James Watling
--
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
--
Web: http://lyra.freewebsites.com/
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