Tag Archive: Astronomer


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Phys.org

Comet Catalina grows two tails, soars at dawn

November 23, 2015 by Bob King, Universe Today
Comet C/2013 US10 Catalina shows off a compact green coma and two tails in this photo taken this morning (Nov. 22, 2015) at dawn from Arizona. The green color comes from carbon compounds fluorescing in UV sunlight. Credit: Chris Schur

Amateur astronomer Chris Schur of Arizona had only five minutes to observe and photograph Comet Catalina this morning before twilight got the better of the night. In that brief time, he secured two beautiful images and made a quick observation through his 80mm refractor. He writes:

“Very difficult observation on this one. (I observed) it visually with the 35mm Panoptic ocular. It was a round, slightly condensed object with no sign of the twin tails that show up in the images. After five minutes, we lost it visually as it was 2° degrees up in bright twilight. Images show it for a longer time and a beautiful emerald green head with two tails forming a Y shaped fan.”

North is up and east to the left in these two photos of the comet made by Dr. D.T. Durig at 6:23 a.m. EST on Nov. 21st from Cordell-Lorenz Observatory in Sewanee, Tenn. He estimated the coma diameter at ~2 arc minutes with a tail at least …

Read more at: http://phys.org/news/2015-11-comet-catalina-tails-soars-dawn.html#jCp

Schur estimated the comet’s brightness at around magnitude +6. What appears to be the dust extends to the lower right (southeast) with a narrower ion tail pointing north. With its twin tails, I’m reminded of a soaring eagle or perhaps a turkey vulture rocking back and forth on its wings. While they scavenge for food, Catalina soaks up sunlight.

I also headed out before dawn for a look. After a failed attempt to spot the new visitor on Saturday, I headed down to the Lake Superior shoreline at 5:30 a.m. today and waited until the comet rose above the murk. Using 7×50 binoculars in a similar narrow observing window, I could barely detect it as a small, fuzzy spot 2.5° south of 4th magnitude Lambda Virginis at 5:50 a.m. 10 minutes after the start of astronomical twilight. The camera did better!

 

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STELLAR CHEMISTRY

by Marcus Woo for Caltech News
Pasadena CA (SPX)


This image, taken with NASA’s Spitzer infrared space telescope, shows the mysterious galactic cloud, seen as the black object on the left. The galactic center is the bright spot on the right. Credit: NASA/Spitzer/Benjamin et al., Churchwell et al.

It’s the mystery of the curiously dense cloud. And astronomers at the California Institute of Technology (Caltech) are on the case. Near the crowded galactic center, where billowing clouds of gas and dust cloak a supermassive black hole three million times as massive as the sun-a black hole whose gravity is strong enough to grip stars that are whipping around it at thousands of kilometers per second-one particular cloud has baffled astronomers.

Indeed, the cloud, dubbed G0.253+0.016, defies the rules of star formation.

In infrared images of the galactic center, the cloud-which is 30 light-years long-appears as a bean-shaped silhouette against a bright backdrop of dust and gas glowing in infrared light. The cloud’s darkness means it is dense enough to block light.

According to conventional wisdom, clouds of gas that are this dense should clump up to create pockets of even denser material that collapse due to their own gravity and eventually form stars.

One such gaseous region famed for its prodigious star formation is the Orion Nebula. And yet, although the galactic-center cloud is 25 times denser than Orion, only a few stars are being born there-and even then, they are small. In fact, the Caltech astronomers say, its star-formation rate is 45 times lower than what astronomers might expect from such a dense cloud.

“It’s a very dense cloud and it doesn’t form any massive stars-which is very weird,” says Jens Kauffmann, a senior postdoctoral scholar at Caltech.

In a series of new observations, Kauffmann, along with Caltech postdoctoral scholar Thushara Pillai and Qizhou Zhang of the Harvard-Smithsonian Center for Astrophysics, have discovered why: not only does it lack the necessary clumps of denser gas, but the cloud itself is swirling so fast that it can’t settle down to collapse into stars.

The results, which show that star formation may be more complex than previously thought and that the presence of dense gas does not automatically imply a region where such formation occurs, may help astronomers better understand the process.

 

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