Featured Research

from universities, journals, and other organizations

Dusty disc of crushed comets around a nearby star caused by collisions with thousands of comets a day

Date:
April 12, 2012
Source:
UK Space Agency
Summary:
Astronomers have studied a ring of dust around the nearby star Fomalhaut and have deduced that it is created by the collision of thousands of comets every day.

Comparison of the Fomalhaut system with our own Solar System. This illustration shows the size of the debris disc observed around the star Fomalhaut, as compared to the size of the Kuiper Belt and Asteroid Belt in the Solar System. The upper image shows the star Fomalhaut surrounded by its debris disc, which is located at a radius of about 130 astronomical units (AU) from the star. A candidate planet, Fomalhaut b, detected around the star in 2008, is also indicated; this detection is, however, still under debate. The central image shows the outer Solar System, with the Kuiper Belt, a rich reservoir of icy objects located beyond the orbit of Neptune and thought to be the source of short-period comets. The Kuiper Belt extends from 30 to 50 AU from the Sun. The lower image shows the inner Solar System, including the asteroid belt, which is located between the orbits of Mars and Jupiter and extends from roughly 2 to 4 AU from the Sun.
Credit: NASA/ESA/STScI

Astronomers Herschel have studied a ring of dust around the nearby star Fomalhaut and have deduced that it is created by the collision of thousands of comets every day.

Related Articles


Fomalhaut, a star twice as massive as our Sun and around 25 light years away, has been of keen interest to astronomers for many years. With an age of only a few hundred million years it is a fairly young star, and in the 1980s was shown to be surrounded by relatively large amounts of dust by the IRAS infrared satellite. Now Herschel, with its unprecedented resolution, has produced the best ever far-infrared images of the system. The star itself is surrounded by hot gas and dust, and there is a warm, dusty disc surrounding it as well. But the most interesting feature is a belt of dusty material on the outer edges of the system.

The belt of dust is relatively far from the star itself, at more than 100 times the distance of Earth from the Sun. This makes it very cold, at around -200 Celsius, with around half of it being made of water ice. "This disc is similar to the Kuiper Belt in our Solar System, which lies beyond the planet Neptune, but is much, much younger," explained Dr Bruce Sibthorpe, of the UK Astronomy Technology Centre. "As well as relatively large objects, such as Pluto, our Kuiper Belt also contains millions of much smaller objects."

The dusty belt around Fomalhaut is confined into a fairly narrow ring and is also off-centre relative to the star, both of which imply that there could be planets orbiting close to it. In 2008 the Hubble Space Telescope provided possible evidence for a planet orbiting within it -- though that has yet to be confirmed.

The way that the dust absorbs, emits and scatters the starlight can be used to deduce the size of the grains. The infrared observations with Herschel have found that the dust absorbs light as if it were made of very small grains, just a few thousandths of a millimetre across. Meanwhile the Hubble Space Telescope images indicate that it scatters light in the same way as much larger particles. These two properties are satisfied if the dust grains are "fluffy," being made of small particles loosely stuck together to make larger ones.

A significant problem with such fluffy grains is that the smaller ones should be blown out of the system by the intense light from Fomalhaut itself. The fact that they are present implies that there is a continuous supply of small particles, most likely produced bythe continual collisions and disintegration of larger asteroid-sized objects. Such a ring would contain many icy comets, but to produce the amount of dust seen by Herschel requires the equivalent of around 2000 1km sized comets to be destroyed every day.

"I was really surprised," says Dr Bram Acke, at the University of Leuven, Belgium, who led this study. "To me this was an extremely large number." Such a large number of collisions implies that there are trillions of comets in the ring in total, containing enough material to make over one hundred Earths.

"Herschel is the only facility with the capability to study the small dust grains in such high detail, and thereby provide important insights into the on-going activity within the Fomalhaut disc," says Dr Sibthorpe. "These studies are showing us a young Extra-Solar System in unprecedented detail."


Story Source:

The above story is based on materials provided by UK Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

UK Space Agency. "Dusty disc of crushed comets around a nearby star caused by collisions with thousands of comets a day." ScienceDaily. ScienceDaily, 12 April 2012. <www.sciencedaily.com/releases/2012/04/120412105704.htm>.
UK Space Agency. (2012, April 12). Dusty disc of crushed comets around a nearby star caused by collisions with thousands of comets a day. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2012/04/120412105704.htm
UK Space Agency. "Dusty disc of crushed comets around a nearby star caused by collisions with thousands of comets a day." ScienceDaily. www.sciencedaily.com/releases/2012/04/120412105704.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Space & Time News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Spokesman: 'NORAD Ready to Track Santa'

Spokesman: 'NORAD Ready to Track Santa'

AP (Dec. 19, 2014) Pentagon spokesman Rear Adm. John Kirby said that NORAD is ready to track Santa Claus as he delivers gifts next week. Speaking tongue-in-cheek, he said if Santa drops anything off his sleigh, "we've got destroyers out there to pick them up." (Dec. 19) Video provided by AP
Powered by NewsLook.com
NASA's Planet-Finding Kepler Mission Isn't Over After All

NASA's Planet-Finding Kepler Mission Isn't Over After All

Newsy (Dec. 18, 2014) More than a year after NASA declared the Kepler spacecraft broken beyond repair, scientists have figured out how to continue getting useful data. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Reuters - US Online Video (Dec. 16, 2014) NASA's Mars Curiosity rover finds methane in the Martian atmosphere and organic chemicals in the planet's soil, the latest hint that Mars was once suitable for microbial life. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins