Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Exocomets may be as common as exoplanets

08.01.2013
Comets trailing wispy tails across the night sky are a beautiful byproduct of our solar system’s formation, icy leftovers from 4.6 billion years ago when the planets coalesced from rocky rubble.
The discovery by astronomers at the University of California, Berkeley, and Clarion University in Pennsylvania of six likely comets around distant stars suggests that comets – dubbed “exocomets” – are just as common in other stellar systems with planets.

Artistic depiction of dust and comets around the young star Beta Pictoris as seen from the outer edge of its disk. NASA image by Lynette Cook.

Though only one of the 10 stars now thought to harbor comets is known to harbor planets, the fact that all these stars have massive surrounding disks of gas and dust ‑ a signature of exoplanets – makes it highly likely they all do, said Barry Welsh, a research astronomer at UC Berkeley’s Space Sciences Laboratory.

“This is sort of the missing link in current planetary formation studies,” Welsh said. “We see dust disks – presumably the primordial planet-forming material – around a whole load of stars, and we see planets, but we don’t see much of the stuff in between: the asteroid-like planetesimals and the comets. Now, I think we have nailed it. These exocomets are more common and easier to detect than people previously thought.”

Welsh will present the findings on Monday, Jan. 7, during a meeting of the American Astronomical Society in Long Beach, Calif. Three of the new exocomets were reported in the Oct. 2012 issue of the journal Publications of the Astronomical Society of the Pacific by Welsh and colleague Sharon L. Montgomery of the Department of Physics at Clarion University.

Welsh also will participate in a media briefing on Tuesday, Jan. 8, at 2:30 p.m. PST in Room 204 on Level 2 of the Long Beach Convention Center.

Welsh summarized the current theory of planet formation as “interstellar dust under the influence of gravity becomes blobs, and the blobs grow into rocks, the rocks coalesce and become bigger things – planetesimals and comets – and finally, you get planets.”

Many stars are known to be surrounded by disks of gas and dust, and one of the closest, beta-Pictoris (â-Pic), was reported to have comets in 1987. In 2009, astronomers found a large planet around â-Pic about 10 times larger than Jupiter. Three other stars – one discovered by Welsh in 1998 – were subsequently found to have comets.

“But then, people just lost interest. They decided that exocomets were a done deal, and everybody switched to the more exciting thing, exoplanets,” Welsh said. “But I came back to it last year and thought, ‘Four exocomets is not all that many compared to the couple of thousand exoplanets known – perhaps I can improve on that.’”

Detecting comets may sound difficult – after all, the snowballs are typically only 5-20 kilometers (3-13 miles) in diameter. But Welsh said that once comets are knocked out of their parking orbit in the outer reaches of a stellar system and fall toward a star, they heat up and evaporate. The evaporating comet, which is what we see with comets such as Halley and next year’s highly anticipated Comet ISON, creates a brief, telltale absorption line in the spectrum of a star.

The six new exocomet systems were discovered during three five-night-long observing runs between May 2010 and November 2012 using the 2.1-meter telescope of the McDonald Observatory in Texas. The telescope’s high resolution spectrograph revealed weak absorption features that were found to vary from night to night, an outcome that Welsh and Montgomery attributed to large clouds of gas emanating from the nuclei of comets as they neared their central stars.

All of the newly discovered exocomets – 49 Ceti (HD 9672), 5 Vulpeculae (HD 182919), 2 Andromedae, HD 21620, HD 42111 and HD 110411 – are around very young type A stars, which are about 5 million years old, because Welsh’s detection technique works best with them. With a higher resolution spectrograph, he might be able to detect comets around the older and yellower G and F stars around which most exoplanets have been found.

Nevertheless, all evidence suggests that these dusty A stars should have planets, and planets are the only thing that could knock a comet out of its orbit and make it fall toward its star.

“If it quacks, waddles and has feathers, then it’s probably a duck,” he said.

The work was supported by the National Aeronautics and Space Administration.

RELATED INFORMATION
UC Berkeley astronomers find comets around two nearby stars, indicating the likelihood of planets forming (June 11, 1998 press release)

Robert Sanders | EurekAlert!
Further information:
http://www.berkeley.edu

Further reports about: Astronomical Beach COMET Clarion Exocomets Space gas and dust nearby star

More articles from Physics and Astronomy:

nachricht The sleeping giant
12.02.2016 | ESA/Hubble Information Centre

nachricht Scientists take nanoparticle snapshots
11.02.2016 | DOE/Argonne National Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Production of an AIDS vaccine in algae

Today, plants and microorganisms are heavily used for the production of medicinal products. The production of biopharmaceuticals in plants, also referred to as “Molecular Pharming”, represents a continuously growing field of plant biotechnology. Preferred host organisms include yeast and crop plants, such as maize and potato – plants with high demands. With the help of a special algal strain, the research team of Prof. Ralph Bock at the Max Planck Institute of Molecular Plant Physiology in Potsdam strives to develop a more efficient and resource-saving system for the production of medicines and vaccines. They tested its practicality by synthesizing a component of a potential AIDS vaccine.

The use of plants and microorganisms to produce pharmaceuticals is nothing new. In 1982, bacteria were genetically modified to produce human insulin, a drug...

Im Focus: The most accurate optical single-ion clock worldwide

Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock which attains an accuracy which had only been predicted theoretically so far. Their optical ytterbium clock achieved a relative systematic measurement uncertainty of 3 E-18. The results have been published in the current issue of the scientific journal "Physical Review Letters".

Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock...

Im Focus: Goodbye ground control: autonomous nanosatellites

The University of Würzburg has two new space projects in the pipeline which are concerned with the observation of planets and autonomous fault correction aboard satellites. The German Federal Ministry of Economic Affairs and Energy funds the projects with around 1.6 million euros.

Detecting tornadoes that sweep across Mars. Discovering meteors that fall to Earth. Investigating strange lightning that flashes from Earth's atmosphere into...

Im Focus: Flow phenomena on solid surfaces: Physicists highlight key role played by boundary layer velocity

Physicists from Saarland University and the ESPCI in Paris have shown how liquids on solid surfaces can be made to slide over the surface a bit like a bobsleigh on ice. The key is to apply a coating at the boundary between the liquid and the surface that induces the liquid to slip. This results in an increase in the average flow velocity of the liquid and its throughput. This was demonstrated by studying the behaviour of droplets on surfaces with different coatings as they evolved into the equilibrium state. The results could prove useful in optimizing industrial processes, such as the extrusion of plastics.

The study has been published in the respected academic journal PNAS (Proceedings of the National Academy of Sciences of the United States of America).

Im Focus: New study: How stable is the West Antarctic Ice Sheet?

Exceeding critical temperature limits in the Southern Ocean may cause the collapse of ice sheets and a sharp rise in sea levels

A future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Symposium on Climate Change Adaptation in Africa 2016

12.02.2016 | Event News

Travel grants available: Meet the world’s most proficient mathematicians and computer scientists

09.02.2016 | Event News

AKL’16: Experience Laser Technology Live in Europe´s Largest Laser Application Center!

02.02.2016 | Event News

 
Latest News

Graphene leans on glass to advance electronics

12.02.2016 | Materials Sciences

Twisting magnets enhance data storage capacity

12.02.2016 | Materials Sciences

A metal that behaves like water

12.02.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>