Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Exocomets may be as common as exoplanets

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.

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:

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

More articles from Physics and Astronomy:

nachricht New method will enable most accurate neutron measurement yet
02.10.2015 | Paul Scherrer Institut (PSI)

nachricht An easier way to operate and program multitasking machines
30.09.2015 | Siemens AG

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: New Sinumerik features improve productivity and precision

EMO 2015, Hall 3, Booth E06/F03

  • Drive optimization called automatically by the part program boosts productivity
  • Automatically switching the dynamic values to rapid traverse and interpolation...

Im Focus: LZH presents additive manufacturing at the LABVOLUTION

The Laser Zentrum Hannover e.V. (LZH) will present how laser-based technologies can contribute to the laboratory of the future at the LABVOLUTION in Hannover in Hall 9, Stand E67/09, from October 6th to 8th, 2015. As a part of the model lab smartLAB, the LZH is showing how additive manufacturing, better known as 3-D printing, can make experimental setups more flexible.

Twelve partners from science and industry are presenting an intelligent and innovative model lab at the special display smartLAB. A part of this intelligent...

Im Focus: New polymer creates safer fuels

Before embarking on a transcontinental journey, jet airplanes fill up with tens of thousands of gallons of fuel. In the event of a crash, such large quantities of fuel increase the severity of an explosion upon impact.

Researchers at Caltech and JPL have discovered a polymeric fuel additive that can reduce the intensity of postimpact explosions that occur during accidents and...

Im Focus: 3-D printing techniques help surgeons carve new ears

When surgical residents need to practice a complicated procedure to fashion a new ear for children without one, they typically get a bar of soap, carrot or an apple.

To treat children with a missing or under-developed ear, experienced surgeons harvest pieces of rib cartilage from the child and carve them into the framework...

Im Focus: Walk the line

NASA studies physical performance after spaceflight

Walking an obstacle course on Earth is relatively easy. Walking an obstacle course on Earth after being in space for six months is not quite as simple. The...

All Focus news of the innovation-report >>>



Event News

EHFG 2015: Securing healthcare and sustainably strengthening healthcare systems

01.10.2015 | Event News

Conference in Brussels: Tracking and Tracing the Smallest Marine Life Forms

30.09.2015 | Event News

World Alzheimer`s Day – Professor Willnow: Clearer Insights into the Development of the Disease

17.09.2015 | Event News

Latest News

Infrared thermography can detect joint inflammation and help improving work ergonomics

02.10.2015 | Medical Engineering

Semiconductor nanoparticles show high luminescence in a polymer matrix

02.10.2015 | Materials Sciences

New Sinumerik features improve productivity and precision

02.10.2015 | Trade Fair News

More VideoLinks >>>