. 24/7 Space News .
STELLAR CHEMISTRY
ALMA finds unexpected trove of gas around larger stars
by Staff Writers
Charlottesville VA (SPX) Aug 29, 2016


Artist impression of a debris disk surrounding a star in the Scorpius-Centaurus Association. ALMA discovered that - contrary to expectations - the more massive stars in this region retain considerable stores of carbon monoxide gas. This finding could offer new insights into the timeline for giant planet formation around young stars. Image courtesy NRAO/AUI/NSF; D. Berry / SkyWorks. For a larger version of this image please go here.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) surveyed dozens of young stars - some Sun-like and others approximately double that size - and discovered that the larger variety have surprisingly rich reservoirs of carbon monoxide gas in their debris disks. In contrast, the lower-mass, Sun-like stars have debris disks that are virtually gas-free.

This finding runs counter to astronomers' expectations, which hold that stronger radiation from larger stars should strip away gas from their debris disks faster than the comparatively mild radiation from smaller stars. It may also offer new insights into the timeline for giant planet formation around young stars.

Debris disks are found around stars that have shed their dusty, gas-filled protoplanetary disks and gone on to form planets, asteroids, comets, and other planetesimals. Around younger stars, however, many of these newly formed objects have yet to settle into stately orbits and routinely collide, producing enough rubble to spawn a "second-generation" disk of debris.

"Previous spectroscopic measurements of debris disks revealed that certain ones had an unexpected chemical signature suggesting they had an overabundance of carbon monoxide gas," said Jesse Lieman-Sifry, lead author on a paper published in Astrophysical Journal. At the time of the observations, Lieman-Sifry was an undergraduate astronomy major at Wesleyan University in Middletown, Connecticut. "This discovery was puzzling since astronomers believe that this gas should be long gone by the time we see evidence of a debris disk," he said.

In search of clues as to why certain stars harbor gas-rich disks, Lieman-Sifry and his team surveyed 24 star systems in the Scorpius-Centaurus Association. This loose stellar agglomeration, which lies a few hundred light-years from Earth, contains hundreds of low- and intermediate-mass stars. For reference, astronomers consider our Sun to be a low-mass star.

The astronomers narrowed their search to stars between five and ten million years old - old enough to host full-fledged planetary systems and debris disks - and used ALMA to examine the millimeter-wavelength "glow" from the carbon monoxide in the stars' debris disks.

The team carried out their survey over a total of six nights between December 2013 and December 2014, observing for a mere ten minutes each night. At the time it was conducted, this study constituted the most extensive millimeter-wavelength interferometric survey of stellar debris disks ever achieved.

Armed with an incredibly rich set of observations, the astronomers found the most gas-rich disks ever recorded in a single study. Among their sample of two dozen disks, the researchers spotted three that exhibited strong carbon monoxide emission. Much to their surprise, all three gas-rich disks surrounded stars about twice as massive as the Sun. None of the 16 smaller, Sun-like stars in the sample appeared to have disks with large stores of carbon monoxide.

This finding is counterintuitive because higher-mass stars flood their planetary systems with energetic ultraviolet radiation that should destroy the carbon monoxide gas lingering in their debris disks. This new research reveals, however, that the larger stars are somehow able to either preserve or replenish their carbon monoxide stockpiles.

"We're not sure whether these stars are holding onto reservoirs of gas much longer than expected, or whether there's a sort of 'last gasp' of second-generation gas produced by collisions of comets or evaporation from the icy mantles of dust grains," said Meredith Hughes, an astronomer at Wesleyan University and coauthor of the study.

The existence of this gas may have important implications for planet formation, says Hughes. Carbon monoxide is a major constituent of the atmospheres of giant planets. Its presence in debris disks could mean that other gases, including hydrogen, are present, but perhaps in much lower concentrations. If certain debris disks are able to hold onto appreciable amounts of gas, it might push back astronomers' expected deadline for giant planet formation around young stars, the astronomers speculate.

"Future high-resolution observations of these gas-rich systems may allow astronomers to infer the location of the gas within the disk, which may shed light on the origin of the gas," says co-author Antonio Hales, an astronomer with the Joint ALMA Observatory in Santiago, Chile, and the National Radio Astronomy Observatory in Charlottesville, Virginia.

"For instance, if the gas was produced by planetesimal collisions, it should be more highly concentrated in regions of the disk where those impacts occurred. ALMA is the only instrument capable of making these kind of high-resolution images."

According to Lieman-Sifry, these dusty disks are just as diverse as the planetary systems they accompany. The discovery that the debris disks around some larger stars retain carbon monoxide longer than their Sun-like counterparts may provide insights into the role this gas plays in the development of planetary systems.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
National Radio Astronomy Observatory
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
STELLAR CHEMISTRY
Study: Only larger stars boast gas-rich disks
Middletown, Conn. (UPI) Aug 25, 2016
Recent observations made by Atacama Large Millimeter/submillimeter Array, ALMA, suggest larger stars host significant carbon monoxide gas reservoirs. ALMA astronomers were surprised by the finding. The larger the star, researchers hypothesized, the more likely radiation could have burned away any accumulated gas. When scientists looked at the debris disks surrounding 24 star syst ... read more


STELLAR CHEMISTRY
Space tourists eye $150mln Soyuz lunar flyby

Roscosmos to spend $7.5Mln studying issues of manned lunar missions

Lockheed Martin, NASA Ink Deal for SkyFire Infrared Lunar Discovery Satellite

As dry as the moon

STELLAR CHEMISTRY
Anomalous grooves on Martian moon Phobos explained by impacts

NASA Awards Launch Services Contract for Mars 2020 Rover Mission

Year-long simulation of humans living on Mars ends in Hawaii

Boredom was hardest part of yearlong dome isolation

STELLAR CHEMISTRY
The Deep Space Network

Grandpa astronaut breaks US space record

35 years later Voyager's legacy continues at Saturn

Chinese sci-fi prepares to master the universe

STELLAR CHEMISTRY
China Sends Country's Largest Carrier Rocket to Launch Base

'Heavenly Palace': China to Launch Two Manned Space Missions This Fall

China unveils Mars probe, rover for ambitious 2020 mission

China Ends Preparatory Work on Long March 5 Next-Generation Rocket Engine

STELLAR CHEMISTRY
US astronauts complete spacewalk for ISS maintenance

Space Station's orbit adjusted Wednesday

Astronauts Relaxing Before Pair of Spaceships Leave

'New port of call' installed at space station

STELLAR CHEMISTRY
Galileo's Ariane 5 arrives at Europe's Spaceport

Vega's multi-satellite payload integration begins for Arianespace Flight VV07

SpaceX's Dragon cargo ship splashes down in Pacific

Sky Muster II comes to French Guiana for launch on Ariane 5

STELLAR CHEMISTRY
Discovery one-ups Tatooine, finds twin stars hosting three giant exoplanets

Could Proxima Centauri b Really Be Habitable

Rocky planet found orbiting habitable zone of nearest star

A new Goldilocks for habitable planets

STELLAR CHEMISTRY
New optical material offers unprecedented control of light and thermal radiation

Copernicus Sentinel-1A satellite hit by space particle

Northrop Grumman gets $375 million G/ATOR radar contract

UNIST to engineer next-generation smart separator membranes









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.