. 24/7 Space News .
STELLAR CHEMISTRY
The end of a star or a supernova impostor
by Staff Writers
Granada, Spain (SPX) Mar 15, 2017


A violent eruption such as SN 2015bh could be a way to fast-track the star's evolution to its last phase. If SN 2015bh and other events with similar pattern have survived this explosion, they could already be on their way to become Wolf-Rayet stars.

Massive stars end their lives in supernova explosions, highly energetic events that can be as luminous as the entire starlight from their host galaxies. However, there are events called "supernova impostors" which, despite their intensity, are not the end of the star's life. This could very well be the case of SN 2015bh, a star which had suffered at least 21 years of violent eruptions and which, together with a number of other objects, could be a member of a new class.

"Luminous blue variable stars like this one show two different kinds of eruptions: regular outbursts after which the star returns to its original state and giant eruptions which alter the star permanently. A prominent example is Eta Carinae, a star which has already lost mass equivalent to 40 times the mass of our Sun though winds and eruptions", says Christina Thone, scientist at the Institute for Astrophysics of Andalucia (IAA-CSIC) and head of the HETH group (High energy transients and their hosts) who is leading the study.

Some stars suffer even larger outbursts that very much resemble real supernova explosions. The dividing line between those imposter supernovae and real ones is still a matter of debate. The case of SN 2015bh is a good example for this difficult decision about whether the explosion has ended the life of the star or not.

The Turbulent Chronology Of Sn 2015Bh
Archival records show that the star had experienced frequent minor eruptions since at least 1994, alternating with quieter periods. On Feb. 10, 2015, an outburst was detected and classified as impostor supernova, which prompted a renewed interest in the star.

In April 2015 a group lead by the Institute of Astrophysics of Andalucia (IAA-CSIC) started weekly observations from different observatories observing this new outburst that started to decay slowly. This later called "precursor event" was followed by an even more intense outburst on May 16 which, instead of declining, was rising in intensity until May 24. The energy released in this so-called "main event" is compatible with the release in a real supernova.

"The vast majority of data were obtained from Spanish telescopes, in particular from the Calar Alto observatory in Almeria, the Gran Telescopio Canarias on La Palma and the Observatory of Sierra Nevada (Granada). In fact, the main event had been detected thanks to the Observatory of Sierra Nevada", says Christina Thone (IAA-CSIC).

Subsequent observations spanning up to 200 days after the main event, show that the star has lost luminosity, and now shows bluer colors than in previous phases, but are unable to confirm that the star has exploded. In addition, the entire process turns out to be very similar to a few other events for which the death of the star could not be confirmed either until now.

"Now we know already several cases of these luminous blue variables that follow the same pattern: smaller, more or less continuous eruption over several decades and an outburst between 40 and 80 days before the main explosion. In fact, the evolution of SN 2015bh turns out to be basically a carbon copy of SN 2009ip, a famous example of a supernova impostor that took place in 2012 whose fate is still highly debated", explains Christina Thone (IAA-CSIC).

On A Fast Track To The Wolf-Rayet Phase
In the current theoretical framework, luminous blue variables are massive stars in a transition to a Wolf-Rayet phase, which is supposed to be the last phase of its life. But before they can enter this phase, they have to get rid of their outer envelope and the mechanism for that is still unknown: the stars can lose their envelope though very strong stellar winds, however, these winds might result being very inefficient to achieve the transition to the Wolf-Rayet phase; a single giant eruption does not seem to solve the problem either, as we see in Eta Carinae, which has already suffered at least two giant eruptions and still continues as a luminous blue variable star.

Nevertheless, a violent eruption such as SN 2015bh could be a way to fast-track the star's evolution to its last phase. If SN 2015bh and other events with similar pattern have survived this explosion, they could already be on their way to become Wolf-Rayet stars.

"SN 2015bh is not an isolated case and there are possibly many more similar objects out there that have gone unnoticed, but it seems we have encountered a new type of stellar event. Now we need to uncover the mechanism driving those events and find out why the observed cases show such very similar behavior", Christina Thone (IAA-CSIC) concludes.

C. Thone et al. "SN2015bh: NGC2770's 4th supernova or a luminous blue variable on its way to a Wolf-Rayet star?" Astronomy and Astrophysics, Volume 599 (March 2017)

STELLAR CHEMISTRY
Star clusters discovery could upset the astronomical applecart
Perth, Australia (SPX) Mar 07, 2017
The discovery of young stars in old star clusters could send scientists back to the drawing board for one of the Universe's most common objects. Dr Bi-Qing For, from the International Centre for Radio Astronomy Research in Perth, said our understanding of how stars evolve is a cornerstone of astronomical science. "There are a billion trillion stars in the Universe and we've been observing ... read more

Related Links
Instituto de Astrofisica de Andalucia
Stellar Chemistry, The Universe And All Within It


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


Comment on this article using your Disqus, Facebook, Google or Twitter login.

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

STELLAR CHEMISTRY
Visions of the Future: Planetary Exploration Through 2050

Campaign Tests Parachutes Designed to Provide Astronauts a Soft Landing

Keeping Liquids Off the Wall

International space docking standard updated

STELLAR CHEMISTRY
Kennedy's Multi-User Spaceport Streamlines Commercial Launches

Designing new rocket engines that don't blow up

Space squadron supports record-breaking satellites launch

Europe launches fourth Earth monitoring satellite

STELLAR CHEMISTRY
Opportunity Driving South to Gully

Mars Rover Tests Driving, Drilling and Detecting Life in Chile's High Desert

NASA Mars Orbiter Tracks Back-to-Back Regional Storms

Paleolake deposits on Mars might look like sediments in Indonesia

STELLAR CHEMISTRY
China Develops Spaceship Capable of Moon Landing

Long March-7 Y2 ready for launch of China's first cargo spacecraft

China Seeks Space Rockets Launched from Airplanes

Riding an asteroid: China's next space goal

STELLAR CHEMISTRY
UK funding space entrepreneurs

Kymeta and Intelsat announce new service to revolutionize how satellite services are purchased

ISRO Makes More Space for Private Sector Participation in Satellite Making

Kuwait Space Agency - a pipedream or reality

STELLAR CHEMISTRY
MIPT physicists predict the existence of unusual optical composites

Orbiting in sunshine

New application of the selective laser melting method

Scientists develop new surface finishing for 3D-printing

STELLAR CHEMISTRY
Light From An Ultra-Cool Neighbor

Could fast radio bursts be powering alien probes

Enzyme-free krebs cycle may have been key step in origin of life on Earth

Kepler Provides Another Peek at Ultra-cool Neighbor

STELLAR CHEMISTRY
NASA Mission Named 'Europa Clipper'

Juno Captures Jupiter Cloudscape in High Resolution

Juno to remain in current orbit at Jupiter

Europa Flyby Mission Moves into Design Phase









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.