Nav: Home

Old stars live longer than we thought

February 25, 2019

Towards the end of their lives some 95% of stars evolve into red giants which lose their mass via a "stellar wind". Eventually they end up as planetary nebulae, ionized gas with a central hot star, a white dwarf.

Researchers form 14 European scientific institutions, among them the IAC, have detected the existence of a binary interaction which had not been noticed by the scientific community. This new research offers an alternative explanation to the high rates of mass loss which it was thought were present towards the end of the lives of the most massive giant stars.

The study, which is published today in the journal Nature Astronomy, show that these stars lose mass at a much slower rate than previously thought. The stellar wind is not stronger than usual, but it is affected by a companion star which had not been noticed until now, a second star orbiting around the red giant. The fact that this process is slower than expected has a major impact on our understanding of how stars end their lives. As a consequence of this discovery we find that the most massive giant star need a longer time to expel their chemically rich interiors into their environment, which affects the enrichment of the interstellar medium, and therefore the chemical evolution of galaxies.

The only observatory which could provide detailed information about the disconcerting superwind in the last phase of the lives of the most massive stars is ALMA (Atacama Large Millimetre/Submillimetre Array), in the Atacama desert (Chile)."The data show a spiral structure which show that these stars are not individual have a binary companion" explains Anibal García Hernández, a researcher at the IAC and at the ULL, a co-author of the article. He adds "The interaction with its companion gives rise to a rather complex morphology, in the form of an incomplete spiral. Previous data lacked the spatial resolution and the sensitivity given by ALMA and did not allow astronomers to find the characteristics associated with a binary star"

The interpretation of the ALMA observations has shown in a convincing way that the last evolutionary phase of these old stars is not characterized by a short-lived "extreme superwind" but rather by a "normal wind" which lasts much longer. In other words "old stars take longer to die" or as a slogan "old stars live longer".

Now the scientific community will see if the existence of a binary companion could explain the behaviour of other particular red giants. "We thought that many stars lived alone, but we will probably have to change our ideas" explains Leen Decin, the first author on the article, who is a Professor at the Catholic University of Louvain. She concludes "It is probable that a star with a binary companion is more common than we had thought".
-end-
Scientific article: L. Decin, W. Homan, T. Danilovich, A. de Koter, D. Engels, L. B. F. M. Waters, S. Muller, C. Gielen, D. A. García-Hernández, R. J. Stancliffe, M. Van de Sande, G. Molenberghs, F. Kerschbaum, A. A. Zijlstra and I. El Mellah. 'Reduction of the maximum mass-loss rate of OH/IR stars due to unnoticed binary interaction', Nature Astronomy. DOI: 10.1038/s41550-019-0703-5

Instituto de Astrofísica de Canarias (IAC)

Related Stars Articles:

And then there was light: looking for the first stars in the Universe
Astronomers are closing in on a signal that has been travelling across the Universe for 12 billion years, bringing them nearer to understanding the life and death of the very earliest stars.
Massive stars grow same way as light stars, just bigger
Astronomers obtained the first detailed face-on view of a gaseous disk feeding the growth of a massive baby star.
Our history in the stars
Astronomers map the substance aluminum monoxide (AlO) in a cloud around a distant young star -- Origin Source I.
Stars exploding as supernovae lose their mass to companion stars during their lives
Stars over eight times more massive than the sun end their lives in supernovae explosions.
Old stars live longer than we thought
The type of stars we refer to, which cannot be seen by the naked eye, officially up to now the objects which have suffered the greatest loss of mass.
A nearby river of stars
Astronomy & Astrophysics publishes the work of researchers from the University of Vienna, who have found a river of stars, a stellar stream in astronomical parlance, covering most of the southern sky.
Merging neutron stars
The option to measure the gravitational waves of two merging neutron stars has offered the chance to answer some of the fundamental questions about the structure of matter.
Bubbles of brand new stars
This dazzling region of newly forming stars in the Large Magellanic Cloud (LMC) was captured by the Multi Unit Spectroscopic Explorer instrument (MUSE) on ESO's Very Large Telescope.
Stars shrouded in iron dust
The Instituto de Astrofísica de Canarias (IAC) has participated in a study which has discovered a group of stars very poor in metals and shrouded in a high fraction of iron dust, situated in the Large Magellanic Cloud.
Falling stars hold clue for understanding dying stars
An international team of researchers has proposed a new method to investigate the inner workings of supernovae explosions.
More Stars News and Stars Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.