Uncovering the birthplaces of stars in the Milky Way

An international team of scientists led by Ivan Minchev of the Leibniz Institute for Astrophysics Potsdam (AIP) has found a way to recover the birthplaces of stars in our galaxy. This is one of the major goals in the field of galactic archaeology, whose aim is to reconstruct the formation history of the Milky Way.

Stars in galactic discs have long been known to wander away from their birth sites owing to a phenomenon known as "radial migration." This movement across the galaxy severely hampers inferences of the Milky Way formation history.

Radial migration is influenced by a number of parameters that are still poorly known: for example, the size and speed of the galactic bar, the number and shape of spiral arms in the galactic disc, and the frequency of smaller galaxies colliding with the Milky Way during the past 10 billion years and their respective masses.

To circumvent these obstacles, the scientists devised a way of recovering the galactic migration history using the ages and chemical composition of stars as "archaeological artifacts."

They used the well-established fact that star formation in the galactic disc progresses gradually outwards, following that stars born at a given position at a particular time have a distinct chemical-abundance pattern.

Therefore, if the age and chemical composition (its iron content, for example) of a star can be measured very precisely, it becomes possible to directly infer its birth position in the galactic disc without additional modeling assumptions.

The team used a sample of about 600 solar-neighborhood stars observed with the high-resolution spectrograph HARPS mounted on the 3.6 m telescope of ESO's La Silla Observatory in Chile. Thanks to the very precise age and iron abundance measurements, it was found that these stars were born all across the galactic disc, with older ones coming more from the central parts.

Researches can now use this method for calculation of birthplaces even for stars not in the original sample. For example, given the age of our Sun of 4.6 billion years and its iron content, it could be estimated that the Sun was born about 2,000 light-years closer to the galactic center than it is currently located.

Minchev comments: "Once in the possession of birth radii, a wealth of invaluable information could be gained about the Milky Way past, even from this small number of stars with precise enough measurements available to us at this time."

Co-author Friedrich Anders adds: "In the near future, applying this method to the extremely high-quality data from the Gaia mission and ground-based spectroscopic surveys will allow much more exact measurements of the migration history and, thus, the Milky Way past."

Research Report: "Estimating Stellar Birth Radii and the Time Evolution of the Milky Way's ISM Metallicity Gradient," I. Minchev et al., 2018 Aug. 1, Monthly Notices of the Royal Astronomical Society

Related Links
Leibniz Institute For Astrophysics
Stellar Chemistry, The Universe And All Within It

Tweet

Thanks for being there;
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 Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

Magnetized Inflow Accreting to Center of Milky Way
Hilo HI (SPX) Aug 20, 2018
Is magnetic field an important guiding force for gas accreting to supermassive black hole (SMBH) - for example, the one that our Milky Way Galaxy hosts? The role of magnetic field in this subject is little understood and trying to observe it has been challenging to astronomers. Researchers at the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Taiwan, led by Dr. Pei-Ying Hsieh, have obtained a good measurement by using the instruments on the James Clerk Maxwell Telescope (JCMT). T ... read more