Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

An exoplanet from another galaxy

19.11.2010
Astronomers have discovered the first exoplanet that originated in another galaxy. The planet's host star belongs to a dwarf galaxy which was swallowed up by our home galaxy, the Milky Way, billions of years ago. Remarkably, the Jupiter-like planet orbits a star nearing the end of its life. It appears to have survived the star's "Red giant" stage, which offers a tantalizing glimpse of one possible fate of our own Solar System in the distance future. The results are being published on November 18 in Science Express.

Over the last 15 years, astronomers have detected nearly 500 exoplanets orbiting ordinary stars in our cosmic neighborhood. Now, for the first time, astronomers have detected an exoplanet whose origin appears to lie outside our own galaxy.


An exoplanet from another galaxy (right) and its star (left): Artist\'s impression of the yellowish star HIP 13044 and, on the bottom right, its planet HIP 13044 b. HIP 13044 is part of a stellar stream, a remnant of a dwarf galaxy that was swallowed by the Milky Way galaxy billions of years ago. Credit: ESO/L. Calçada

The planet, which has been designated HIP 13044 b, has a minimum mass of 1.25 times the mass of Jupiter. The star system is located about 2000 light-years from Earth in the southern constellation Fornax ("the chemical furnace").

The planet was discovered with the radial velocity method, which measures tiny wobbles of a star caused by a planet's gravitational pull. HIP 13044's wobbles were detected with the high-resolution spectrograph FEROS at the 2.2 m MPG/ESO telescope at ESO's La Silla observatory in Chile.

The planet and its host star appear to have originated in a dwarf galaxy that was swallowed by the Milky Way galaxy between six and nine billion years ago. Such galactic cannibalism is an ordinary occurrence in galactic evolution. Typically, remnants of swallowed-up dwarf galaxies can be detected as ribbon-like arrangements of stars known as "stellar streams". In this case, HIP 13044 is part of the so-called "Helmi stream".

"This is an exciting discovery," says Rainer Klement of the Max Planck Institute for Astronomy (MPIA), who was responsible for the selection of the target stars for this study. "For the first time, astronomers have detected a planetary system in a stellar stream of extragalactic origin. Because of the great distances involved, there are no confirmed detections of planets in other galaxies. But this cosmic merger has brought an extragalactic planet within our reach."[1]

The newly discovered system has a number of unusual properties. "We found HIP 13044 b as part of a systematic search for exoplanets around stars that are nearing the end of their life," says MPIA's Johny Setiawan, who led the research. While the host star HIP 13044 was probably rather similar to our own Sun earlier on, it has since gone through the "Red Giant" phase, in which a star cools and expands to hundreds of times the radius of the Sun. It has now settled down into another quiet phase powered by the nuclear fusion of Helium, which is expected to last a few million years in total.

The fact that the exoplanet survived the red giant stage provides an intriguing glimpse of one possible fate of our own planetary system: our Sun is expected to become a Red Giant in around five billion years. Setiawan and his colleagues hypothesize that HIP 13044 b's current close orbit – its present average distance to its host star amounts to a mere 12 per cent of the distance between the Sun and the Earth, with an orbital period of only 16.2 days – was initially much larger, and that the planet migrated inwards during the star's Red Giant phase.

There is some evidence that some closer-in planets did likewise, and did not survive: "HIP 13044 is rotating relatively quickly for a star of this particular type," says Setiawan. "One explanation is that HIP 13044 swallowed its inner planets during the Red Giant phase, which would make the star spin more quickly." HIP 13044 b's survival might be in jeopardy, though. In the next stage of its evolution, the star is headed for renewed expansion, and may engulf the planet.

With only this single data point, it is impossible to tell how common this particular evolution is. More definite conclusions – and an understanding of how much HIP 13044 tells us about our own planetary system's future –will only be possible once significantly more planets orbiting similar stars – stars that have reached the later stages of stellar evolution - have been found. This is the aim of an ongoing search by Setiawan and his colleagues.

One final puzzle is that the new planet's host star HIP 13044 appears to contain very few elements heavier than hydrogen and helium (in technical terms, it is "extremely metal-poor") – fewer than any other star with planets. "It is a puzzle for the widely accepted model of planet formation how such a star, which contains hardly any heavy elements at all, could have formed a planet," adds Setiawan.

Contact information

Dr. Johny Setiawan (Lead author)
Max Planck Institute for Astronomy
Phone: (+49|0) 6221 – 528 326
E-mail: setiawan@mpia.de
Dr. Markus Pössel (Public relations)
Max Planck Institute for Astronomy
Phone: (+49|0) 6221 – 528 261
E-mail: pr@mpia.de
Background information
The work described in this release is slated for publication in the journal Science. An electronic version will be published in advance on November 18, 2010 in Science Express as Setiawan et al., "A Giant Planet Around a Metal-poor Star of Extragalactic Origin". The members of the team are Johny Setiawan, Rainer J. Klement, Thomas Henning, Hans-Walter Rix, Boyke Rochau and Tim Schulze-Hartung (all from the Max Planck Institute for Astronomy) and Jens Rodmann (European Space Agency).

Endnote

[1] Because of the great distances involved, current telescopes are not nearly powerful enough to systematically observe exoplanets in other galaxies. There have been tentative claims of the detection of extragalactic exoplanets through "gravitational microlensing" events: During such events, a star A passing in front of an even more distant star B leads to a subtle, but detectable "flash". Some features of that flash indicate that the star A is accompanied by a planet. However, this method relies singular events – the chance alignment of a distant light source, planetary system, and observers on Earth – making it inherently unlikely that such a detection of an extragalactic planet can ever be confirmed.

Dr. Markus Pössel | Max-Planck-Institut
Further information:
http://www.eso.org/public/news/eso1045/
http://www.mpia.de

More articles from Physics and Astronomy:

nachricht MEMS chips get metatlenses
21.02.2018 | American Institute of Physics

nachricht International team publishes roadmap to enhance radioresistance for space colonization
21.02.2018 | Biogerontology Research Foundation

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>