Featured Research

from universities, journals, and other organizations

Blurring the lines between stars and planets: Lonely planets offer clues to star formation

Date:
October 9, 2013
Source:
Max Planck Institute for Astronomy/Max-Planck-Institut fόr Astronomie
Summary:
Astronomers have captured an image of an unusual free-floating planet. As the object has no host star, it can be observed and examined much easier than planets orbiting stars, promising insight into the details of planetary atmospheres.

Multicolor image from the Pan-STARRS1 telescope of the free-floating planet PSO J318.5-22, in the constellation of Capricornus. The planet is extremely cold and faint, about 100 billion times fainter in optical light than the planet Venus. Most of its energy is emitted at infrared wavelengths. The image is 125 arcseconds on a side.
Credit: N. Metcalfe & Pan-STARRS 1 Science Consortium

Astronomers including Niall Deacon of the Max Planck Institute for Astronomy (MPIA) captured an image of an unusual free-floating planet. As the object has no host star, it can be observed and examined much easier than planets orbiting stars, promising insight into the details of planetary atmospheres. Can an object with as low a mass as this have formed directly, in the same way that stars form? Independent observations by a group led by MPIA's Viki Joergens suggest that this is the case: They discovered that a similar but much younger free-floating object is drawing material from its surrounding just like a young star. This has important consequences for star formation models in general.

Related Articles


Things used to be so simple. On the one hand, there were stars: gigantic incandescent nuclear furnaces, emitting substantial amounts of light. On the other hand, there were planets, with much lower masses than stars, reflecting their host stars' light. Stars formed from the collapse of gigantic clouds of gas; planets formed in disks of gas and dust around their nascent host stars. In between there was the somewhat more ambiguous class of brown dwarfs: an intermediaries between planet and star, more massive than a planet, but with insufficient mass for nuclear fusion to ignite in the object's core, turning it into a star. Now, two new discoveries have blurred the border between these kinds of object even further, as they show that free-floating objects with planet-like masses very likely form like stars.

Using the Pan-STARRS 1 (PS1) telescope on Hawai'i, an international team of astronomers led by Michael Liu from the University of Hawaii has discovered an exotic young object with a mass six times that of the gas giant Jupiter, which is floating in space on its own -- no host star in sight. The object, dubbed PSO J318.5-22, is located just 80 light-years away from Earth, in the constellation Capricornus. Its properties are similar to those of giant gas planets found orbiting around young stars. At an estimated age of 12 million years, it is an adolescent in terms of planetary or stellar ages.

Between 1995 and now, astronomers have found nearly a thousand extrasolar planets -- but mostly by indirect methods, detecting a wobbling or dimming of the host stars induced by the planet. Only a handful of planets have been directly imaged, all of which are around young stars (less than 200 million years old). PSO J318.5-22 is very similar in mass, color, and energy output to those directly imaged planets. Niall Deacon (Max Planck Institute for Astronomy), who is a co-author of the study, explains why this is a stroke of luck for astronomers: "Planets found by direct imaging are incredibly hard to study, since they are right next to their much brighter host stars. PSO J318.5-22 is not orbiting a star so it will be much easier for us to study. It is going to provide a wonderful view into the inner workings of gas-giant planets like Jupiter in an early phase of their evolution."

With just six times the mass of Jupiter, PSO J318.5-22 is one of the lowest-mass free-floating objects known, perhaps the very lowest. Ordinary planets are formed in a disk of gas and dust surrounding the embryo of the star they will eventually orbit. But how do solitary objects like this come into existence? Can objects this low-mass -- free-floating planets and brown dwarfs in general -- form in the same way as ordinary stars? An in-depth study of a different object, published at the same time by another group of astronomers which is led by MPIA's Viki Joergens, provides valuable evidence that they do.

Joergens and her team studied an object called OTS44, which is only about 2 million years old -- in terms of stellar or planetary time-scales a newborn baby. The object has an estimated 12 Jupiter masses (marginally more massive than PSO J318.5-22). It is also floating through space without a close companion -- but in a particularly interesting part of space: OTS44 is a member of the Chamaeleon star forming region in the Southern constellation Chamaeleon, at a little over 500 light-years from Earth, where numerous new stars are born from the collapse of dense clouds of gas and dust.

Just like a young star, OTS44 is surrounded by a disk of gas and dust. And, as Joergens and colleagues were able to show, the birth of this object isn't quite over yet: the astronomers split the light of OTS44 into its component colors using the SINFONI spectrograph at ESO's Very Large Telescope in Chile, discovering features that indicate OTS44 is still drawing in material from its disk at a substantial rate. Joergens explains: "Our observations show that, even now, there is still gas falling onto OTS44, increasing its mass."

Furthermore, combining data from numerous telescopes, including the Herschel Space Observatory, and carefully constructing a model of the free-floating planet, Joergens and her colleagues were able to show that the disk surrounding OTS44, traces of which had been found earlier, is quite substantial, with at least 30 times the mass of Earth. Both the substantial disk and the infalling material (accretion) are telltale signs of the standard mode of star formation -- an indication that there is no fundamental difference between the formation of a low-mass objects such as OTS44 and an ordinary star. OTS44 probably has the lowest mass of all objects where disk and infalling material have been detected.

Joergens continues: "If PSO J318.5-22 is an adolescent object, OTS44 is a newborn baby -- and we can see that it has been born just like an ordinary star. For the researchers working on star formation, knowing that the same processes are at work all the way down to planetary-mass objects is key information."

Such objects do not fall clearly into any of the existing categories. Solitary planets or extremely low-mass brown dwarfs -- if you want to play it safe, you can talk, more generally, about free-floating planetary-mass objects. Hubert Klahr (MPIA), an expert in simulations of star and planet formation, who was not involved in the research, comments: "This is another indication that our traditional categories of planets and stars, which are based on mass values, tell us nothing about the inner structure or the formation history of these objects."


Story Source:

The above story is based on materials provided by Max Planck Institute for Astronomy/Max-Planck-Institut fόr Astronomie. Note: Materials may be edited for content and length.


Journal Reference:

  1. Michael C. Liu, Eugene A. Magnier, Niall R. Deacon, Katelyn N. Allers, Trent J. Dupuy, Michael C. Kotson, Kimberly M. Aller, W. S. Burgett, K. C. Chambers, P. W. Draper, K. W. Hodapp, R. Jedicke, R.-P. Kudritzki, N. Metcalfe, J. S. Morgan, N. Kaiser, P. A. Price, J. L. Tonry, R. J. Wainscoat. The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating Planetary-Mass Analog to Directly Imaged Young Gas-Giant Planets. Astrophysical Journal Letters, 2013; (in press) [link]

Cite This Page:

Max Planck Institute for Astronomy/Max-Planck-Institut fόr Astronomie. "Blurring the lines between stars and planets: Lonely planets offer clues to star formation." ScienceDaily. ScienceDaily, 9 October 2013. <www.sciencedaily.com/releases/2013/10/131009152944.htm>.
Max Planck Institute for Astronomy/Max-Planck-Institut fόr Astronomie. (2013, October 9). Blurring the lines between stars and planets: Lonely planets offer clues to star formation. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2013/10/131009152944.htm
Max Planck Institute for Astronomy/Max-Planck-Institut fόr Astronomie. "Blurring the lines between stars and planets: Lonely planets offer clues to star formation." ScienceDaily. www.sciencedaily.com/releases/2013/10/131009152944.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Space & Time News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Spokesman: 'NORAD Ready to Track Santa'

Spokesman: 'NORAD Ready to Track Santa'

AP (Dec. 19, 2014) — Pentagon spokesman Rear Adm. John Kirby said that NORAD is ready to track Santa Claus as he delivers gifts next week. Speaking tongue-in-cheek, he said if Santa drops anything off his sleigh, "we've got destroyers out there to pick them up." (Dec. 19) Video provided by AP
Powered by NewsLook.com
NASA's Planet-Finding Kepler Mission Isn't Over After All

NASA's Planet-Finding Kepler Mission Isn't Over After All

Newsy (Dec. 18, 2014) — More than a year after NASA declared the Kepler spacecraft broken beyond repair, scientists have figured out how to continue getting useful data. Video provided by Newsy
Powered by NewsLook.com
Rover Finds More Clues About Possible Life On Mars

Rover Finds More Clues About Possible Life On Mars

Newsy (Dec. 17, 2014) — NASA's Curiosity rover detected methane on Mars and organic compounds on the surface, but it doesn't quite prove there was life ... yet. Video provided by Newsy
Powered by NewsLook.com
Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Evidence of Life on Mars? NASA Rover Finds Methane, Organic Chemicals

Reuters - US Online Video (Dec. 16, 2014) — NASA's Mars Curiosity rover finds methane in the Martian atmosphere and organic chemicals in the planet's soil, the latest hint that Mars was once suitable for microbial life. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

More Coverage


A Strange Lonely Planet Found Without a Star

Oct. 9, 2013 — An international team of astronomers has discovered an exotic young planet that is not orbiting a star. This free-floating planet, dubbed PSO J318.5-22, is just 80 light-years away from Earth and has ... read more

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins