First Picture of Likely Planet Around a Sun-Like Star


Astronomers have unveiled what is likely the first picture of a planet around a normal star similar to the Sun. Using the Gemini North telescope on Mauna Kea in Hawaii, astronomers from the University of Toronto imaged the young star 1RXS J160929.1-210524, which lies about 500 light-years from Earth and a candidate companion of that star. They also obtained spectra to confirm the nature of the companion, which has a mass about eight times that of Jupiter, and lies roughly 330 times the Earth-Sun distance away from its star. For comparison, the most distant planet in our solar system, Neptune, orbits the Sun at only about 30 times the Earth-Sun distance. The parent star is similar in mass to the Sun, but is much younger. “This is the first time we have directly seen a planetary mass object in a likely orbit around a star like our Sun,” said David Lafrenière, lead author of a paper detailing the discovery. “If we confirm that this object is indeed gravitationally tied to the star, it will be a major step forward.”

Until now, the only planet-like bodies that have been directly imaged outside of the solar system are either free-floating in space (i.e. not found around a star), or orbit brown dwarfs, which are dim and make it easier to detect planetary-mass companions.

The existence of a planetary-mass companion so far from its parent star comes as a surprise, and poses a challenge to theoretical models of star and planet formation. “This discovery is yet another reminder of the truly remarkable diversity of worlds out there, and it’s a strong hint that nature may have more than one mechanism for producing planetary mass companions to normal stars,” said team member Ray Jayawardhana.

The team’s Gemini observations took advantage of adaptive optics technology to dramatically reduce distortions caused by turbulence in Earth’s atmosphere. The near-infrared images and spectra of the suspected planetary object indicate that it is too cool to be a star or even a more massive brown dwarf, and that it is young.

While it could be a chance alignment between the object and the young star, it will take up to two years to verify that the star and its likely planet are moving through space together. “Of course it would be premature to say that the object is definitely orbiting this star, but the evidence is extremely compelling. This will be a very intensely studied object for the next few years!” said Lafrenière.

Team member Marten van Kerkwijk described the group’s search method. “We targeted young stars so that any planetary mass object they hosted would not have had time to cool, and thus would still be relatively bright,” he said. “This is one reason we were able to see it at all.”

The Jupiter-sized body has an estimated temperature of about 1800 Kelvin (about 1500ºC), much hotter than our own Jupiter, which has a temperature of about 160 Kelvin (-110ºC), and its likely host is a young star of type K7 with an estimated mass of about 85% that of the Sun.

“This discovery certainly has us looking forward to what other surprises nature has in stock for us,” said Van Kerkwijk.

Read the team’s paper here.

Source: Gemini Observatory

24 Replies to “First Picture of Likely Planet Around a Sun-Like Star”

  1. Excellent work. The article doesn’t emphasize it, but it was very clever to look for young hot objects still radiating strongly in the infrared.

    Nice going, folks!

  2. Very impressive work indeed…
    More questions follow this discovery…Looks like we have to be in the drawing board for a few more yrs to get a comprehensive idea about the formation of planetary systems…

  3. that’s pretty amazing. it’s hard to believe that that planet is 330 AU from its sun. from our POV it ‘looks’ much closer.

    again, the vastness of a galaxy, and by extension the universe, is amazing and impossible to comprehend. but fun to try!

  4. Indeed amazing, albeit yet to be fully confirmed.

    It does raise interesting questions about the formation of such objects, particularly the fact that it’s so hot compared to its distance from the star.

  5. Looks like we can expect another class of hot Jupiters: far from the host star and young.

    Then we do not have one observation bias, but two!

  6. justin, the imaging was in the near infrared, so the 1800K (2,780 deg. F) is bright in IR. Of course, the K7 star (~ 3800K) is hotter and brighter. [This image is in false color, so don’t let that confuse you.]

  7. Oh, I meant to add that this massive planet is hot because of its own heat and not due to the star’s radiation upon it, no doubt.

  8. justin Says:
    September 15th, 2008 at 4:09 pm

    “hi, i dont know much about anything, but how can it be 330AU and so hot?”

    >>>I think this passage from the article answers your question justin –

    “Team member Marten van Kerkwijk described the group’s search method. “We targeted young stars so that any planetary mass object they hosted would not have had time to cool, and thus would still be relatively bright,” he said. “This is one reason we were able to see it at all.”

    Basically, as it is a young stellar system, any planetary objects in the system will have only recently coalesced. This process adds a huge amount of energy to a growing planet, and so this is how it derives its heat.

  9. # LLDIAZ Says:
    September 15th, 2008 at 11:49 am

    “Did I miss something or are there any reasons this isn’t just a lucky shot.”

    >>>This is from the arxiv paper:

    “Although our photometry and spectroscopy establish that the candidate companion has low gravity and a mass in the planetary regime, they do not prove that it is physically bound to the primary star rather than a free-floating planet in the association. A recent census of the Upper Scorpius association (Carpenter et al. 2006) reported 340 members with masses above 0.1 M⊙ over a 150 deg2 area of the sky. Assuming
    conservatively that there are as many free-floating planets in the association as there are stars > 0.1 M⊙, the probability that one would fall within 2.5′′ from any of the 82 stars we have observed would be only 3×10-4. Thus this scenario is highly unlikely. Proper-motion confirmation of physical association will nevertheless be very important, and should be feasible within the next few years.”

  10. Wow! First ever direct image of an exosolar planet around a sun like star! I can’t believe this isn’t all over the news on tv,

  11. Jupiter gives off more energy (as heat radiation) than it recieves from the sun…. so I’m not suprised that a planet with a mass of 8 jupiters is hot – regardless of its distance from its parent star.

    Whether this is due to slow cooling, or from some internal power source I don’t know. (could the energy be coming from radioactive decay?)

  12. Nice shot!
    If that turns out to be a planet, I wonder how a large, distant object such as this affects the evolution of other planets in this system….

    help or hurt?

  13. If:
    we have an extremely bright light source (giant star or even supernovae), but somehow succeeds in blocking the light from the source itself.
    Perhaps then astronomers would be able to detect much more of the “dark environment” of that source, even to a great distance, so we get a more accurate picture of what is betweeen stars – even small dark objects?

  14. Vladimir

    We are seeing radiation from the planet – not reflected light – so no phases. If the planet were to be illuminated from the parent star – I suspect the phase would still be invisible given the technology we have at present

  15. Wow, over 30 billion miles away? That’s surprisingly far from the star. I read about a similar planet that that has a mass 12 times that of Jupiter and also orbits it’s star from 30+ billion miles away. But what’s more surprising about that planet with it’s great distance from it’s star is that the star is a red dwarf 1/3 the mass of the Sun. On a larger scale like the Sun, the planet would orbit not 30 billion miles, but 100 billion miles from it’s star. And the planet would be 40 times the mass of Jupiter.

    Now another news, this time about a brown dwarf, not a planet, but still amazing. The brown dwarf orbits not a burning star, but a collapsed star- a white dwarf. The most amazing thing is how close the brown dwarf orbits the star and the orbital period. The brown dwarf orbits the star from 2/3 the radius of the Sun! That’s only 288,000 miles. Almost like the Moon’s distance from the Earth. The brown dwarf orbits the star once every 2 hours. 12 times per Earth day; 3,000 times every Venus day. At 500,000 miles an hour! At a speed like that, a 5 minute space trip around the Earth from 288,000 miles would be nice.

    Another, not new discovery is of a binary star system of 2 white dwarfs. If 288,000 miles apart is a tight system, these white dwarfs orbit each other only 50,000 miles apart! Their orbital periods are 24 times shorter than the previous. They orbit each other once every 5 minutes! 288+ times an Earth day; 70,000+ times every Venus day. 3,800,000+ miles an hour; 1,100+ miles a second! But there is a pulsar that spins 300,000 times every time those 2 white dwarfs orbit each other. Or 1,000+ times a second. 86,400,000+ times an Earth day; 21,000,000,000+ times a Venus day!

    Go to the web I posted if you would like to listen to the sounds of the Pulsars. They mentioned 1 pulsar that you can’t listen to the sound, because it was discovered years after the web was made. But they never mentioned the 1/1000 second pulsar, which was discovered years later.

  16. I am pretty much sure that this is a brown dwarf ,planets can not be that big and hot ,you will get deuterium fusion if you go this large,jupiter is the ideal exaple of how big a planet can be.

    I know i am right.

  17. The planetary candidate orbiting the K7V star 1RXS J160929.1-210524 is posted at arXiv:0809.1424. Spectroscopy & direct imaging suggest an 8 Jupiter mass object( type L4 ) orbiting this young low-mass star in the upper Scorpius association. Spectra suggest a temp of ~1800 K , but this might be expected of a young(hot) planetary-mass object. I’m familiar with earlier claims of planetary mass objects (which have mostly been inconclusive or just in error). These authors caution that further observations are needed to determine if this object is actually orbiting this star (or may possibly be a free-floating planet) but the evidence they present seems pretty interesting. I’d be interested to see what subsequent observations of this candidate planet may reveal.

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