Category Archives: extrasolar planets

astronomy news, extrasolar planets, Gemini Observatory

First Picture of a Planet around a Sun-like Star

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Gemini Observatory Image Shows Possible Extrasolar Planet

1RSX J160929.1-210524 and its likely ~8 Jupiter-mass companion (in red circle)
1RSX J160929.1-210524 and its likely ~8 Jupiter-mass companion (in red circle) The suspected planet 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). Its likely host is a young star of type K7 with an estimated mass about 85% that of the Sun.

So, there I was on Friday night, playing with a computer game when I got a call from the Public Information Office at Gemini Observatory. I do some editing and writing for them from time to time, and since they’re six hours behind me (time-zone-wise) a late Friday call is not exactly a surprise. But, what Peter Michaud (their PIO) told me next was big news: that Gemini had likely bagged the first known image of a planet orbiting another star similar to the Sun. Not only that, but it is a HUGE planet (8 Jupiter masses) and orbits more than three hundred times the Earth-Sun distance from its own parent star.

This, as you might expect if you follow extrasolar planet searches, is big news. Nobody has directly imaged an actual planet around a normal star like the Sun before. Stars are too bright and planets are usually too small to be seen in the glare of the nearby star.  So far, planet discoveries have been made using several indirect methods, such as the Doppler detection technique (which measures the Doppler shift in starlight that occurs as a star and its planet(s) orbit around a common center of mass) about which you can read more here.

So, as you can imagine, an actual image of an extrasolar planet is pretty exciting; so much so that when the team of astronomers at the University of Toronto that did the work posted a pre-print paper about their finding, people took immediate notice. Gemini Observatory then worked up a press release (that a number of us then finessed over the weekend) and it came out early today. I expect this news will generate a lot of excitement and discussion in planetary-search circles.

The suspected star-planet combo (which lies about 500 light-years from Earth) was found as part of a survey of over 85 stars in the Upper Scorpius association, a group of young stars formed about 5 million years ago.

“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 submitted to the Astrophysical Journal Letters and also posted online. “If we confirm that this object is indeed gravitationally tied to the star, it will be a major step forward.”

The near-infrared images and spectra of this suspected planetary object indicate that it is too cool to be a star or even a more massive brown dwarf, and that it is very young. Spectra indicate that it is the same distance from Earth as its star. It will probably take the better part of two years to absolutely confirm that this planet is definitely orbiting that star, but the science team making the discovery points to this data as very compelling evidence to prove that it is.

The team’s Gemini observations took advantage of adaptive optics technology to dramatically reduce distortions caused by turbulence in Earth’s atmosphere so they could make out the object, which appears to be orbiting its primary star at a distance of about 330 astronomical units.  To put this in comparison to our own solar system, Neptune orbits the Sun at about 40 AU, Pluto is at 39.4 AU.

exoplanets, extrasolar planets, planetary science

They’re Having the Vapors!!

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Some Protoplanetary Disks have Water Vapor

Image:M42proplyds.jpgSo, not only have astronomers found methane in the atmosphere of a planet circling another star, but now CalTech astronomers have found water vapor in the spinning disks of gas and dust surrounding other stars. These disks, called protoplanetary disks, or “proplyds” for short, are where planets are born.

The Earth and other planets of the solar system formed in a proplyd beginning more than 4.5 billion years ago, and so we look to other systems to understand how planets are born, and how ours looked at that time. The image here is a protoplanetary disk in the Orion Nebula studied by Hubble Space Telescope.

The astronomers used NASA’s Spitzer Space Telescope and the Keck II telescope on Mauna Kea in Hawai’i to study the infrared wavelengths of light emitted by from these disks. The chemical fingerprints of water vapor showed up in disks around the stars DR Tau and AS 205A. The next step was to figure out where the vapor exists in the disk around each star. So, the science team (consisting of astronomers from CalTech, the Leiden Observatory in the Netherlands, SRON, and the University of Texas at Austin) made high-resolution measurements at shorter wavelengths of infrared light. The data showed the clumps of material where the water resides were moving at fast speeds, meaning that the clumps are closer to their stars, possibly in regions where Earth-like planets might be forming.

Now, you might think, “Okay, so they’ve found water vapor at a couple of stars. So what?” Astronomers expect to make more observations of dozens of similar-type stars, and the two instruments they’ve used should turn up more water vapor in more proplyds (if it exists). The bigger implications lie with figuring out how water concentrations evolve and survive in protoplanetary disks and eventually create oceans (or ice-covered planets). Who knows? What scientists find may help us understand how Earth got its oceans. Stay tuned!