Strange New Planet Discovered

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hummingbird69

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<b>Strange New Planet Baffles Astronomers</b> <br /><br />Washington, DC - Using a network of small automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta. <br /><br />"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery. <br /><br />With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter. <br /><br />This new discovery suggests something could be missing in our theories of how planets form." <br /><br />Any thoughts on this?<br /><br />New Planet Discovery
 
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MeteorWayne

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Well it certainly is not the largest extra-solar "planet"<br />There are many larger, AFAIK.<br /><br />I'll look at the link, but such a glaring error (It could just be the reporting) makes me wonder. <br /><br />It appears to be a good story, but I still need to understand the discrepency. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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search

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They give some possible explanations at the bottom of the article.<br /><br />Read about another giant extra solar planet with similar carachteristics: Osiris
 
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MeteorWayne

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And maybe I'm wrong, too. I can't remember everything <img src="/images/icons/smile.gif" /><br />A lot lot of what we know of extrasolar planets is estimated. It's the uncertainty principal. If you know the mass, you don't know the orbit or the diameter..It's fun to have so much available speculation as we get this early glimpse into other stars.<br /><br />We learn every day. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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MeteorWayne

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Yeah, but that site only lists masses, not radii.<br />Thanx for the site!<br />There are several dozen more massive than jupiter.<br />The claim I had the problem with was that this object, less massive than jupiter was the largest in radius ever discovered.<br /><br />More digging required.<br /><br />Diameter can only be measured with eclipsed planets, a very small portion of the known extrasolars.<br /><br />The statement might be technically correct, but misleading.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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doubletruncation

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<font color="yellow">Well it certainly is not the largest extra-solar "planet"</font><br /><br />It is the largest one for which we have actually determined a radius (and by far the lowest density one). There are now 12 planets known to transit their host star (including HAT P-1b and Tres-2 b), for which a radius measurement is possible. You can see more details in their preprint at:<br />http://xxx.lanl.gov/abs/astro-ph/0609369<br /><br />In particular Figure 6 shows the masses and radii for 11 of the transiting planets (they didn't know about tres-2 when they wrote the paper) as well as jupiter and saturn. You can see that HAT P-1 b and HD209458-b are two low density planets, the figure doesn't really show it but these are two planets for which models cannot reproduce the masses/radii, HAT P-1 b is even more at odds with models than HD209458-b. The paper gives a good discussion of why this is very interesting.<br /><br />We do know of many other planets that are larger in mass (these include many of the nearly two hundred planets for which we only have doppler velocity measurements and hence only minimum masses). However, for all but the transiting cases, we have no idea what their radii are. If they follow the models, they would all have radii smaller than HAT P-1 b (note that HAT P-1 b actually has a larger radius than small M-dwarf stars). <div class="Discussion_UserSignature"> </div>
 
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hummingbird69

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Search<br /><br />Thanks for the link. What a sight that would be in a computer similation , with the transit star motion.
 
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vogon13

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Maybe the planet has rings and that is throwing off the diameter estimate.<br /><br /><br />-or-<br /><br /><br />It is really a tight orbit binary object.<br /><br /><br /><br />Weird either way (if either).<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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doubletruncation

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If it were rings I think it would have to be tipped on its axis substantially to throw off the radius estimate by that much (being tipped on its axis like Uranus would actually be a possible explanation in its own right).<br /><br />The other star in the binary is very well separated (it's a visual double star), so I don't think it would be pumping its eccentricity. Another planet in the system might be (they can't rule out 0 eccentricity for this planet). <div class="Discussion_UserSignature"> </div>
 
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hummingbird69

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doubletruncation<br /><br />I still don't see how they can rule out the planet not being tipped.<br /><br />Have they explained why Uranus is tipped and why it still has a circular orbit as other planets?
 
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doubletruncation

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I don't think you can rule it out. We know at least for the case of HD 209458 that the angle between the star's spin axis and the planet's orbital axis is only 4 degrees, so that gives credence to the whole nebular collapse scenario - and you would expect then that the rotation axis should be aligned as well barring some collision. But, as you mention, Uranus is tipped while still having a circular orbit that lies in the ecliptic plane. My understanding is that its assumed some collision did take place in the case of Uranus - I don't know though if there has been an explanation that also satisfies the other dynamical constraints from the rest of the solar system. I could only guess that the reason it doesn't seem likely that the hot jupiters would be tipped despite the example of Uranus in our own solar system is that the cross-section for a collision with another massive object would be much lower in the case of the hot jupiters - but I have no idea if that's true or if there is even a strong reason to believe it would be true. <div class="Discussion_UserSignature"> </div>
 
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Good point MW <br /><br />I actually miss that "small little detail" in the article but then went on to find something on the subject (different planet). Read through:<br /><br />Full article:<br />http://www.bu.edu/phpbin/news/releases/display.php?id=1136<br /><br />Summary on subject:<br />“Using data from a telescope in Flagstaff, Arizona that BU operates in partnership with Lowell Observatory, we helped to confirm for Dr. McCullough that XO-1b really is in fact a planet as well as quantify its size,” said Janes. “By looking at how much the star’s brightness decreases as it is blocked by the planet the team was able to determine that XO-1b is somewhat larger in diameter than Jupiter.” <br /><br />Extrasolar planet discovery technics:<br />http://www.star.ucl.ac.uk/~rhdt/diploma/lecture_2/<br /><br />Extrasolar planets project:<br />http://www.novacelestia.com/space_art_extrasolar_planets/mission_extrasolar_planets.html<br />
 
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doubletruncation

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<font color="yellow">This HAT-P-1 is not confirmed anyway</font><br /><br />I don't know what the article is talking about, but this planet certainly is "confirmed." They have radial velocity measurements with Keck HIRES and the Subaru HDS plus good precision light curves of the transits using Keplercam on the FLWO 1.2 m telescope on multiple dates as well as from the Konkoly/Piszkestelo 0.6 m telescope. Analyzing these together they get a mass of 0.53 +- 0.04 jupiter masses, a radius of 1.36 (+0.11, -0.09) jupiter radii and an orbital inclination (with respect to the line of sight) of 85.9 +- 0.8 degrees. They excluded blend scenarios from the lack of variations in the spectral line bisector spans. So I think this is as good a confirmation as you can get for any of these transiting planets (better than can be done for the five faint transiting planets discovered by OGLE). In fact, in some ways it's even better than any of the other planets since it's part of a wide-separated binary system so you can do a simultaneous evolutionary fit to the two stars to obtain a better determination of mass/radius for the star from the photometry/spectroscopy than you could otherwise. You can see their paper, http://xxx.lanl.gov/abs/astro-ph/0609369 for details.<br /><br />It's true that no independent group has obtained data yet, but it will happen quite shortly, and I would be very very surprised, based on the quality of the data in this paper, if it turned out this wasn't a planet. <div class="Discussion_UserSignature"> </div>
 
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Good point<br /><br />Post changed<br /><br />The comment was refering to the Geneva Programme confirmations.
 
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MeteorWayne

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Thanks for that link.<br />Discovery and education continue! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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alokmohan

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Confirmed HAThttp://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2084&mode=thread&order=0&thold=0http://www.aUsing a network of small automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta. <br /><br /> <br />The Hungarian Automated Telescope (HAT) is a small autonomous observatory designed for robotic observations of the night sky without human intervention. <br />Credit: HAT <br /><br />"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery. <br /><br />With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter. <br /><br />"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher." <br /><br />HAT-P-1 revolves around its host star every 4.5 days in an orbit one-twentieth of the distance from Earth to the Sun. Once each orbit, it passes in front of its parent star, causing the star to appear fainter by about 1.5 percent for more than two hours, after which the star returns to its previous brightness. <br /><br />HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated
 
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hummingbird69

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doubletruncation<br /><br />Do you believe this changes the idea of how planets are formed?<br /><br />Its nicked named puffy ? <img src="/images/icons/smile.gif" /><br /><br />
 
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doubletruncation

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I think it means that theories of hot planet formation or of the structure/evolution of hot jupiters are at least incomplete and possibly inaccurate. Until people start coming up with ideas that are consistent with the current observations, I think it's difficult to say what's wrong. <div class="Discussion_UserSignature"> </div>
 
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