New look at HD 10180 shows it might have nine planets

[ScienceRocks]

New look at HD 10180 shows it might have nine planets
April 9, 2012 by Bob Yirka
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HD 10180 planetary system (Artist's Impression). Image: ESO/L. Calçada
New look at HD 10180 shows it might have nine planets
(Phys.org) -- Astronomer Mikko Tuomi of the University of Hertfordshire, has found after looking at data regarding the solar system surrounding the star HD 10180, that it likely has nine planets making it the most highly populated solar system known to man (ours has just eight after the demotion of Pluto). He details his findings in a paper pre-published on arXiv (and set for publication in Astronomy and Astrophysics) describing how after studying slight wobbles by the star as it’s tugged by planetary gravitation, he found what he believes is confirmation of a seventh planet, and evidence for two more.

HD 10180 is about 130 light years away from us, in the Hydrus constellation and was first noted by astronomers in 2010. At the time it was thought the solar system consisted of just five planets, though there was speculation that it might have as many as seven. Since that time, other work has shown that there are likely six planets, five of which are believed to have a mass close to that of Neptune. The other appears closer in mass to Saturn. Researchers come to these conclusions by studying the way a star appears to wobble (a Doppler shift) as it responds to the gravitational pull of planets orbiting around it. By studying these light shifts, astronomers can deduce not only the size of the planet that causes it, but its period as well. Those originally noted had periods ranging from 5 to 2000 days.

Tuomi didn’t make any new observations, instead he went back and looked at the original data using different kinds of statistical analysis techniques. In so doing, he found evidence for three more planets, all much smaller than the original six. These new planets, which he estimates to be 1.3, 1.9, and 5.1 times the size of Earth, have much shorter periods (1.2, 10 and 68 days) than the other planets indicating that they are very close to their star, closer even than Mercury is to our sun, which would mean they are far too hot to support water retention or life, at least as we know it.

It’s important to note that such work doesn’t actually prove that any of the planets suspected of revolving around HD 10180 actually exist, it merely offers strong evidence. Adding even more is statistical evidence offered by Tuomi suggesting that if there are truly planets there, they all appear to have stable orbits.

 

[whitehall]

It could have planets with oceans and birds but it don't mean a thing when it's 700 trillion miles away give or take a million miles.

 

[Old Rocks]

Really? New knowledge means nothing? Oh well, consider the source.

 

[American Horse]

"Nine planets" has the ring of familiarity which adds to its attractiveness for us, but the arrangement is all wrong. This is but another data-point in our collection. Fact is These are just refinements in our methods of finding new planets around distant suns.

Recently three planets, the smallest to date, were discovered around red dwarf star KOI-961. The planets are 0.78, 0.73, and 0.57 times earth's radius, and all are rocky worlds, and all are close-in to the parent star, and that proximity is what makes their detection so easy, and likely to become more and more common.

All three planets are thought to be rocky like Earth but orbit close to their star, making them too hot to be in the habitable zone, which is the region where liquid water could exist. Of the more than 700 planets confirmed to orbit other stars, called exoplanets, only a handful are known to be rocky.

"Astronomers are just beginning to confirm the thousands of planet candidates uncovered by Kepler so far," said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Finding one as small as Mars is amazing, and hints that there may be a bounty of rocky planets all around us."

A planet the size of Earth out at the same distance ( One A.U.) is exceedingly hard to find against the backdrop of the brilliant light (note that KOI-961 is q red dwarf) from its star. And the relative size difference of about a 10,000 mile radius to a sun's 1,000,000 mile radius is so great that no wobble is produced, and the size of the planet is tiny by comparison. A small planet orbiting in just a few days or hours transits its sun often enough to catch the attention of an observer. But the further out the longer the wait for that incidence, and alignment is everthing.

But the abundance of planets makes for lots of discoveries even though they require near perfect conditions to be seen but new equipment like the Kepler Space Observatory, three years in orbit now, continues to make the difference.