Starship Asterisk*

HD 10180: Richest Yet Planetary System Discovered

Explanation: Do other rich planetary systems exist? Our Solar System has the most planets of any known star, most probably because it is so hard to detect planets around other stars. Sensitive measurements, though, have now uncovered a slight but complex wobble of the Sun-like star HD 10180 indicating that it has at leave five planets and possibly more, making it the richest extra-solar planetary system yet known. HD 10180's planets were discovered in years of data using the sensitive HARPS spectrograph attached to the ESO's 3.6-meter telescope in La Silla, Chile. The planetary system appears quite different than our Solar System, since all of HD 10180's discovered planets have Neptune-like masses but orbit inside the distance of Mars. An artist's depiction of flying into this system is shown in the above video. In the future, more sensitive data taken over longer time periods may extend the star-wobble detection technique into the realm of uncovering more distant and more Earth-like planets.

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Very interesting for a number of reasons.

One reason is that this discovery brings home that we still know so little about other planetary systems. This is because it is so incredibly difficult to detect small, dark, light-weight planets as they cosy up right next to brilliant stars. Available techniques are being pushed to the limit to find more planets, and small rocky planets like the Earth are much, much harder to detect than planets the size and mass of Jupiter or even Neptune.

Another important point that is being emphasized by this discovery is that small rocky planets are not rare. We have no reason at all to think that rocky planets are hard to form. They are difficult to detect, but undoubtedly they exist in incredible numbers out there.

A third, very important point that needs to be made is that just because a planet is "Earth-sized" it isn't automatically "Earth-like". In fact, this discovery brings home once again that our Solar system is not "typical". The distance of the planets from our G-type Sun, their spacing and almost circular orbits here have so far not been matched by any other solar system that astronomers have detected. The solar system that is being described in today's APOD is different from our own in that the planets are lined up much closer to their sun than in our own solar system. As far as I can understand, there is no planet in this other solar system where water could be liquid, unless, of course, one of the Neptune-like planets which orbit at a more suitable distance from its sun has a moon with an atmosphere.

My conclusion is that there are myriads of solar system out there and huge numbers of planets, Earth-sized and otherwise, but for all of that the Goldilocks kind of planet where all the conditions for life are "just right" might nevertheless be exceedingly rare.

Ann

Beautiful!

In my humble opinion, the ultimate astronomical experience would be to tag along with ... daily visits to 18000 planets (within 3 hours!). ... Can you imagine visiting each planet for approximately 1/2 a second each?

Yeshurun

This needs correction:

"...slight but complex wobble of the Sun-like star HD 10180 indicating that it has at leave five planets..."

at least five...

It is 127 light-years away.....so who cares...........

Plenary, a. [LL. plenarius, fr. L. plenus full. See Plenty.] Full; entire; complete; absolute
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Plethora, n. [NL., fr. Gr. , fr. to be or become full.]

1. Overfullness; especially, excessive fullness of the blood vessels; repletion.
2. State of being overfull; excess; superabundance.

In time we will be able to detect smaller and smaller planets; but it is very difficult. Look how hard it has been detecting the the small orbs in our own system out in the Oort and Kuiper areas. I believe Earth like and Earth size planets are out there. Whether we can detect them or not!
I wonder how hard it would be to detect Earth around Sol from one of these distant systems. I imagine that with equipment like ours that the four giant planets in our system would be all that would be found.

There must be some very complicated math involved in figuring out the approximate masses of the 5+ planets just from the wobble of the star. That's pretty crazy.

Guest wrote:There must be some very complicated math involved in figuring out the approximate masses of the 5+ planets just from the wobble of the star. That's pretty crazy.

It's not as bad as you might expect. A fairly simple method called Fourier analysis (or a variant) is used to decompose a complex looking signal (in this case, as a function of time) into constituent sine waves (or similar functions) of differing amplitude and period. Once you have those, conventional Keplerian analysis can provide information about the orbital dynamics and body masses.

I don't mean to trivialize a lot of the finesse in the whole analysis, just point out that fundamentally, what is done, is pretty straightforward (and could have been done more than 100 years ago, given the data).

neufer wrote:Plenary, a. [LL. plenarius, fr. L. plenus full. See Plenty.] Full; entire; complete; absolute
..................................................
Plethora, n. [NL., fr. Gr. , fr. to be or become full.]

1. Overfullness; especially, excessive fullness of the blood vessels; repletion.
2. State of being overfull; excess; superabundance.

http://en.wiktionary.org/wiki/plethora

1.An excessive amount or number; an abundance.
2.An excess of red blood cells or bodily humours.

The collection of astronomical images on the APOD web page, is most plethoric than any other.

Many grettings
Cesar