Trio of Super-Earths Discovered

FiReaNGeL writes "A group of astronomers have now discovered a system of three super-Earths around a rather normal star, which is slightly less massive than our Sun, and is located 42 light-years away towards the southern Doradus and Pictor constellations. 'We have made very precise measurements of the velocity of the star HD 40307 over the last five years, which clearly reveal the presence of three planets.' The planets, having 4.2, 6.7, and 9.4 times the mass of the Earth, orbit the star with periods of 4.3, 9.6, and 20.4 days, respectively. 'The perturbations induced by the planets are really tiny — the mass of the smallest planets is one hundred thousand times smaller than that of the star — and only the high sensitivity of HARPS made it possible to detect them' says co-author François Bouchy, from the Institut d'Astrophysique de Paris, France. Clearly these planets are only the tip of the iceberg."

So...we found...?

[oahazmatt (868057)]

Trio of Super-Earths Discovered

So we found more oil?

Re:So...we found...?

[alxkit (941262)]

first we have to make sure that oil-producing GE microbes exist there

Re:

[BunnyClaws (753889)]

No, we won't drill for oil there but we will mine dilithium or latinum.

Re:So...we found...?

[Chris Burke (6130)]

[quote][quote]Trio of Super-Earths Discovered[/quote]

So we found more oil?[/quote]

Not just oil, but Super Oil!

Re:So...we found...?

[Chris Burke (6130)]

[hindsight=20/20]shoulda clicked preview, i say for the hundreth time...[/hindsight]

Re:So...we found...?

[AmiMoJo (196126)]

Isn't Super Earth like... Krypton or something?

Really short periods

[Some guy named Chris (9720)]

Why is it that most of the planets discovered have extremely short orbital periods compared to our own? Is it because those are the easiest types to detect, or is it because we are a cosmic oddity with our slow orbit around our star?

Also, I wonder if one were on one of these planetary speedsters, would you be able to tell you were whizzing around your star so fast.

Re:Really short periods

[Anti_Climax (447121)]

A short orbital period and a higher mass mean a greater possibility we can see the star shifting back and forth as the planet revolves around it. As our instrumentation and measurements get more accurate and precise we should be able to reliably infer the presence of smaller planets with longer orbital periods.

With how many large planets we're finding, it's pretty likely there are plenty of smaller earth like planets to be found when we gain the ability to do so.

Re:Really short periods

[Cinnamon Whirl (979637)]

From TFA: "This star also hosts a Jupiter-like planet with a period close to 3 years"

Not actually the same star as above, but it shows even longer orbital periods can be detected if the planet is large enough.

So, time for a REALLY long-baseline telescope?

[OmniGeek (72743)]

Gee, if we had a telescope array with a baseline of, say, the radius of the Moon's orbit, then we could resolve some REALLY small orbital perturbations, vastly improving our ability to identify planetary systems.

It occurs to me that such a system wouldn't even need to be (continuously) staffed after installation, just the occasional maintenance call.

I think I see an opportunity for a Lunar observatory project...

Re:So, time for a REALLY long-baseline telescope?

[drerwk (695572)]

Two problems with your suggestion. 1) Baseline is not the limit of any planet searches. 2) Planet searches are done with optical frequencies.
You could put a radio telescope on the moon and do VLBI - but not an optical telescope.
The most difficult part right now of detecting planets using Doppler shift is a fixed frequency standard to compare the stars spectrum against - they are measuring centimeter/second movements of the star. Baseline has nothing to do with the current limits. AFAIK, the only optical interferometer of any note is at Keck - and I don't even know if it has been used yet. See this article: http://optics.org/cws/article/research/33693 [optics.org]

Re:So, time for a REALLY long-baseline telescope?

[Aaron Denney (123626)]

Why can't we put an optical telescope on the moon?

Re:

[naoursla (99850)]

There has been plans of creating interferometry telescopes that consist of multiple space craft separated by miles that use magnetic fields to adjust the disance between the spacecraft to focus the telescope.

http://en.wikipedia.org/wiki/Space_Interferometry_Mission [wikipedia.org]

Re:Really short periods

[Glith (7368)]

Because our primary method of detecting a planet right now involves looking at its gravitational effect on the star, and planets that have a lot of mass, are near to their star, and go quickly cause the greatest fluctuation in gravitational force.

Re:

[thesandtiger (819476)]

I would think it's easier to detect by the current methods - seeing transit across the stellar disc, seeing perturbations/wobbles would be easier if they happen more frequently. I bet, if we had the ability to see them directly we'd probably find a few on much longer periods that are less amenable to the transit/wobble detection method.

Or not. I mean, space is really fucking big. Even locally we have a hard time finding things that are "only" a bit further out than pluto...

Re:

[MozeeToby (1163751)]

Short orbital periods are much easier to detect. Most planet hunting activity today is done by watching the parent star for changes in velocity. When a planet is close to the star the changes are both larger and faster, making them much easier to detect.

Re:Really short periods

[oodaloop (1229816)]

One of the ways we detect planets (not sure about the HARPS) is the measurement of the wiggle the parent star makes. The more massive the planet and/or the faster it orbits, the easier it is to detect the wiggle. Basically, the star will move either side to side or back forth from our vantage point (depending on the orientation of the orbit compared to our position), and this slight movement is used to calculate the mass, speed, etc of the orbiting planets. If the planet is orbiting side to side from our veiw point, we measure the speed the star moves side to side. For back and forth, we measure the slight doppler shift in light as it moves towards and away from us. Since closer planets tend to orbit faster, most of the planets we've discovered so far are large, close, fast-moving ones.

Again, this is only one way this is done, and I'm not sure about this particular planet. I can't make heads or tails of the HARPS link in any case.

Re:Really short periods

[by Anonymous Coward]

Whatever you do, don't try to answer this question by typing "really short periods" into Google. Trust me.

Re:Really short periods

[shma (863063)]

As others have mentioned it is a selection bias. Part of this has to do with the detection method. What they do is look at spectral lines from the star to determine how fast it is moving as it 'orbits 'around the center of mass of the star-planet system (this is very close to the center of the star since the star is so massive, so it is more of a wobble than a straight orbit). The closer the planet is to the star, the larger the gravitational force, so the larger the velocity/ doppler shift. So it is easier to find planets with shorter periods. But even if we developed a new technique today that didn't depend on doppler shifts, we would still only find short period planets for the first few years. Why? Because you need to take measurements for at least a full period before you can determine with any accuracy that you're seeing a planet. So planets with 5yr or 10yr periods will not be confirmed right using any new technique, anyways.

And to add to another point made below, it is possible to have a planet with an orbital period measured in days which we could comfortably live on. A white dwarf star would be cold enough to allow for normal temperatures, even at distances closer than Mercury.

Re:

[maynard (3337)]

Here is what JPL says of the about the techniques used to find planets:

http://origins.jpl.nasa.gov/library/exnps/ch04_1.html#4.4 [nasa.gov]

Based upon this I will offer these answers to your questions, though with the caveat that I am not an astronomer.

Astronomers are looking for perturbations in a star's light output intensity or in its lateral movement relative to other known stars.

What does this mean?

If a planet crosses the boundary between the star and us it should dim the light output. If this happens repeatedly a

Re:

[L4t3r4lu5 (1216702)]

Picture a ping-pong ball spinning around a light bulb which is in a shade the size of a football. It orbits the shade once every 5 seconds. You can only see the ping-pong ball when it obscures the light from the shade (oxymoron?), as you're some way away. This means that as long as you look at it for more than 5 seconds, you'll see it twice, and can estimate it'll be there again in another 5 seconds. Testing will confirm this.

Now, imagine that there's a tennis ball orbiting the same shade, but it takes 30

Re:

[RickRussellTX (755670)]

I think your answer is little too glib. If you were standing on such a planet and had no direct way to measure your planet's mass or the local sun's mass, how would you measure the length of a year? Would it be "obvious" that your planet's year was much shorter than an Earth year?

The answer is, you could observe the way the stars change around sunrise and sunset (or some other points in time fixed to the local sun, like solar midnight). The night sky will appear to rotate once over the course of a local sol

So what exactly is

[jimbobborg (128330)]

a super-earth? It is a bigger planet with Earth-like atmosphere, or it this just a bad translation?

Re:So what exactly is

[wile_e_wonka (934864)]

From TFA:

"With the advent of much more precise instruments such as the HARPS spectrograph on ESO's 3.6-m telescope at La Silla, we can now discover smaller planets, with masses between 2 and 10 times the Earth's mass," says Stéphane Udry, one of Mayor's colleagues. Such planets are called super-Earths, as they are more massive than the Earth but less massive than Uranus and Neptune (about 15 Earth masses).

Re:So what exactly is

[Vectronic (1221470)]

I think it just means its relatively solid, ie: non-gasious, plus they may deem it to be in the proper "zone" to become an earth-like planet (not too close, not too far)

Im not expert, but they (or at least one) may have an atmosphere of some sort, but I dont think anything that revolves around its sun that quickly, is likely to have "life", at least not intelligent life, they would have to be stupid yet productive, like insects...

Re:So what exactly is

[John Hasler (414242)]

> I think it just means its relatively solid, ie: non-gasious, plus they may deem it to be
> in the proper "zone" to become an earth-like planet (not too close, not too far)

With orbital periods of less than three weeks around a sun-like star they are going to be hotter than Mercury: far too hot for life.

Re:So what exactly is

[thegameiam (671961)]

It's a planet devoted to fighting crime, and supporting truth, justice, and the American way.

Such a downer...

[by Anonymous Coward]

Every time there's news of earth or super-earth sized planets, we always find that they're orbital period is like 5 days, which would mean the planet is completely scorched and incapable of supporting life or bearing liquid water. Such a downer....it doesn't matter what sized planet you have if its orbit places it so close to the star. Is this because the whole eclipse-detection method requires the planet to be close to its star so we can't actually detect planets further out from the star? I'm actually kind of tired hearing about "exciting" new of another planet being discover 5-30 million km from its star...that is not even close to being in the habitable zone people.

So...

[SirLurksAlot (1169039)]

What exactly makes these Earth-like? From the data it appears that their masses are several times greater than Earth and their orbital periods are much much shorter than Earth. Is it because the star they orbit is similar to Sol? Is there any indication of water or an atmosphere on any of them? Not that this isn't a cool find, but it seems that the use of the word "Earth" is just sensationalism. I would've been just as happy if they had simply said "three planets."

Re:So...

[oahazmatt (868057)]

Does it help to think of it as a project fork?

Re:

[SirLurksAlot (1169039)]

Ah, a software analogy, all is right with the world again!

Re:So...

[MozeeToby (1163751)]

The planets found are "earth-like" because they are believed to be rocky, terrestrial planets. Right now, we can only detect such small, lightweight planets when they are very, very close to their star.

The fact that we see so many of them gives some hope to the idea that there are many terrestrial planets out there and that some of them would be in the habitable zone. We can't yet see planets that might support life so right now we look for planets that share some characteristics with Earth, in this case size.

Re:

[DarthVain (724186)]

A more accurate description would be "Rocky and not a gas giant".

I think the point is that in the past we could only detect large gas giants, and now we can see smaller ones.

If I remember correctly the observed light from a star will wobble due to planets orbit around it. Larger the planet, bigger the wobble, and easier to see. Something like that anyway.

Oh and they don't actually see them, its is more like they make observations that they exist. They can do calculations to figure out density, but thats abo

Re:

[rcw-work (30090)]

This is simply anthropomorphism emerging yet again. Consider the term "extraterrestrial"; note the implication that an alien is based on terra (land.)

I believe it implies the alien is from somewhere other than terra (Earth).

DNA proven right once again!

[by Anonymous Coward]

> ... and is located 42 light-years away ...

So that was why the answer to the ultimate question was 42 - and the ultimate question itself must be something like "Are we alone in the universe, and if not, how many light-years away is the nearest other life?"

That close to a sun-like star...

[John Hasler (414242)]

---they can't be very Earth-like. "Super-Mercury" would be more like it.

42 light-years away?

[gmuslera (3436)]

Space race just found a new meaning for its life, its universe, and everything.

Nothing Earthlike about these planets

[icebike (68054)]

The planets, having 4.2, 6.7, and 9.4 times the mass of the Earth, orbit the star with periods of 4.3, 9.6, and 20.4 days, respectively.

Anything orbiting a star in 4.3 DAYS is extremely close to the star, and could not possibly anything more than a cinder, probably at near rock melting temperatures.

Mercury has an orbital period of 88 days for comparison.

Re:

[infernalC (51228)]

Clearly, these planets do not satisfy the Earth-like gravity requirement of a class M planet [wikipedia.org].

level of radiation

[tinkerton (199273)]

I haven't a clue about what level of radiation is still acceptable, except that I guess it's much higher than accepted.. Factors:

- Radiation can vary a lot along location, especially UV, and (primary)alpha and beta radiation is easily shielded. As for gamma, how much gamma radiation is there ten feet under water?

- Planets with tight orbits always have the same side to the sun due to tidal forces. This gives a wide range of temperature and radiation level to choose from.

- Radiation breaks down dna/rna and an

Can we ....

[PPH (736903)]

... swap Pluto for one?

42?

[sm62704 (957197)]

Has anybody seen Trillian?

Clearly these planets are only the tip of the iceberg."

Like tips of icebergs? Then they're NOT like earth but more like Neptune?? Wait didn't the summary say they were really really hot?

Huh?

Life Discovered!

[Doc Ruby (173196)]

"Tip of the iceberg"? We found icebergs on a trio of extraterrestrial Super-Earths? That means water! That means life! That means green super-women, out there for the asking, who haven't heard how weird it is to have a space nerd boyfriend!

Unusable as is...

[MiniMike (234881)]

but maybe when we get there we could turn them into 20.3 Earth-sized planets in a decent orbit. We could also take the extra 0.3 and make a moon for each planet, or maybe something fancy like a ring. Who knows, by the time we actually figure out how to get there, we might be able to do this too...

Sorry for not being funny, but

[drwho (4190)]

Sorry for not being funny, but I couldn't find an intelligent comment to attach this to, so it goes at at top level.

basically, my opinion is that it is within our reach to create a number of large telescopes that will exist roughly within the solar system, though possibly above and below the solar plane. These telescopes will be primarily automated, though a human team may need to be maintained ex-earth to do repairs and upgrades. All of these telescopes will be controlled by, and report to, all of the next generation super computers this race seems to be so good at creating (as opposed to high speed transportation systems). the ultimate goal is to be able to see the planets directly, and to observe and estimate the possibility for life as we know it (roughly). Where life does not exist, we seed it, though it may take generations to arrive, and thrive. This is our goal as a race, is to spread terran life as far as it can be spread. this is why the plants put up with us. It is our manifest destiny.

Re:Not good for much

[$RANDOMLUSER (804576)]

I think it's the "42 light-years away" that makes them less than useful.

Re:Please tell us more oh wise one

[dtolman (688781)]

Interesting science they are doing over there. So lacking any evidence that planets are ubiquitous, and even worse that true Earth-like planets exist in the first place even though they can't yet detect them, they are ready to say that they must exist because they have now found some "smaller" hunks of mass orbiting a star?

This is sheer idiocy. Astronomers are finding planets all over our immediate vicinity in space - how more ubiquitious can you get than the current rate of discovery? It seems any star with metallicity has a planet or planet system around it. As for the second part - the only limitation in finding Earth sized worlds is detector sensitivity. Seeing how they can find individual objects larger than Earth, and comet sized and smaller debris (in bulk), it seems pretty obvious they will find planets with masses the size of Earth, or smaller, as soon as we can get the sensitivity down to that point.

Re:

[dtolman (688781)]

Whose suprised? The first few planets last decade were suprises, because there was a real debate as to how rare planetary systems were. Now that we know they are common, its long expected that we will find Earth mass planets - the only question is when. The real suprises are coming when we look at overall systems (no one expected to find Jupiter+ massed planets in close orbits), or when we look at the atmospheres.

Depends on the radius of the planets

[JSBiff (87824)]

The actual force of gravity at the surface of a planet is not just a function of the mass of the planet. It is also a function of the radius of the planet. So, if a planet had more mass than earth, but also had a radius that was the right size, it could have the exact same surface gravity.

I believe the function is something like:

G * ( [M1 * M2] /R^2)

Where G is the universal constant of Gravity, M1 is the mass of a test object, M2 is the mass of the planet, and R^2 is the average radius of the planet, square

Correction

[JSBiff (87824)]

"Square-root of 2 times the mass of the earth" should read "Square-root of 2 times the radius of the earth".

Also, more generally, if the mass of a planet is X times the mass of the earth, then if the radius is also Sqrt of X times the radius of the earth, the Force of Gravity will be the same.