HARPS Discovers 32 New Exoplanets
Written by Nancy Atkinson
A planet 6 times the mass of Earth orbits around the star Gliese 667 C, which belongs to a triple system. Credit: ESO
Astronomers have found 32 new planets outside our solar system with the High Accuracy Radial Velocity Planet Searcher, better known as HARPS, the spectrograph for the European Southern Observatory's (ESO) 3.6-metre telescope. The number of known exoplanets is now at 406, and HARPS itself has discovered more than 75 exoplanets in 30 different planetary systems. Included in this most recent batch are several low-mass planets – so-called "Super Earths" about the size of Neptune. The image above is an artist's impression of a planet discovered that is 6 times the mass of Earth, which circles the low-mass host star, Gliese 667 C, at a distance equal to only 1/20th of the Earth-Sun distance. Two other planets were discovered previously around this star.
"HARPS is a unique, extremely high precision instrument that is ideal for discovering alien worlds," said ESO astronomer Stéphane Udry. “We have now completed our initial five-year program, which has succeeded well beyond our expectations.”
No Earth-like planets were discovered in this group that was announced today at an exoplanet conference in Portugal.
HARPS has facilitated the discovery of 24 of the 28 planets known with masses below 21 Earth masses. As with the previously detected super-Earths, most of the new low-mass candidates reside in multi-planet systems, with up to five planets per system. This new group includes a total of 11 planets with masses between 5 and 21 times that of Earth – and 9 in multi-planet systems — and increases the number of known low-mass planets by 30%.
HARPS uses the radial velocity technique which measures the back-and-forward motions of stars by detecting small changes in a star’s radial velocity as it wobbles slightly from a gentle gravitational pull from an otherwise unseen planet. HARPS can detect changes in velocity as small as 3.5 km/hour, a steady walking pace.
Notable discoveries by HARPS during the past five years include the first super-Earth in 2004 (around µ Ara; ESO 22/04); in 2006, the trio of Neptunes around HD 69830 (ESO 18/06); in 2007, Gliese 581d, the first super Earth in the habitable zone of a small star (ESO 22/07); and in 2009, the lightest exoplanet so far detected around a normal star, Gliese 581e (ESO 15/09). More recently, they found a potentially lava-covered world, with density similar to that of the Earth’s (ESO 33/09).
“These observations have given astronomers a great insight into the diversity of planetary systems and help us understand how they can form,” says team member Nuno Santos.
Source: ESO
Filed under: Extrasolar Planets
Tags: Extrasolar Planets, HARPSRelated stories on Universe Today
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October 19th, 2009 at 8:45 am
Wow! And it's confirming the low mass trend, AFAIU.
October 19th, 2009 at 11:49 am
Time to start commoditizing planets…
October 19th, 2009 at 2:32 pm
How can we detect what atmospheres they have?
October 19th, 2009 at 4:43 pm
Exciting news! I always loook forward to articles about exoplanet discovery. It should only be a matter of time before we discover an Earth-sized planet in the habitable zone. As far as determining atmospheres, I believe we'd need to send a probe, ie Cassini, but I may be wrong. Anyone?
October 19th, 2009 at 4:57 pm
I wrote a book on the physics involved with sending probles to other stars. it is not easy to do. Probably the best approaches are to either put large solar columating Fresnel lenses in space to propel a sailcraft, or to send nano-tech devices by electromagnetic means.
These planets are not likely to be very habitable. They are large and likely tidal locked with their star, just as the moon shows one face towards the Earth. Yet the discovery of these planets does inidcate a progress towards finding smaller more habitable ones.
LC
October 19th, 2009 at 5:17 pm
@William928
If the planet passes in front of its star it is possible to get some indications of its atmosphere from here on Earth. We can learn about the chemical composition of a star by taking its spectrum and carefully studying it. When the planet moves in front of the star the star's spectrum will change a tiny bit because some of the light from the star passes through the planet's atmosphere, and we can learn something about the composition of the atmosphere. The trouble is that only very few planets orbit in such a way that they pass directly between us and the star.
If it was possible to resolve the planet (that is, see it as a distinct point of light next to its star), we could do spectroscopy on it directly. But extrasolar planets are so far away and so faint compared to their star that they are lost completely in the glare. We need much more powerful and precise telescopes than we currently have.
Sending a probe would get the job done, assuming it survived the trip through interstellar space, but in the thousands and thousands of years it would take to get there we would have developed the cool telescopes we need to study extrasolar planets from here.
October 19th, 2009 at 5:21 pm
Sooo… they do that right here in the old country, and I don't even receive an invitation, huh?
Preposterous!
October 19th, 2009 at 6:34 pm
@Nexus
Thank you for the information. I realize that with our current technology, it would take a very long time to send a probe to any of these exoplanets. It seems that more powerful and precise telescopes will have to be the ticket, as you describe the inherent difficulty in conducting direct spectroscopy. At least we're continually discovering more exoplanets. This is one of my favorite aspects of astronomy.
@LC
I've reviewed some to the pages of your book, it looks interesting, I may have to pick up a copy, but $45? Maybe it would be possible to find a used copy to save a few dollars in these challenging economic times? In any event, thank you for offering your insight.
October 19th, 2009 at 6:35 pm
errr…. some of the pages….sheesh, too much typing today.
October 19th, 2009 at 6:58 pm
Apologies if I missed this, where are these planets located?
Also, there has been talk about someday traveling to these planets if there were life found. I don't see that happening if anyone in charge at that time has common sense. If one microbe from our planet were to survive that trip, it could be a death sentence for everything on their planet.
October 19th, 2009 at 7:48 pm
uncledan Says:
October 19th, 2009 at 6:58 pm
"If one microbe from our planet were to survive that trip, it could be a death sentence for everything on their planet."
Possibly, although I think that there is a bit of a misconception surrounding this issue. I presume you refer to the fact that lifeforms there would have very little immunity against our diseases. True, but don't forget that diseases that affect organisms on our planet are also highly adapted to do what they do – they affect other organisms in precise ways and require specific conditions to flourish. It is no stretch to say that the organisms of our planet and the other organisms that infect them co-evolved, and so any microbes from our planet would be likely to find that hosts on other planets are a terribly hostile environment for them to grow in, as opposed to our microbes decimating the local populations through lack of immunity…
October 20th, 2009 at 12:12 am
Nexus:
More likely that we would have developed warp-drive and got a manned mission there before the bloody probe arrived.
October 20th, 2009 at 12:49 am
Perhaps. I'm hopeful that warp technology is achievable, but I have serious doubts. But that's a discussion for a different topic.
October 20th, 2009 at 1:08 am
"Oh my God—it's full of planets!"
@ William928:
Here is a recent paper from Astrobiology on "The far future of exoplanet direct characterization" by Schneider et al. After walking through a series of possible generations of studies by diverse telescopic techniques, they take a perhaps less serious outlook on the very far future:
"If we suppose that around 2020-2030 one has found a promising biomarker candidate on a nearby planet (like for instance around alpha Cen (Guedes et al. 2008). Such a discovery would trigger two kinds of projects:
> Direct visualization of living organisms. Suppose that one wants to detect directly the shape of an organism having a size of 10 meter. A spatial resolution of 1 meter would be required. [...] In addition, it this organism is moving with a speed of 1 cm s^-1 it must be detected in less than 1000 sec. To get a detection in 20 minutes with a SNR of 5, the collecting area must then correspond to an aperture B = 3 million km. All these numbers are unrealistic, unless laser trapped mirrors proposed by Labeyrie et al (2009) finally succeed (in their present conception there are fragilized by the solar wind).
> Exploring nearby stars. The possibility to explore in situ nearby stars at a speed of 0.3 c is often invoked (see for instance Bjoerk 2008). [...] No presently available technology can protect against such a threat without a spacecraft having itself a mass of hundreds of tons, in turn extremely difficult to accelerate up to 0.3 c. A way around is to have a travel velocity of only a few hundred km/sec like for the “The Project” project (Kilston 1999). But then the journey will take 10,000 years to go to alpha Cen.
Whatever the approach, it seems impossible to have a direct visual contact with living organisms on the nearest exoplanet before many centuries, at least in the framework of foreseeable physical and technological concepts, and what physics will be in 1,000 years is not reasonable to anticipate. We are thus limited by a kind of conceptual or knowledge horizon."
@ uncledan:
I'm with Astrofiend in this, it is a misconception to forget adaptation and coevolution when discussing this. Astrobiology isn't as situated in basic evolution of biology as the name implies.
Other misconceptions that bear on this issue is the feasability of extremophiles (that thrives in extreme environments) and methanogens (that thrive on simple carbon sources). Both of them are late in the fossil record, and if you believe the neomura theory of Cavalier-Smith they are the twins of also late eukaryotes that genome sequencing and structural phylogeny hints at.
This seems natural, as early organisms are unlikely to be sturdy and also unlikely to utilize oxygen as needed in aerobic methylothrophy/methanotrophy and the related methanogen metabolism as oxygen atmospheres are products of biospheres. Aerobic methanotrophy is claimed to be needed for direct scavenging of methane from an atmosphere. [An interesting exception of alternative oxygen source, albeit again with a long delay before availability, is the one recently suggested for Europa by photo production and ice convection.]
In the neomura theory it was very unlikely that earlier organisms, bacteria, trapped in their non-extremophile yet sturdy protein exoskeleton cell wall, would be able to loose it to develop a new extremophile one (archaebacteria) respectively develop an endoskeleton flexible cell (eukaryotes). It only happened once, and relatively late in Earth history.
It is also unlikely that exoplanetary bacteria analogs would be able to hit on extremophile proteins for cells walls from the start. There is AFAIU a specific membrane transport system that needs to be developed, and so on and so forth.
This adds up to that exoplanetary biospheres must start out relatively benign even if they later turn harsh. (So, say, Mars is today a possible habitat for extremophile analogs but only if it was as much more habitable at the outset as believed.) And that simply production of, or access to, simple hydrocarbons isn't a good marker for biospheres, or at least young and/or simple ones.
October 20th, 2009 at 1:43 am
"twins" – sisters, in biological parlance.
October 20th, 2009 at 3:25 am
On this subject, anyone have any news of how the Kepler mission is going?
October 20th, 2009 at 5:28 am
@ Nexus:
It might be possible to detect atmospheric chemistry by looking at the starlight through the gasses. However, it has been said that finding a planet around another star is like detecting a moth around a searchlight from 100 km away. Detecting atmospheric chemistry would then be like trying to detect the size of the moth's wings.
Sending a low gamma spacecraft to another star is possible in the not too distant future. A large Fresnel lens that concentrates solar light on an ultrathin sail craft could accelerate it up to gamma = 1.2. Gamma is the Lorentz factor in special relativity
gamma = 1/sqrt{1 – (v/c)^2}.
which is also a measure of the amount of energy one can impart to a craft. Gamma = 1.2 is v = .55c. This means you could get probes to stars within 10 light years out in about 25 years and it would of course take another 10 years to get information back. That might sound like a long time, but the Voyager crafts took 10 years to complete their interplanetary missions and are still giving data on the heliopause.
Torbjorn Larsson is right that these types of missions are possible most likely at least 50 years or more from now. I have done some calculations on the prospect of using VASiMR propulsion to explore the Kuiper belt region and beyond within < .1 light years. It would be interesting if a black hole (a rougue black hole) were detected perturbing bodies in the Kuiper belt or the Zodiacal region of dust. We might do some direct exploration. Though I admit the chances of this are remote.
Yet we are not really going to understand the environments of extrasolar planets without putting a probe directly in these stellar systems. In particular, it will require a probe on the surface of a planet to study the extraterrestrial biology of such a planet.
LC
October 20th, 2009 at 12:43 pm
@ Ivan3man
Yeah, but then we could watch the arrival of the probe and see if it's still working.
The problem I have with a probe sent to exo-planets is that it does not only take a hugh amount of time to get there, but also to receive the data. Two annoying things.
October 20th, 2009 at 2:55 pm
If you send people to other stars you have the same problem. Back on Earth you have a long wait before getting any information. Also the costs would be enormous.
A comparatively modest interstellar probe could be lofted in the not too distant future. A very thin 10 km radius solar sailcraft with a mass of 10^5 kg. could accelerate at a ~ .1m/s^2 from solar light directed from a 10km radius Fresnel lens. This could reach a gamma = 1.2, or about .5c. The sail craft would separate and reflected radiation off the larger annulus would then brake the smaller sail disk. Of course this would not come cheap, but it is not out of bounds. The payload could be a 25 ton craft which uses the remainng sail to navigate around the stellar system. Possibly small landing probes could be dropped on planets.
A piloted stellar craft would be many orders of magnitude larger and massive. It would offer no advantage for scientists on Earth, for they would still have to wait for the data to return.
LC