Recent studies of the triple star system closest to our solar system, Alpha Centauri, indicate that Centauri A hold slim chances of having formed super-Earth type worlds and only slightly better chances of Earth sized ones ( A Discouraging Look For Centauri A Planets ). But according to Paul Gilster, prospects of finding an Earth type world might be better if we took a closer look at the very closest star to us and the smallest stellar component of the Alpha Centauri System, the M-type red dwarf Proxima Centauri:
Today, M dwarf interest grows. There’s at least the chance of a workable ecosystem around such a star, assuming flare activity (common to these stars) might act more as an evolutionary stimulus than a deterrent to life. Moreover, the long lifetimes granted to M dwarfs mean that stable environments could exist for many billions — perhaps hundreds of billions — of years. This is why we’ve seen a recent florescence of M dwarf studies, with a keen interest in their astrobiological prospects, and why Proxima Centauri remains an interesting target. And although it hasn’t gotten the press of its larger siblings, Proxima has generated studies that are closing in on characterizing its system…
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We can already say this about Proxima planets: If they exist, they are no larger than 0.8 Jupiter masses in the range of orbital periods ranging from one to 600 days. That’s from radial velocity studies published in the late 1990s. This work is now complemented by seven years of high precision radial velocity data gathered with the UVES spectrograph at the European Southern Observatory. Michael Endl (McDonald Observatory) and Martin Kürster (Max-Planck-Institut für Astronomie) address the question of what kind of planets we can exclude from the habitable zone of Proxima Centauri based upon these data.
Proxima’s habitable zone, remember, is in close because this is a small star — the authors assume 0.12 solar masses, a reasonable estimate if on the high side, for reasons they explain in their paper. The habitable zone then becomes 0.022 to 0.054 AU, which corresponds to an orbital period ranging from 3.6 to 13.8 days. And the UVES data make it clear that no planet of Neptune mass or larger exists out to a distance of 1 AU.
For periods of less than 100 days, no super-Earths are detected larger than about 8.5 Earth masses. And for the actual habitable zone of Proxima Centauri we can rule out planets larger than 2-3 Earth masses in circular orbits. Needless to say, this doesn’t rule out planets of Earth mass or smaller in this zone.
Civilian mainstream science is getting better at detecting distant objects around other stars and it’s only a matter of time before an organization like an university or a non-profit discovers an Earth-type world for study.
Planetary Prospects Around Proxima
Update: Paul noted I was perhaps too extreme in my analysis of his post, so I made appropriate changes. In fact, he says prospects around Centauri B might be better than expected with improving search methods.
When Alpha Centauri is involved, no word is the last one! Corrections duly made Paul, thanks!
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The last time man set foot on the Moon was in 1972 when Eugene Andrew Cernan, last man on the Moon, boarded the Apollo 17 lunar module. That was 36 years ago and space flight has changed significantly since then, now NASA has more competition, as highlighted by Griffin during a visit to London:
“Certainly it is possible that if China wants to put people on the Moon, and if it wishes to do so before the United States, it certainly can. As a matter of technical capability, it absolutely can.” – Dr Michael Griffin
As to whether it actually matters whether China are the next to land on the Moon is open to interpretation. After all, the first nation to set foot on Earth’s natural satellite was the USA, so is a return trip a big psychological “victory” for China? “I’m not a psychologist, so I can’t say if it matters or not. That would just be an opinion and I don’t want to air an opinion in an area that I’m not qualified to discuss,” Griffin added.
This is more than a mea culpa, it’s a capitulation, as far as a credible civilian space program goes that is.
To me, this is proof that our military has already captured the high ground with advanced technology, why else would government mouth-piece Griffin show an obvious ‘could-give-a-shit’ attitude whether China gets to the Moon before Americans get ‘back’ there?
China Could Beat US in Moon Race
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Scientists at Brown University in Rhode Island used an instrument aboard a US spacecraft, the Mars Reconnaissance Orbiter, to hunt for traces of phyllosilicates, or clay-like minerals that preserve a record of water’s interaction with rocks.
They found phyllosilicates in thousands of places, in valleys, dunes and craters in the ancient southern highlands, pointing to an active role by water in Mars’s earliest geological era, the Noachian period, 4.6 to 3.8 billion years ago.
“These results point to a rich diversity of Noachian environments conducive to habitability,” the authors conclude.
An intriguing find was of deposits in the pointed peaks at the centre of craters. These peaks are generally taken to be underground material thrown up by an impacting asteroid or comet.
For water to be present in such peaks, it must have been present as much as five kilometres (three miles) below the planet’s surface, the paper suggests.
“Water must have been creating minerals at depth to get the signatures we see,” head researcher John Mustard, a professor of planetary geology, said in a press release.
I never seen the term “Noachian” applied to another planet other than Earth before.
Maybe Mars had a race of beings who fell from Grace like humans, only the opposite happened to them, instead of dying in a huge Flood, they died from a massive “dry-off”?
Aye, it’s a big Universe Mr. Scott!
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Dad, one slight tweak — I wouldn’t really say that prospects for both Centauri A and Centauri B are bleak (in terms of Earth-type planets), but rather that the prospects around Centauri A are now less positive because of the new paper we discussed on Centauri Dreams. Actually, B is quite a different story, and the authors of that paper are pointing out that their work covers only the highly specific configuration involved in Centauri A planets. We don’t have these methods applied to Centauri B yet (the smaller of the two binary stars), but everything else so far points to the real possibility of rocky worlds there.
Tweaks have been made Paul. 8)