Lots of Ink: A (rocky?) super-Earth just 22 light years away in habitable zone of red dwarf sun
This news broke Thursday afternoon and Friday. Ksjtracker skipped it yesterday as it was getting just a little stale. But new renditions of the news just keep popping up. The news is discovery, by a UC Santa Cruz and Carnegie Institution research team (plus co-authors all over), that a triple star system just 22 light years away has a so-called Super Earth planet with a mass estimated to be at least 4.5 times that of the real Earth. It orbits one of the triplet’s members, a red dwarf star, every 28 days (our days, natch) so it better be close to its bitty little sun to whip around that fast. The giveaway was a wobble in the star’s position, as measured by doppler shift. Red dwarfs, or M-stars, are pretty dim. Upshot: If it has a rocky surface and water, the radiation from the star ought to permit liquid water.
Another reason to post on this is because your tracker is ticked off. Some reports – including a television one I watched last night but now can’t find – say the world is at least 4.5 times bigger than Earth. “Bigger” is ambiguous – we talking radius, or volume? A big guy and a skinny guy may be equally tall. But the number is a mass ratio so no sense saying something like “bigger.” The TV show unambiguated the term exactly backwards: with a graphic showing Earth and, to scale, another planet 4.5 times as wide. It looked gigantic, far beyond super, around the size of Neptune. Gad. Such innumeracy is infuriating. Mass, as I am confident nearly every reader of this blog knows, is mostly a function of volume and of course density. Volume of a sphere goes up by the cube of radius. So if the mass is 4.5 times more, and assuming density is about the same, one takes the cube root of the mass ratio to get a diameter multiplier of 1.65. Bigger, but not monstrously. Sheesh.
Sample stories:
- Forbes – Alex Knapp: Astronomers Identify Another Possibly Habitable Planet ; Ah, droll sarcasm, as Knapp notes the star “has the very poetic name GJ 667C.”
- Christian Science Monitor – Pete Spotts: Planet found at perfect spot for life – in solar system with three suns;
- SF Chronicle – David Perlman: ‘Super-Earth’ planet spurs hope for billions more ;
- Time Magazine – Michael D. Lemonick: New Planet Found: Could a Super-Earth plus Triple Stars Equal Life? ; Interesting sidelight – astronomer Steve Vogt’s surmise that it’d take about 220 years to get a spacecraft there and radio back a closeup picture. One also has to add the time need to invent a space drive able to get the robot up to one tenth light speed on the way and then slow down enough to go into orbit (no sense going all that way just to whiz on through). I figure more like 500 years.
- Register – Richard Chirgwin: Jackpot; astronomers tag Goldilocks planet GJ 667C is practically a next-door neighbor ; No no, GJ 667C is the star (C for #3 in the three star system. The planet is GJ 667Cc, with the c for number three planet in the star’s family). This story is a Register science story standout, perhaps a new era? : no mention of boffins! Old guard Lewis Page and Lester Haines never missed a chance to anoint boffins.
- Space.com – Denise Chow: Newfound super-Earth might support life, scientists say ;
Why it is announced now is not obvious. It’s due out in Astrophysical Journal Letters. At the time of the release it was not even yet up on the arXiv astro-ph server (it is now, in grist below). While I’d not be surprised to see press officers have already begun timing publicity to arXiv postings, this is the first I have noticed.
Grist for the Mill: UCSC Press Release, Astro-ph Paper ; Carnegie Institution of Science Press Release ;
- Charlie Petit
February 7th, 2012 at 4:12 pm
Charlie, you’re dubious about going there? Remember, Vogt was talking about a space probe the size of a smartphone (in fact, he was talking about an actual smartphone), not some huge, unwieldy Voyager-type monster. Also, if it means doubling the length of the trip, I’d vote for whizzing on by and clicking the shutter very quickly.
But actually, I don’t think he was making a real proposal, just trying to dramatize how close the place is. Probably didn’t make that clear enough, though
February 7th, 2012 at 11:04 pm
What, is there something WRONG with droll sarcasm?
Also, no love for extrapolating that this is the home of the House of El? I’ll try harder next time.
February 8th, 2012 at 10:03 am
Michael, don’t get me wrong, I just figured that it’ll take a while to get anything, even a smart phone (I think Vogt proposed a droid, didn’t he?) and some kind of propulsion gear, up to one tenth the speed of light. That passage was fine, and distinctive, and witty of hm to say it and you to report it. Actually, for less money and faster payoff, we might get a decent picture from here with a whopping long-baseline and whoppingly costly interferometer in space and see continents, glints of oceans, do atmospheric spectroscopy, etc. That’d take awhile and a budget nobody is going to approve any time soon. THEN if we spot a really earthlike world, somebody can put a teeny camera on a gossamer space kite and keep a monstro laser aimed at it till its going screaming fast and we’re off. Navigation might be tough.
February 8th, 2012 at 10:04 am
Alex – Droll good. Sarcasm good. Both: even better.
February 8th, 2012 at 3:27 pm
I do see your point about “mass” vs. “size. But apart from that, there’s also an elephant in the room. It’s this E-print here by Bonfils et al.: http://arxiv.org/abs/1111.5019v2 – published on astro-ph in November 2011.
It’s based on the HARPS data also mostly used by the UCSC/Carnegie group who are now reported in the popular press as the discoverers GJ 667Cc (in fact, the article is by the people who built HARPS and actually took the data). The preprint identifies GJ 667Cc, gives its orbital period, gives a mass estimate not dissimilar to the one by Anglada-Escudé et al., and hypothesizes that it could be a habitable planet, since it gets about 90% the amount of radiation the Earth gets from the Sun.
So who’s the discoverer of the new planet? The preprint by Bonfils et al. was out in electronic form earlier, but the article is not accepted in any journal. It also references, for GJ 667Cc, an article that is still “in preparation”. On the other hand, it does give the basic parameters, and shows that Bonfils et al. evidently found GJ 667Cc in their HARP data. Anglada-Escudé et al. cite this preprint, although if you only browse their article cursorily, you might miss the fact that “similar to one of the candidates reported here” refers to GJ 667Cc that everyone is now making such a fuss about.
There are some subtleties here involving priority in the age of electronic publishing; the way the story is now widely reported seems blatantly unfair, though. And so far, I haven’t come across anyone reporting this.