Planet around Proxima centauri

lunatio_gordin · Jun 24, 2005

I seem to recall having read somewhere that there was a gas giant planet detected around Proxima. Now, i can't find this information. after a few internet searches, i've only found one inconclusive study that said there could be a 0.8 jupiter mass planet, dated from 1994. can anyone help me out with this?

vogon13 · Jun 25, 2005

IIRC, Hubble image was believed to show possible object near Proxima, but, I think it turned out to be a background star. Sorry my recollection of this isn't very clear. Initial report got some media play, retraction languished below the tide listings in the paper. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

lunatio_gordin · Jun 25, 2005

i read this in 2003, maybe. I'm pretty sure it wasn't that report, though. would it be reasonable, for science fiction purposes, for me to "Create" a gas giant meeting those specs there?

vogon13 · Jun 25, 2005

Gas giants turning up around many stars, seems quite possible Proxima could have one too. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

lunatio_gordin · Jun 25, 2005

Hmm. so, with my planet, could the electromagnetic field be strong enough to protect a moon from solar flares common among M class dwarf stars, but still not be destructive to life on said moon? and, if the moon were, say, tidally locked around this planet, could that also help to prevent it from being fired by the flare?

formulaterp · Jun 25, 2005

Here is a list of all extrasolar planets found to date: http://planetquest1.jpl.nasa.gov/atlas/atlas_search.cfm Nothing for Proxima Centauri, looks like the closest is Epsilon Eridani at 10 lightyears. Regarding your hypothetical planet/moon. Hey it's Sci-Fi, you can do what you want. If your planet has extensive radiation belts, and the planet's magnetic poles are just right, your moon's close orbit may keep it protected to some extent. I'm not sure how tidally locking your moon would be of any benefit, though. Keep in mind that Earth's primary line of defense against solar flares, cosmic rays or CME's is not the radiation belt, but rather the atmosphere.

serak_the_preparer · Jun 25, 2005

. . . would it be reasonable, for science fiction purposes...? It was once considered impossible for red dwarf stars to support life-bearing planets. But, more recently, closer looks at the idea have prompted some reconsideration. The best information available on the Web about the Alpha Centauri system may be here: Alpha Centauri 3 The following is drawn from the site: Like many red dwarfs, Proxima is a "Flare Star" that can brighten suddenly to many times its normal luminosity. Its flares can roughly double the star's brightness and occur sporadically from hour to hour. Moreover, more than one flare may be emitting at a time. From May to August 1995, several flares were observed with changes within a time-scale of weeks, and archival data suggests that the star may have a long-term activity cycle (Guinan and Morgan, 1996).... And: Using data collected up to early 1994, astronomers using the Hubble Space Telescope discerned a 77-day variation in the proper motion of Proxima (Benedict et al, 1994). The astrometric perturbations found could be due to the gravitational pull of a large planet with about 80 percent of Jupiter's mass at a 1994 separation from Proxima of about 0.17 AUs -- 17 percent of Earth's orbital distance in the Solar System from the distance, or less than half Mercury's orbital distance. The Hubble astrometry team calculated that the chance of a false positive reading from their data -- same perturbations without a planet -- to be around 25 percent.... So Proxima's flares do pose the greatest c

spacefire · Jun 25, 2005

let's go there and see. it's fairly close. <div class="Discussion_UserSignature"> http://asteroid-invasion.blogspot.comhttp://www.solvengineer.com/asteroid-invasion.html </div>

serak_the_preparer · Jun 25, 2005

Or at least devote some quality observing time to it on our best instruments now and in the future. Our closest neighbor - which includes a twin of our Sol - and yet we don't really know that much about it. Not sure why Alpha Cen has received so little attention, though it may have something to do with its location in the southern hemisphere.

severian · Jun 25, 2005

Wel, for Sci-Fi purposes, you could probably get away with more or less anything. There is no scientific reason why you couldn't find a gas giant around Proxima Centuari, although due to the flares it would probably not be as close to the star as many of the other gas gaints we have found so far. Sadly the Alpha Centuari stars (all three of them) are not very good candidates for earth-like planets, proxima being too small, and the other two being a binary star (which would mean that any stable orbital distances would be too far away).

serak_the_preparer · Jun 25, 2005

Severian, Don't give up hope just yet. If you check out the link given in my earlier post - Alpha Centauri 3 - you'll see there's room for some optimism: In a binary system, a planet must not be located too far away from its "home" star or its orbit will be unstable. If that distance exceeds about one fifth of the closest approach of the other star, then the gravitational pull of that second star can disrupt the orbit of the planet. Recent numerical integrations, however, suggest that stable planetary orbits exist: within three AUs (four AUs for retrograde orbits) of either Alpha Centauri A or B in the plane of the binary's orbit; only as far as 0.23 AU for 90-degree inclined orbits; and beyond 70 AUs for planets circling both stars (Weigert and Holman, 1997). Hence, under optimal conditions, either Alpha Centauri A and B could hold four inner rocky planets like the Solar System: Mercury (0.4 AU), Venus (0.7 AU), Earth (1 AU) and Mars (1.5 AUs).... Viewed from a planet at Earth's orbital distance around Alpha Centauri A, this companion B star would provide more light than the full Moon does on Earth as its brightest night sky object, but the additional light at a distance greater than Saturn's orbital distance in the Solar System would not be significant for the growth of Earth-type life. According to Weigert and Holman (1997), the distance from the star where an Earth-type planet would be comfortable with liquid water is centered around 0.73 to 0.74 AU -- somewhat beyond the orbital distance of Venus in the Solar System -- with an orbital period under an Earth year using calculations based on Hart (1979), but more recent calculations based on http://adsabs.harvard.edu/cgi-bin/n...993Icar..101..108K&db_key=AST</safety_wrapper

lunatio_gordin · Jun 25, 2005

is 0.17 AU close enough for liquid water to exist? for my purposes, i was trying to use real scientific data to construct the story. now, i have a different question: Is an AU the distance from the center of the Earth to the center of the sun, or from the surface of the Earth to the surface of the Sun?

odysseus145 · Jun 25, 2005

This is what Celestia says it would look like from .17 AU. It doesn't give a temperature, but it doesn't look like it would be very warm at all. <div class="Discussion_UserSignature"> </div>

robnissen · Jun 25, 2005

"Any statements that spectroscopic findings from other planets found around other stars have confirming characteirstics of life, as this article specifically states, are terribly premature & very likely wrong." JEEZ. The article you are whining about is SCIENCE FICTION. The fact that it has a date of 2015 MIGHT HAVE GIVEN YOU A CLUE!!!

serak_the_preparer · Jun 26, 2005

"Any statements that spectroscopic findings from other planets found around other stars have confirming characteirstics of life, as this article specifically states, are terribly premature & very likely wrong." JEEZ. The article you are whining about is SCIENCE FICTION. Rob, Thanks! I thought my introduction to the excerpt - 'This amusing take on the discovery of a civilization in the Alpha Centauri system, by the way, is taken from Dreaming of a Discordian Sky, a fun future history' - also offered a few clues. Oh, well. If Orson Welles' 'War of the Worlds' broadcast back on Oct. 30, 1938, could panic thousands, why shouldn't Robert Anton Williams' and Robert Shea's trilogy (or its derivatives) produce a similar effect? <img src="/images/icons/wink.gif" /> As for the statement giving out that the Alpha Centauri system is trinary, the jury is still out on that point. Astronomers remain unsure whether Proxima is merely temporarily associated with Alpha Centauri A and B or whether it is actually attached to the system via a very long orbit. The more relevant binary heart of the system, A and B, however easily allows for stable orbits in the respective habitable zones of both stars. Though, for all we know, there may not be a single planet in any of those orbits, then again there just may be one, or even more than one. Here's hoping!

lunatio_gordin · Jun 26, 2005

Proxima is a lightyear away from the other two. I think it wouldn't be that bad of interference. How high would the moon's orbit need to be? would a 36 earth-day orbit be enough?

serak_the_preparer · Jun 26, 2005

Lunatio, we used to have a resident astronomer on these boards at the 'Ask the Astronomer' forum. A great guy, very fair, and excellent at finding the answers. He was - and doubtless still is - greatly missed after he moved on to other pastures. It would be fantastic if Space.com would appoint a successor to that post. Unfortunately, I don't have the answer to your question handy. Perhaps some digging on the Web could turn something up which you could use. The Alpha Centauri site I included in earlier posts to this thread remains one of the best sources I've come across - also, it was designed for writers such as yourself to use. Still, some digging I did a few months ago may help: Realism of Red Dwarf Earths?

lunatio_gordin · Jun 26, 2005

I'm surprised at how hard it is to find info on Proxima and Alpha centauri. I'd have imagined they would be the stars with the most known about this. i guess most sci fi writers get off making stuff up.

vogon13 · Jun 26, 2005

Data for most known (individual) stars is quite similar. Mass, color, location in space, etc. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

lunatio_gordin · Jun 26, 2005

i lso keep stumbling by only finding their location in the sky, not in space. Sure, Ups And is 44 lightyears away from here, but in what direction? is it 40 or 48 from Proxima? this is more exemplary of my problem. Since my characters travel from star to star, i need to know how far from that star the next one is. The best thing i've found was the star chart of places within ten ligtyears of Proxima.

vogon13 · Jun 26, 2005

It's when something unusual (or unique) is discovered about a specific star that it becomes 'famous'. Barnard's Star - large proper motion That weird star in LMC that Ian Shelton discovered in 1987 Father Guido Sarducci's 'coming and going' star S. Doradus etc. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

vogon13 · Jun 26, 2005

Software to generate star to star distances probably not all that complex to figure out. If angle between Proxima and Ups and in our sky is 90 degrees (I picked an easy angle to do in my head, of course) then distance is roughly 46 ly. IIRC, most of these distances aren't known that accurately anyhow. Over 50 ly out to whatever, errors get very large. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

serak_the_preparer · Jun 26, 2005

I'm surprised at how hard it is to find info on Proxima and Alpha centauri... You and me both. Though I'm sure there must be one, I've never really heard a good and convincing argument explaining why so little attention has been paid to our nearest neighbor. Did you check out the Alpha Centauri 3 site, by the way? Just now I took a look and found: 'Accounting for infrared radiation, the distance from Proxima where an Earth-type planet would be "comfortable" with liquid water is around 0.02 to 0.06 AU (Endl et al, 2003, in pdf) -- much closer than Mercury's orbital distance of about 0.4 AU from Sol -- with an orbital period of two to 16 days.' But, since much of this is speculation - or science fiction - then, just as Severian suggests, there's plenty of wiggle room. For instance, why can't a mild greenhouse effect be in play? Your atmosphered moon could have a thick atmosphere. Also, your moon is clearly planet-sized, a situation along the lines of Niven's Jinx. The world with the biosphere could be more massive than Earth. The entire Proxima I (or II?) system masses around 254 times the mass of Earth. The life-bearing world - planet, moon, call it what you will - masses at around 1.3 or so what Earth does, but is only a little bigger. Make it a little more dense than Earth to give it a higher gravity, that thick atmosphere, and plenty of metals. A planet similar to Jupiter may command an impressive magnetic field. Jupiter's reaches 2 or 3 million miles toward our sun, easily big enough to encompass its moons. So why not a 36-day orbit? That's basically a little more than double Titan's 16-day orbit about Saturn (placing it somewhere between Hyperion and Iapetus, if your world were part of Saturn's system - somewhere out between Callisto

lunatio_gordin · Jun 26, 2005

my questions are pertaining to scifi. We're speaking entirely hypothetically here. Yes, i've spent a great deal of time looking at that website. If i understand you right, i need to make my planet more massive, correct? right now, i had it rather small, slightly larger than Mars. If i have our .8 jupiter mass planet, Atlas, could it hold a world 1.3 times the mass of Earth? and could this earth-moon have another moon approximateyl the size of say, our moon, or pluto?

serak_the_preparer · Jun 27, 2005

Then if it's sci fi it doesn't belong in this topic. As Lunatio has already pointed out, the topic is hypothetical and speculative; i.e., it pertains to science fiction. The discussion here is focused on a world invented for science fiction purposes. and it needs to be VERY clearly ID'd as such. It was. I introduced the material as 'a fun future history.' The date 2015 was bolded. That the excerpt a) describes 'half the radio transmitters on Earth' abruptly turning their attention to Alpha Centauri to broadcast messages of greeting, b) states that '[a]lien mania dominates the news for a month or two,' and - most of all - c) proclaims the successful detection of an extraterrestrial civilization are all enormous clues. There is also the Terrestrial Planet Finder. It's mentioned in the first line of the piece, and the glowing green link set off from all the other quoted text - The TPF Image of Alpha Centauri A II [Osiris] - refers directly to the TPF project. Which is due to launch in 2014. I also provided the link Dreaming of a Discordian Sky, which, if used, leads directly to the science fiction site. The fact that you wrote, 'the source is tainted by not knowing the difference between speculation and fact and is making false statements,' suggests to me that you never actually investigated the source. Though you went on to write, 'these kangaroo like leaps of conclusions are entirely too common around here,' you made such a leap yourself. Mark it more clearly, as many people have been MISLED by your posting of it. No other posts to this thread give evidence of others having mistaken the science fiction piece as a factual account. & if it's SCI FI, then post it there, n

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