Earth's 'bigger cousin' detected

[Math Is Hard]

SPACE.com -- Astronomers announced Monday the discovery of the smallest planet so far found outside of our solar system.

About seven-and-a-half times as massive as Earth, and about twice as wide, this new extrasolar planet may be the first rocky world ever found orbiting a star similar to our own.

"This is the smallest extrasolar planet yet detected and the first of a new class of rocky terrestrial planets," said team member Paul Butler of the Carnegie Institution of Washington. "It's like Earth's bigger cousin."

http://www.cnn.com/2005/TECH/space/06/13/extrasolar.planet/index.html

 

[Adrian Baker]

Wow - interesting stuff. Doesn't sound too hospitable though!

 

[tony873004]

1.9 g surface gravity. It would be interesting how that would affect the development of life.

 

[Math Is Hard]

We're starting to get really good at this extra-solar planet detection stuff!
I am amazed at how much scientists can figure out from a little wobble.

 

[DaveC426913]

A rocky planet, with 2G gravity, 15 light years away...

That's WAY cool!

 

[marcus]

smallest exoplanet around a main sequence star

http://www.spaceref.com/news/viewnews.html?id=1031

minimum mass 6 x earth.
primary =Gliese 876
red dwarf star about 1/3 mass of sun
period of about 2 days (1.9 days)
guessed to be rocky, but may have some atmosphere
estim. temp. 400-700 fahrenheit

http://www.universetoday.com/am/publish/large_rocky_planet.html?1362005

http://skyandtelescope.com/news/article_1530_1.asp

Here too is a BBC article
http://news.bbc.co.uk/1/hi/sci/tech/4089534.stm

too hot to live on, but hey, it is only 15 lightyears away!

 

[ohwilleke]

Already covered in the Earth's bigger cousin thread. Ideally, the two should probably be merged.

 

[marcus]

I found some more links about this exoplanet find.
Here are some graphics
http://exoplanets.org/gl876_web/gl876_graphics.html

this includes a plot of data

and two videos----a computer simulation of a flyby of the system and an overview of the system showing orbits of its three planets.

and also it has some "artist conception" graphics of the system


Here is a central website
http://exoplanets.org/
this site currently features links about Gliese 876

NSF announcement
http://nsf.gov/news/newsmedia/planetdiscovery.jsp
NSF press release
http://exoplanets.org/gl876_web/press_release_NSF.htm
Technical data from the report submitted for publication
http://exoplanets.org/gl876_web/gl876_tech.html

...the two should probably be merged.

Either way fine with me. I didnt see the other thread. basically I just want to put the links up in case a phrase like "lowest mass exoplanet" rings a bell for anyone and they should have some links to follow to find out more

Whoah! here is a manuscript of the draft technical article they have submitted to Astrophysical Journal!
the link is down at the bottom of the page here
http://nsf.gov/news/newsmedia/planetdiscovery.jsp
it says
"Draft of the paper, A ~7.5 Earth-Mass Planet Orbiting the Nearby Star, GJ 876"

I tried downloading. So we can get the journal article itself, the day after it gets to popular media.

this Gliese 876 system is interesting. It is real close to us: 15 lightyears. and also it is the lowest mass star known to harbor planets. It could be the destination of a probe some day. Like, not to this hot rock but to the two jupiters farther out.

 

[marcus]

Wow! at least one of the other two planets might be a reasonable temperature!

they would be "jupiters" (gas giants) but they could have moons like Jupiter has moons

the interesting thing is the wattage per square meter

the luminosity of the star, Gliese 876, is 0.0124 of the Sun
so about one percent of sun

however the nearer of the two giants is at 0.10 AU
so the "solar constant" there would be about 1.24 times earth
which means the equilibrium temperature would be nearly the same as here at earth.

the Harvard catalog is a good source of information, see
http://cfa-www.harvard.edu/~planets/Gl876.html

 

[marcus]

in another thread someone was talking about nearby habitable exoplanets

and I think Gliese is interesting in that context because it has 3 planets, inner one too hot, outer one too cold but the middle planet
has a "solar constant" (incoming radiant energy per unit time per unit area) about the same as the earth's

I should say Gliese 876, not just Gliese

anyway the middle planet (that is roughly the right temp) is a giant like Jupiter which is a bit daunting, but it could have satellites like the jovian satellites (except they would have dried out because so much warmer, probably)

it is only 15 lightyear off, so I'd say check it out. at one percent c it would only take 1500 years to get there---well? any thoughts?

 

[Nereid]

Already covered in the Earth's bigger cousin thread. Ideally, the two should probably be merged.

Merged; thanks for the suggestion ohwilleke.

 

[Dr.Brain]

it is only 15 lightyear off, so I'd say check it out. at one percent c it would only take 1500 years to get there---well? any thoughts?

Maybe you can sit in a spaceship which can make fuel out of dark-matter and take a girl with yourself ( no harm intended if you are married ),20 generations later , you are there , wow!

 

[cDimino]

Why is 700 degrees f too hot? Can no life survive those temperatures, even alien life? Is there anything on Earth known to live through such heat?

 

[marcus]

Maybe you can sit in a spaceship which can make fuel out of dark-matter and take a girl with yourself ( no harm intended if you are married ),20 generations later , you are there , wow!

you are jumping ahead Dr. Brain.

for starters people are going to study the Gliese 876 system intensively using telescopes groundbase and in orbit----it is a really interesting system with its 3 planets

(I think the two jupitersize ones are in 2:1 resonance with period 30 days and 60 days)

then quite possibly after a long time has passed and a lot has been learned about the system, people will want to send an unmanned probe.

the main target of interest for the probe could be something in the system we do not know about yet, but it could also (I speculate) be the jupitersize planet with 30 day orbit that can be expected to be roughly
SAME TEMPERATURE AS EARTH and which may have satellites

even discounting the possibility that it has evolved life or even could support earthkind of life----even completely setting aside the life issue---this is one extremely interesting system. imagine a planet like Jupiter but at about the same distance from the sun as Earth is so that it is roughly Earth temperature.

actually a bit colder. the middle planet at Gliese 876 gets about 124/169 of the sunlight wattage per unit area that the Earth does (according to harvard catalog numbers) and equilibrium temp would be about 92 percent of what it is at Earth distance from sun-----so average temp could be below the H2O freezing point although midday temp could be melting. the harvard catalog data isn't really accurate enough to suppose much

anyway this is a premier target for bigtime study, probably will be for centuries

so let's figure out where it is in the sky!

the magazine Sky and Telescope says this:

The star itself is in easy reach of amateur telescopes. Using a detailed, large-scale star atlas, you can find it glowing orange at right ascension 22h 53m 13s, declination –14° 15' 13" (2000.0 coordinates). It's in the bottom of Aquarius's water bucket, as Sky & Telescope draws the constellation, ...

 

[Dr.Brain]

I was talking about what we should do if we had to plan a manned flight to one of those planets.

BJ

 

[marcus]

I was talking about what we should do if we had to plan a manned flight to one of those planets.

BJ

I've been thinking about that, what you suggested. here is a webpage about the habitable-zone planet in that system

the planet is called Gliese 876 C

(I guess the primary is A and the planets are called B, C, and D
B is too cold and D is too hot but C is about same temp as Earth or a bit colder sometimes)

http://www.extrasolar.net/planettour.asp?StarCatId=&PlanetId=156

 

[marcus]

BTW here is a link to some information about another interesting system
HD28185

http://www.extrasolar.net/
I can't get a direct link. only way I can see is to scroll down
to where it says HD28185
Oh wait, maybe this is a direct link
http://www.extrasolar.net/startour.asp?StarCatID=normal&StarID=130
http://www.extrasolar.net/planettour.asp?StarCatId=normal&PlanetId=158

another interesting one might be HD108874
http://www.extrasolar.net/startour.asp?StarCatID=normal&StarID=159
http://www.extrasolar.net/planettour.asp?StarCatId=normal&PlanetId=196