Earthlike planet in Gliese 581 system?

[okiscopey]

http://news.bbc.co.uk/2/hi/science/nature/6589157.stm

Astronomers have found the most Earth-like planet outside our Solar System to date, a world which could have water running on its surface.

The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra.


Scientists made the discovery using the Eso 3.6m Telescope in Chile.
They say the benign temperatures on the planet mean any water there could exist in liquid form, and this raises the chances it could also harbour life.


"We have estimated that the mean temperature of this 'super-Earth' lies between 0 and 40 degrees Celsius, and water would thus be liquid," explained Stephane Udry of the Geneva Observatory, lead author of the scientific paper reporting the result.

[StarKers]

Does this mean we have somewhere to go when this planet dries up?

[Ric]

A very interesting article.

At 20.5 light years we better start planning the trip now, we might need more than the cut lunch and a thermos.

Cheers

[ballaratdragons]

'The Goldilocks Zone'?

Scientists come up with some strange terms!

[Ric]

I got a good chuckle out of that Ken, it's good to see Astronomers with a sense of humour.

Cheers

[[1ponders]]

If it has oceans, imagine the tides it must get with a 15 earth mass planet between it and it's sun. With this planet only having a 13 day year there would be hardly spittin' distance between it and the 15 masser.

It would be a stange planet though. That close to it's paretn star it is most probably tidally locked like our moon. Although the other large inner planet may throw that out of whack now and then :eyepop:

If there is life there it may only be able to survive near the twilight zones.

[DobDobDob]

Here is more on the same story, different website: http://www.sciencedaily.com/releases/2007/04/070424204528.htm (http://www.sciencedaily.com/releases/2007/04/070424204528.htm)
I find this a very significant marker on our search for Earth II.

Of course there will be other better candidates as time passes, but one significant factor would be the age of the sun that the planet is orbiting, it would logically, need to be a good deal younger than ours, as well as have the propensity for liquid water.

[bojan]

More here
http://en.wikipedia.org/wiki/Gliese_581

[okiscopey]

It's mentioned in some reports that this is a variable star. Isn't this a problem for the poor old Earth2-lings?

Looked around for some data on Gliese 581 and found this (definitive?) source, but still no info on the magnitude variability.

http://www.stellar-database.com/Scripts/ (http://www.stellar-database.com/Scripts/search_star.exe?Catalog=Gl&CatNo=581)
search_star.exe?Catalog=Gl&CatNo=581 (http://www.stellar-database.com/Scripts/search_star.exe?Catalog=Gl&CatNo=581)

[[1ponders]]

Here is the original paper reporting the exoplanet.
http://exoplanet.eu/papers/udry_terre_HARPS-1.pdf

[[1ponders]]

A couple more from the observatory that was part of the discovery
http://obswww.unige.ch/exoplanets/gl581.html
http://vo.obspm.fr/exoplanetes/encyclo/star.php?st=Gl+581

[[1ponders]]

Here is the original press release to ESO by the discovery group from Geneva

http://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.html

[okiscopey]

Hmmm. Looks like this variable isn't very variable. This paper reports that Gl 581 varies by less than '6mmag'.

Anyone have any idea what a 'mmag' is? Is it a millimagnitude?!?

[[1ponders]]

mmag = millimagnitude (http://vizier.u-strasbg.fr/cgi-bin/Unit?mmag)

[[1ponders]]

It depends on the type of variablility. For this type of star it could not be any of the catastrophic large scale variability scenarios that occur with more massive stars. It might be a problem if it was a flare star (http://en.wikipedia.org/wiki/Flare_star), which is probably the only type of catastrophic variability available to a M class star.

It may be as simple as the type of variability that afflicts our own sun. (Yes our sun comes under the category or a variable star). Sunspots cause our sun to vary it's solar flux over time which is classed as a form of variability (http://earthobservatory.nasa.gov/Study/VariableSun/).

So it just might be nice and cosy there after all. ;) Except for my point above about if it is tidally locked. That could make life unpleasant.

[middy]

I hear because of the current water restrictions in QLD, the people of Brisbane will be on the first ship to leave ......... along with all the hairdressers and telephone sanitizers. :rofl:

[DobDobDob]

Not to mention the housemates from Big Brother :whistle:

[casstony]

It's always nice to see 'space news' broadcast in the TV news. It might excite a few people to think more broadly about where we live and how precarious our existence is.

[StarKers]

I don't know how to waste water. I have one tank, and keep an eye permanently on the water level.

We could probably do alright if we transport the offenders who waste water, along with Peter Beatie and the slow acting polies from Canberra on the First Fleet.

[bojan]

We would be 2.22 times heavier on that planet...

[casstony]

Olympic sports would really not be very exciting on that planet. Brassiere manufacturers would do very well.

[TV John]

Imagine that, Neptune 'like' planet in the sky without the need to peer thru a scope and Marron season only days away, again! All those suns out there and only us? I think not.

[bojan]

Swimming would be quite comfortable, though.. preferred way of life on that planet :)

[Kal]

6mmag variability could be caused by the (at least) two transiting planets perhaps?

[Ingo]

Somebody should try imaging the star and see if you get a moving planet after like 2 days. :thumbsup:

Would it be possible?

[loomberah]

With a half magnitude of variability and the risk of flares from the star, I don't think Goldilocks or anyone else from Earth would find it a very comfortable place to live... maybe in a cave for protection!

cheers, Gordon

[bojan]

I was playing with input of known orbital elements into Celestia...
This is what the planet system should look like from 1.1 AU distance (FOV is 30 degrees) :-)
And the second image is component B transit viewed from the vicinity of component C.

I included the modified file with companion definitions (the original from Celestia website still does not contain components C and D), it should be unzipped on drive C (the unzipped files should be placed in \Celestia\extras\NearbyStars subdirectory)

It is not known if inclination of any of those planets is small enough to enable transits... the values used here are defaults

[gaa_ian]

Does anyone know the SAO or HD catalog #, for Gliese 581 ?
I am trying to find it in Cartes Du Ciel, I am sure i will be asked to point it out at the next observing night !

[loomberah]

from Wikipedia:

It is about two degrees north of Beta Librae (http://en.wikipedia.org/wiki/Beta_Librae), the brightest star in the constellation (http://en.wikipedia.org/wiki/Constellation) Libra (http://en.wikipedia.org/wiki/Libra_%28constellation%29).

and

The name Gliese 581 refers to the Star catalogue (http://en.wikipedia.org/wiki/Star_catalogue) of nearby stars by Wilhelm Gliese (http://en.wikipedia.org/wiki/Wilhelm_Gliese). Other names of this star include BD-07° 4003 (BD catalogue (http://en.wikipedia.org/wiki/Durchmusterung), first known publication) and HO Librae (variable star designation (http://en.wikipedia.org/wiki/Variable_star_designation)).

cheers, Gordon

[gaa_ian]

Thanks Gordon, I was also looking in Wikapedia & found that Info.
Unfortunatly those catalogs are not in my Cartes Du Ceil library.

[loomberah]

I assume it is also known as:

Hipparchos #74995
TYC 5594 1093 1
2UCAC29110263

but the HO Lib position in Guide does not correspond to these, in fact there is no star there at all, the above being about 70" away, but variable star positions are often wrong, so I'm pretty sure the above is it. Surely you must have one of those catalogues?

cheers, Gordon

[bojan]

Gliese catalog is available at the website
http://www.stargazing.net/astropc/external.html

or direct link:
http://astrosurf.com/astropc/cartes/prog/gliese.zip

And, the star is right here.....

[gaa_ian]

Thanks Bojan !

[ispom]

not until we find a planet with such a spectrum, then we have good reason to celebrate :

[ispom]

today's APOD shows us
a picture postcard from the surface of gliese 581 c :)

http://antwrp.gsfc.nasa.gov/apod/ap070502.html

[okiscopey]

It's beautiful. Let's go there!

:lol:

[glenc]

Below is a map showing Gliese 581 in a yellow square.
It is 1d 46m from bet Lib in pa 20 and transits about 1:30 am here.
The map and the following data are from SkyMapPro.

Visual magnitude: 10.57
Spectral type: M5
Distance: 20.4 +/- 0.3 light years
Luminosity: 0.0019 +/- 0.00005 x Sun's luminosity

Hipparcos number: HIP 74995
Hipparcos Catalog Data
Equatorial coordinates (epoch J2000.0, ICRS)
RA: 15h 19m 26.8251s
Dec: -7° 43' 20.208"

Main Mission Variability
Observed magnitude at maximum and minimum luminosities:
Mag at max, Hp: 10.49 (5th percentile)
Mag at min, Hp: 10.60 (95th percentile)
Type of variability: the entry could not be classified as variable or constant with any degree of certainty (eg due to the presence of one or more outliers in the epoch photometry).

[Kal]

Damn! Torvell and Dean beat us! (click this (http://www.artofkaren.blogspot.com/) link to see what the hell I am talking about) :screwy: :rofl:

[Ingo]

We couldn't go there. Human diseases and bacteria would destroy any life form there.

[Ric]

You never know Ingo, the life forms there might have us for Sunday roast.

[ispom]

fear of bacteria I have no many, because even the very most bacteria , transferred the diseases of the animals, cannot harm us anything,
why should extraterrestial bacteria?