New Planet Discovered! - Most like our own

clark · 2005-06-13 11:49:06

http://www.spaceref.com/news/viewnews.h … ml?id=1031

Researchers speaking today at the National Science Foundation announced the discovery of the smallest extrasolar planet yet found - one that resembles our own planet much more than any other yet discovered.
The planet is between 6 to 9 times the mass of Earth and orbits its host star once every 1.9 days at a distance of 2 million miles. The surface of the planet is hot and has been estimated from observations and calculations to be between 400-700F.
The host star which this planet circles is Gliesse 876, a small red dwarf one third the mass of our sun and is located 15 light years from our solar system
According to one researcher "this is the most Earth like planet discovered since the dawn of history but it is not likely to hold that title for long."
According to astronomer Geoff Marcy, "155 extrasolar planets have been discovered over the past decade. To date all of these planets are gas giants - similar to Jupiter and Saturn with masses 100 to 1000 times that of Earth. Last year we reported two Neptune-class planets. Today we report a new type of planet - much lower than any reported around a sunlike star. It is more similar to Earth than any previously discovered planet. We have no analog like this in our solar system. We do not know its composition - whether it is all rock or some chimera of rock, ice, and a thick atmosphere - perhaps a hybrid of Earth and Uranus."
The discovery of this planet was serendipitous. According to Marcy there were two previously discovered Jupiter-sized planets orbiting this star further out. "These two planets pull on each other and change their orbits notably every year. We were using the Keck telescope to study these two planets and discovered this small planet fortuitously using the Doppler effect." Paul Butler noted: "we would have announced this 3 years ago except for the signal of a third planet."
Marcy went on to note that numerous improvements have been made in use of the Doppler effect. "This technology allows us to measure the speed of a star to an accuracy +/- 1 meter per second - that's human walking speed.

Geoff Marcy put the discovery in context saying: "for the first time we are able to find our planetary kin among the stars".

First post!

Rxke · 2005-06-13 14:55:01

6 to 9 times the mass, that's NOT 6-9 times the size!!!!

this is a *very* small planet, compared to the neptune-sized ones...
fast guesstimation... about twice the size of Earth?

reminds me of the UFO discussion, Cindy mentioning the lack of small planets, heehee....

clark · 2005-06-13 14:56:43

About twice as wide, and hot as hell!

But we are getting better...

Rxke · 2005-06-13 15:08:58

ok, so volume is same (proportional) to mass...
volume is proportional to size (to the power of) 3

so 9= size power 3

size: 2,08 times Earth

or for 6 times the mass= 1,82 times Earth

Woowee! (nice guesstimate of mine, was visual, not mthematical, blush)

Fledi · 2005-06-13 16:42:52

It might be something like a bigger version of Venus with these temperatures.

Commodore · 2005-06-13 18:19:05

A Rocky planet?

So its covered in boxing rings?

Palomar · 2005-06-13 20:19:12

*One out of 155. Will be interesting to see how quickly the ratio might (or might not) change.

called their find the most Earthlike world yet discovered outside our solar system.
While that is technically true, the planet is truly weird by any Earthly standard.
The new world orbits the red-dwarf star Gliese 876 at a distance of only 2 million miles (3.2 million kilometers, or 0.021 astronomical unit) with an orbital period — a "year" — that is only 46 hours long. It's so close to its little star that the star must appear in its sky as a fireball 12° across — some 24 times as wide as the Sun in Earth's sky, or about the size of a tennis ball held at arm's length.

waited until it had enough radial-velocity measurements to make the case "rock-solid, even though the planet may not be solid rock,"

http://skyandtelescope.com/news/article_1530_1.asp]From Sky & Telescope article

-*-

As an aside of sorts, Gliese 876 is a 10th-magnitude star and can be seen with a regular backyard telescope.

Coordinates are right ascension 22h 53m 13s, declination -14d 15' 13" (2000.0)...in the bottom of Aquarius's water bucket currently low in the southeast just before the first light of dawn.

Info in the quote courtesy S & T.

--Cindy

Yang Liwei Rocket · 2005-06-13 21:27:52

*One out of 155. Will be interesting to see how quickly the ratio might (or might not) change.

you mean 1 out of 155 are non Gas-giants Cindy

There might be many more if you chck the web, 55 Cancri was called to have a new class of planets dubbed Super Earth to be discovered and are about the mass of Uranus or Neptune and may be rocky terrestrial worlds with thick atmospheres, a planet orbiting mu Arae with a mass of approximately 14 times that of the Earth and a microlensing event in 96 of a quasar led to a speculation that a 3 Earth mass planet is possibly in the unknown lensing galaxy, between Earth and the quasar, some other newly found planets are small like 15 Earth masses such as the Gliese 436 system. There are pulsar planets, which aren't really extra solar systems as pulsars are unlikely to have what astronomers are looking for in their planet quest but Pulsar 1257-plus12 is thought to have an object about the size of an big asteroid or large comet orbiting it....
http://vo.obspm.fr/exoplanetes/encyclo/ … pulsar.php
our detection methods are getting better all the time

Palomar · 2005-06-14 04:10:35

*One out of 155. Will be interesting to see how quickly the ratio might (or might not) change.
you mean 1 out of 155 are non Gas-giants Cindy

*Yes. It's what the 1st-posted article says. Everything I've said pertaining to exo-planets recently is based on what professional astronomers are relating in their science articles, nothing more.

An item which may be of additional interest:

http://www.spaceref.com/news/viewsr.htm … 8]Abstract: Observed Properties of Exoplanets...

...Masses, Orbits, Metallicities:

We review the observed properties of exoplanets found by the Doppler technique which has revealed 152 exoplanets to date. We focus on our ongoing 18-year survey of 1330 FGKM type stars at Lick, Keck, and the Anglo-Australian Telescopes carried out with a uniform Doppler precision of 3 m/s. The 104 planets detected in our survey have masses as low as 15 M_Earth orbiting between 0.03 and 5.5 AU. The mass distribution rises toward the lowest detectable masses as dN/dM is proportional to M^-1.1. Nearly all giant planets orbiting within 2 AU of all FGK stars within 30 pc have now been discovered. The distribution of semi-major axes rises from 0.3 -- 3.0 AU (in bins of Delta log a), but remains unknown for larger orbits. Extrapolation suggests that 12% of the FGK stars harbor exoplanets within 20 AU. The median orbital eccentricity is <e>=0.25 (excluding those tidally circularized), lower than previously measured . Planets orbiting beyond 3 AU continue to exhibit non-zero eccentricity, suggesting that the circular orbits of giant planets in our Solar System are unusual. The occurrence rate of ``hot Jupiters'' within 0.1 AU is 1.2$\pm$0.3 %. The probability of occurrence of planets varies as the square of the stellar metal abundance, $P \propto N^2_Fe, ranging from $<$3% for stars of subsolar metallicity to 25% for stars with [Fe/H] > +0.3. Nearly 14% of planet-bearing stars harbor multiple-planet systems, occasionally locked in resonances. Kepler and Corot should measure the occurrence of earth-sized planets. The Space Interferometry Mission (SIM) will detect planets with masses as low as 3 M_ Earth orbiting within 2 AU of nearby stars and will measure masses, orbits and multiplicity. These candidate rocky planets will motivate spectroscopic follow-up by the ``Terrestrial Planet Finder'' and Darwin.}

--Cindy

SpaceNut · 2005-06-14 05:30:47

Well 15 lightyears away is a whole lot closer than looking 100 but that is still 3 time more than the closest star to us

Euler · 2005-06-14 20:58:13

Radial velocity measurement has improved a lot in the last couple of decades. 30 years ago, 1 km/s was state of the art. However, this technique may not improve very much in the future. Apparently stars have internal vibrations of about 1 m/s, so even if the instrumentation improves beyond that point it would be difficult to distinguish the planet's influence from these vibrations. Also, it should be noted that while the Gliesse 876 is probably only 6-9 times as large as Earth, Earth would be about 50-100 times more difficult to detect using this method. This is because planets that are close to their stars cause their stars to undergo a greater change in during each orbit than planets that are far from their stars, so a .5 Earth-mass planet at .25 au is as easy to detect as Earth. In addition, Gliesse 876 is significantly lighter than Sol, meaning that its velocity will change more than a heavier Star's would with planets orbiting at the same distance.

In order to detect planets like Earth, other methods are needed. This http://en.wikipedia.org/wiki/Image:Extr … .png]graph shows the sensitivity of some of methods of finding planets. COROT and Kepler are transit surveys, so even though they are very sensitive they can only detect planets if they pass directly between the star and the telescope. Gravitational microlensing surveys are also very sensitive, but again they rely on luck and are unlikely to find planets around nearby stars. Most of the planets that have been found were found by the radial velocity method, and you can see what 3 m/s and 1 m/s instruments can detect. Astrometry is the oldest detection method, with attempts at finding planets going back 60 years, though the technology has not been good enough for this method to succeed until recently. This is the method that I think is most likely to find Earth-like planets around nearby stars.

Astrometry works by measuring the proper motion of stars. This works best on nearby stars, and the sensitivity decreases in proportion to distance. 3 parsecs is about 10 light-years, so the SIM mission with an angular resolution of 1 microarcsecond would be able to detect an Earth-like planet that is 10 ly away. Unlike the radial velocity method, it is actually easier to detect planets that are far away from their stars than it is to detect planets that are close to their stars(provided that the planet has time to make a complete orbit during the duration of the study).

Eventually, directly imaging planets may also become a good method of finding planets.

srmeaney · 2005-07-21 19:43:54

It has confirmed all our worst fears...we are the first species ot emerge and are therefor obligated to spread the seeds of life across the Universe.

Space Commonwealth Contract for Terraforming and Colonizing our Mars Territories ($50 million billion-Mars Standard Currency).

New Mars Forums

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#1 2005-06-13 11:49:06

Re: New Planet Discovered! - Most like our own

#2 2005-06-13 14:55:01

Re: New Planet Discovered! - Most like our own

#3 2005-06-13 14:56:43

Re: New Planet Discovered! - Most like our own

#4 2005-06-13 15:08:58

Re: New Planet Discovered! - Most like our own

#5 2005-06-13 16:42:52

Re: New Planet Discovered! - Most like our own

#6 2005-06-13 18:19:05

Re: New Planet Discovered! - Most like our own

#7 2005-06-13 20:19:12

Re: New Planet Discovered! - Most like our own

#8 2005-06-13 21:27:52

Re: New Planet Discovered! - Most like our own

#9 2005-06-14 04:10:35

Re: New Planet Discovered! - Most like our own

#10 2005-06-14 05:30:47

Re: New Planet Discovered! - Most like our own

#11 2005-06-14 20:58:13

Re: New Planet Discovered! - Most like our own

#12 2005-07-21 19:43:54

Re: New Planet Discovered! - Most like our own

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