Posted on 10/10/2006 10:06:19 PM PDT by SunkenCiv
This is an artist's concept of a Jupiter-mass planet orbiting the nearby star Epsilon Eridani. Located 10.5 light-years away, it is the closest known exoplanet to our Solar System. The planet is in an elliptical orbit that carries it as close to the star as Earth is from the Sun, and as far from the star as Jupiter is from the Sun. Epsilon Eridani is a young star, only 800 million years old. It is still surrounded by a disk of dust that extends 30 billion kilometers from the star. The disk appears as a linear sheet of reflecting dust in this view because it is seen edge-on from the planet's orbit, which is in the same plane as the dust disk. The planet's rings and satellites are purely hypothetical in this view, but plausible. As a gas giant, the planet is uninhabitable for life as we know it. However, any moons might have conditions suitable for life. Astronomers determined the planet's mass and orbital tilt in 2006 by using Hubble to measure the unseen planet's gravitational pull on the star as it slowly moved across the sky. Evidence for the planet first appeared in 2000 when astronomers measured a tell-tale wobble in the star. Credit: Credit: NASA, ESA, and G. Bacon (STScI)
(Excerpt) Read more at physorg.com ...
Hubble Zeroes in on Nearest Known ExoplanetAstronomers determined the planet's mass and orbital tilt in 2006 by using Hubble to measure the unseen planet's gravitational pull on the star as it slowly moved across the sky. Evidence for the planet first appeared in 2000 when astronomers measured a telltale wobble in the star... The Jupiter-sized world orbits the Sun-like star Epsilon Eridani, which is only 10.5 light-years away (approximately 63 trillion miles). The planet is so close it may be observable by Hubble and large ground-based telescopes in late 2007, when the planet makes its closest approach to Epsilon Eridani during its 6.9-year orbit. The Hubble observations were achieved by a team led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas at Austin. The observations reveal the the planet's true mass, which the team has calculated to be 1.5 times Jupiter's mass. Hubble also found that the planet's orbit is tilted 30 degrees to our line of sight, which is the same inclination as a disk of dust and gas that also encircles Epsilon Eridani. This is a particularly exciting result because, although it has long been inferred that planets form from such disks, this is the first time that the two objects have been observed around the same star.
Newswise
Gosh, it's too bad the HST is washed up and obsolete. ;')
http://hubblesite.org/newscenter/newsdesk/archive/releases/2006/32/
EXCLUSIVE: First Confirmed Picture of a Planet Beyond the Solar System
Space.com | April 1, 2005 | Robert Roy Britt
Posted on 04/01/2005 2:35:44 PM EST by conservativecorner
http://www.freerepublic.com/focus/f-news/1375632/posts
This doesn't prove that planets form from accretion disks. They've simply found a planet in a system with an accretion disk.Quibble -- they've found a planet (a gigantic one) around a star, and a disk of dust and debris around the same star. :')
The planet is in an elliptical orbit that carries it as close to the star as Earth is from the Sun, and as far from the star as Jupiter is from the Sun. Epsilon Eridani is a young star, only 800 million years old. It is still surrounded by a disk of dust that extends 30 billion kilometers from the star.For that matter, the orbit of the planet, along with the lack of proximity to the disk (which is over 18 billion miles from the star), suggests either a capture origin, expulsion, or collision.
"The planet's rings and satellites are purely hypothetical in this view, but plausible."
Something about that bothers me...fake but (potentially) accurate?
Yeah, it's not unlikely that giant, fluffy planets by and large have ring systems, but I found that particular imaginary detail to be misleading.
Disk around AU Microscopii
A Hubble Space Telescope image of the disk of gas and dust surrounding red dwarf star AU Microscopii. Planets may be forming, or already orbiting, within the disk. The image was taken December 9, 2004. Credit: NASA, ESA, J.E. Krist (STScI/JPL); D.R. Ardila (JHU); D.A. Golimowski (JHU); M. Clampin (NASA/Goddard); H.C. Ford (JHU); G.D. Illingworth (UCO-Lick); G.F. Hartig (STScI) and the ACS Science Team
Astronomers Track the Birth of a PlanetOur galactic neighbor, Epsilon Eridani, has long been the target of both scientific and literary speculation. Back in 1960, the star was one of two targets of the very first SETI search – Frank Drake's Project Ozma. A few years later, when Star Trek hit television screens across North America, Epsilon Eridani was designated as the sun of Vulcan, Mr. Spock's home world. Then, in the year 2000, a true planet was detected orbiting Epsilon Eridani – among the first extrasolar planets discovered, and the closest one to Earth. And now, the decades of close observation of the star have yielded a truly remarkable result: the first direct evidence that planets are formed from clouds of gas and dust swirling around young stars... Epsilon Eridani is in some ways very similar to our Sun. Only 10.5 light years away it resides practically in our galactic backyard, and its mass is estimated at 83% of the Sun. The main difference between the two is their age: whereas the Sun has reached the mature middle age of 4.5 billion years, Epsilon Eridani is a sprightly 800 million years old. Because of its youth, Epsilon Eridani is still surrounded by a swirling disk of gas and dust, whereas our Sun had lost its own disk billions of years ago. Nevertheless, according to prevailing models, Epsilon Eridani is old enough for its disk to have given birth to actual planetary companions, and it therefore came as no surprise that just such a planet was discovered orbiting the star in 2000... The authors then observed that the orbital inclination of the planet, as seen from Earth is quite substantial – a full 30 degrees. This result is important for calculating the planet's mass, because it reveals what component of its real motion is seen from Earth as the "back and forth" wobble of the star detectable in spectroscopic measurement. In this case, the mass of the planet turned out to be 1.55 Jupiters, well within the range of planetary masses. But the 30 degree tilt is important for another reason: it very closely matches the known tilt of the protoplanetary disk surrounding Epsilon Eridani. And this means that the giant Jupiter-like planet known as Epsion Eridani_b is very likely the first planet ever detected orbiting within the cloud of gas and dust from which it formed.
by Amir Alexander
Planetary Society
19 October 2006
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