How many planet with an water atmosphere have been identified by astronomers?

Doomed planet may have been drenched in water BY KEITH COOPER ASTRONOMY NOW A small exoplanet full of water may have been swallowed up by a dead white dwarf star, according to anomalous readings of hydrogen in the star’s helium-rich atmosphere. This is the possible conclusion put forward by a team of astronomers based in the United States and the UK, and would be a sure sign that water is present in some form deep within sizeable planetary bodies around other stars. Img

/img The white dwarf in question, called GD 362 and located 150 light years away in the constellation Hercules, has been in the news ever since odd amounts of heavy elements were discovered in its atmosphere in 2004, followed a year later by the detection of a ring of broken-up asteroids encircling it.It is easier to understand this ring when you consider what a white dwarf is: the final evolutionary step of a Sun-like star, after its hydrogen fuel in its core has run out and it has swollen into a red giant, before ejecting its outer layers to, leaving behind its helium-rich core in the shape of a white dwarf.

During the red giant phase, the star engulfs and destroys its innermost planets, and disrupts the orbits of outlying bodies. So what we see today in the GD 362 system is a dead solar system. The heavy elements found in GD 362’s atmosphere are believed to have come from a large rocky body that fragmented and was pulled in by the white dwarf’s gravity.

The new observations using the European Space Agency’s XMM-Newton X-ray observing spacecraft and NASA’s infrared Spitzer Space Telescope, described in a paper available on the Astro-ph website, have now found an over-abundance of the lightest element in GD 362’s atmosphere: hydrogen. The hydrogen in question amounts a hundredth of the total mass of Earth. This could be explained if an object, at least as massive as Jupiter’s moon Callisto and possibly as massive as Mars, and containing more water (the source of the hydrogen) deep inside it than even Earth does, was ripped apart by the white dwarf’s gravity and the remnants pulled in by the dead star.

However, this was unlikely to be the destruction of an Earth-like planet with oceans, says one of the researchers, Jay Farihi of the University of Leicester. €œIf it had surface water, it was all evaporated during the giant phase of the host star,â€? Farihi told Astronomy Now.

€œThis makes it unlikely, but not impossible, to have retained internal water. Also, to be in the ‘Goldilocks Zone’ close to a star where liquid water temperatures are maintained makes a planet a candidate for being engulfed and destroyed during the giant phase, prior to the star becoming a white dwarf. €?

Instead, Farihi suspects it may have been an object similar in structure to Europa or Callisto, which are moons suspected to contain oceans deep underground. Or perhaps a Mars-like world that dried up on the surface but retained a large amount of water underground would be a plausible explanation. The alternative is that around a 100 water-rich asteroids the size of Ceres – our Solar System’s largest asteroid – crashed into the white dwarf, but would a solar system contain so many asteroids of that size?

One hundred Ceres-sized objects would contain more mass than our Solar System’s entire asteroid belt put together, but there is evidence of sufficiently large enough belts around other stars, such as zeta Leporis, which may have an asteroid belt weighing in at 4 x 10^23 kilograms, compared to 2 x 10^21 kilograms for our Solar System.To prove it either way, it would be necessary to show whether the hydrogen and heavy elements came from the same object or many different ones. €œIf we were able to show the hydrogen we see was accreted from the same parent body as the metals, it would be an unambiguous detection of extra-solar watery rocks,â€? Says Farihi.

It would be ironic should a doomed planet prove a boon to astronomers searching for habitable worlds containing water. The other researchers include Michael Jura and Ben Zuckerman of the University of California, Los Angeles, and Michael P Muno from Caltech. To see a video of Jay Farihi talking about heavy elements detected in the atmospheres of white dwarfs during April’s European Week of Astronomy and Space Science at the University of Hertfordshire Flagstaff, Ariz.

€“ For the first time, water has been identified in the atmosphere of an extrasolar planet. Through a combination of previously published Hubble Space Telescope measurements and new theoretical models, Lowell Observatory astronomer Travis Barman has found strong evidence for water absorption in the atmosphere of transiting planet HD209458b. This result was recently accepted for publication in the Astrophysical Journal (http://lanl.arxiv.org/abs/0704.1114).

"We now know that water vapor exists in the atmosphere of one extrasolar planet and there is good reason to believe that other extrasolar planets contain water vapor," said Barman. Water vapor (or steam) has been expected to be present in the atmospheres of nearly all of the known extrasolar planets, even those that orbit closer to their parent star than Mercury is to our Sun. For the majority of extrasolar planets, their close proximity to their parent star has made detecting water and other compounds difficult.

The identification reported here takes advantage of the fact that HD209458b, as seen from Earth, passes directly in front of its star every three and half days.As a planet passes in front of a star, its atmosphere blocks a different amount of the starlight at different wavelengths. In particular, absorption by water in the atmosphere of a giant planet makes the planet appear larger across a specific part of the infrared spectrum compared to wavelengths in the visible spectrum. An analysis of visible and infrared Hubble data carried out last year by Harvard student Heather Knutson made possible a direct comparison to new theoretical models developed by Barman at Lowell Observatory.

This ultimately led to the identification of water absorption in a planet 150 light years from Earth. €œIt is encouraging that theoretical predictions of water in extrasolar planets seem to agree reasonably well with observations,â€? Said Barman.

This research was supported by NASA’s Origins of Solar System program. About Lowell Observatory Lowell Observatory is a private, non-profit research institution founded in 1894 by Percival Lowell. The Observatory has been the site of many important findings including the discovery of the large recessional velocities (red-shift) of galaxies by Vesto Slipher in 1912-1914 (a result that led ultimately to the realization the universe is expanding), and the discovery of Pluto by Clyde Tombaugh in 1930.

Today, Lowell's 19 astronomers use ground-based telescopes around the world, telescopes in space, and NASA planetary spacecraft to conduct research in diverse areas of astronomy and planetary science. Lowell Observatory currently has four research telescopes at its Anderson Mesa dark sky site east of Flagstaff, Arizona, and is building a 4-meter class research telescope, the Discovery Channel Telescope, in partnership with Discovery Communications, Inc.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.