Amature Astronomer: stars

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Hubble’s New Pictures

Posted by Esse-Jay | Posted in eletromagnetic spectrum, galaxies, hubble space telescope, planets, stars | Posted on 12:43

The first snapshots from the refurbished Hubble showcase the 19-year-old telescope's new vision. Topping the list of exciting new views are colorful multi-wavelength pictures of far- flung galaxies, a densely packed star cluster, an eerie "pillar of creation," and a "butterfly" nebula.

**Butterfly emerges from stellar demise in Planetary Nebula NGC 6302. (Credit: NASA, ESA, and the Hubble SM4 ERO Team)**

With the release of these images, astronomers have declared Hubble a fully rejuvenated observatory. Sen. Barbara A. Mikulski, D-Md., unveiled the images at NASA Headquarters in Washington, D.C., on Sept. 9, 2009.

With its new imaging camera, Hubble can view galaxies, star clusters, and other objects across a wide swath of the electromagnetic spectrum, from ultraviolet to near-infrared light. A new spectrograph slices across billions of light-years to map the filamentary structure of the universe and trace the distribution of elements that are fundamental to life.The telescope's new instruments also are more sensitive to light and can observe in ways that are significantly more efficient and require less observing time than previous generations of Hubble instruments.

NASA astronauts installed the new instruments during the space shuttle servicing mission in May 2009. Besides adding the instruments, the astronauts also completed a dizzying list of other chores that included performing unprecedented repairs on two other science instruments.

**Hubble image - One among the largest ever produced with the Earth-orbiting observatory - shows gives the most detailed view so far of the entire Crab Nebula ever made. (Image credit: NASA, ESA and Jeff Hester (Arizona State University))**

Now that Hubble has reopened for business, it will tackle a whole range of observations. Looking closer to Earth, such observations will include taking a census of the population of Kuiper Belt objects residing at the fringe of our solar system, witnessing the birth of planets around other stars, and probing the composition and structure of the atmospheres of other worlds.

Peering much farther away, astronomers have ambitious plans to use Hubble to make the deepest-ever portrait of the universe in near-infrared light. The resulting picture may reveal never-before-seen infant galaxies that existed when the universe was less than 500 million years old. Hubble also is now significantly more well-equipped to probe and further characterize the behavior of dark energy, a mysterious and little-understood repulsive force that is pushing the universe apart at an ever-faster rate.

Source: JPL, ScienceDaily

Kepler’s Moon Hunt

Posted by Esse-Jay | Posted in concept of planets, earth mass, exomoons, galaxy, jupiter like worlds, kepler, moon, saturn, stars, sun | Posted on 16:16

Since the launch of the NASA Kepler Mission earlier this year, astronomers have been keenly awaiting the first detection of an Earth-like planet around another star. Now, in an echo of science fiction movies a team of scientists led by Dr David Kipping of University College London thinks that they may even find habitable 'exomoons,' too.

**Artist's impression of a hypothetical exomoon in orbit around a Saturn-like planet in another planetary system. (Credit: Dan Durda)**

Kepler's primary mission is to monitor thousands of stars looking for characteristic dips in their brightness as orbiting planets pass in front of them in so-called 'transit' events. The orbiting observatory should be able to time these transits to an extremely high accuracy.
Dr Kipping has already devised a method for detecting exomoons but no-one was sure whether it could really be used with current technology. He and his team have now modelled the properties of the instruments on Kepler, simulating the expected signal strength that a habitable moon would generate. An exomoon's gravity tugs on the planet it orbits, making the planet wobble during its orbit around its host star. The resulting changes in the position and velocity of the planet should be detectable by Kepler through accurate timing of the transits.

The scientists considered a wide range of possible planetary systems and found that a fluffy Saturn-like planet (the ringed world is extremely low in mass for its size) gives the best possible chance for detecting a moon, rather than a denser Jupiter-like world. This is because planets like Saturn are large – blocking out a lot of light as they pass in front of their star – but very light, meaning they will wobble much more than a heavy planet.
If the Saturn-like planet is at the right distance from its star, then the temperature will allow liquid water to be stable on any sufficiently large moons in orbit around it and these could then be habitable. The team found that habitable exomoons down to 0.2 times the mass of the Earth are readily detectable with Kepler. Potentially the observatory could look for Earth-mass habitable moons around 25,000 stars up to 500 light-years away from the Sun. In the whole sky, there should be millions of stars which could be surveyed for habitable exomoons with present technology.

Whether or not such bodies are common in the Galaxy is unknown but astronomers now have the tools and the methodology to find out. Dr Kipping says, "For the first time, we have demonstrated that potentially habitable moons up to hundreds of light years away may be detected with current instrumentation"

'As we ran the simulations, even we were surprised that moons as small as one-fifth of the Earth's mass could be spotted. 'It seems probable that many thousands, possibly millions, of habitable exomoons exist in the Galaxy and now we can start to look for them."

Source: Kipping D. M., Fossey S. J., Campanella G. On the detectability of habitable moons with Kepler-class photometry.

Found planet that shouldn't exist

Posted by Esse-Jay | Posted in constellation, journal nature, planets, solar system, stars, wasp 18 | Posted on 11:34

The find, by an international team including the University of St Andrews, is so bizarre that odds on catching it at this late stage in its life were 1000-1. The 'huge new planet', found orbiting a star 1000 light years away, was discovered by the UK's WASP project, of which St Andrews is a founding member.

Newly-christened WASP-18b, the planet is so massive and so close to its host star that it is almost certain to spiral inwards to its destruction during the lifetime of the star. Researchers from St Andrews are currently calculating the rate at which tidal interactions between star and planet will eventually cause the planet's orbit to decay completely.

St Andrews' physicist, Professor Andrew Collier Cameron said, "This is another bizarre WASP planet discovery. The situation is analogous to the way tidal friction is gradually causing the earth's spin to slow down, and the Moon to spiral away from the earth.

"In this case, however, the spin of the star is slower than the orbit of the planet - so the star should be spinning up, and the planet spiralling in."

WASP-18b is ten times the mass of Jupiter and orbits its star in less than one Earth-day. The new planet belongs to a now-common class of extrasolar planets known as 'hot Jupiters' - massive planets thought to have formed far from their host stars that migrated inwards over time.

The discovery, led by Keele University's Coel Hellier, suggests that WASP-18's parent star is about a billion years old - making the likelihood of observing WASP-18b about one in a thousand.

If the planet's remaining life is as short as predicted, its orbital decay should be measurable within a decade.

Professor Cameron continued, "We don't yet know how long the planet will survive, because we don't understand fully how tides operate on the Sun and other stars. It could be half a million years, or half a billion. But if it's spiralling in quickly, we should be able to see measurable changes in the orbit within ten years."

Provided by University of St Andrews

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Hubble’s New Pictures

Kepler’s Moon Hunt

Found planet that shouldn't exist

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