The W. M. Keck Observatory in Hawaii and NASA’s Hubble Space Telescope have made independent confirmations of an exoplanet orbiting far from its central star. The planet was discovered through a technique called gravitational microlensing. This finding opens a new piece of discovery space in the extrasolar planet hunt: to uncover planets as far from their central stars as Jupiter and Saturn are from our sun. The Hubble and Keck Observatory results will appear in two papers in the July 30 edition of The Astrophysical Journal.
The large majority of exoplanets cataloged so far are very close to their host stars because several current planet-hunting techniques favor finding planets in short-period orbits. But this is not the case with the microlensing technique, which can find more distant and colder planets in long-period orbits that other methods cannot detect.
Microlensing occurs when a foreground star amplifies the light of a background star that momentarily aligns with it. If the foreground star has planets, then the planets may also amplify the light of the background star, but for a much shorter period of time than their host star. The exact timing and amount of light amplification can reveal clues to the nature of the foreground star and its accompanying planets.
“Microlensing is currently the only method to detect the planets close to their birth place,” said team member, Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris. “Indeed, planets are being mostly formed at a certain distance from the central star where it is cold enough for volatile compounds to condense into solid ice grains. These grains will then aggregate and will ultimately evolve into planets.”
The system, cataloged as OGLE-2005-BLG-169, was discovered in 2005 by the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-Up Network (MicroFUN), and members of the Microlensing Observations in Astrophysics (MOA) collaborations—groups that search for extrasolar planets through gravitational microlensing.
The NASA/ESA Hubble Space Telescope and many other telescopes on the ground and in space have been used to obtain the best view yet of a collision that took place between two galaxies when the Universe was only half its current age. The astronomers enlisted the help of a galaxy-sized magnifying glass to reveal otherwise invisible detail.
These new studies of the galaxy have shown that this complex and distant object looks surprisingly like the well-known local galaxy collision, the Antennae Galaxies.
In this picture, which combines views from Hubble and the Keck-II telescope on Hawaii (using adaptive optics), you can see a foreground galaxy that is acting as the gravitational lens. The galaxy resembles how our home galaxy, the Milky Way, would appear if seen edge-on. But around this galaxy there is an almost complete ring — the smeared out image of a star-forming galaxy merger far beyond.
A team of scientists led by astronomers at the University of California, Riverside has used NASA’s Hubble Space Telescope and the W. M. Keck Observatory to uncover the long-suspected underlying population of galaxies that produced the bulk of new stars during the universe’s early years.
The galaxies are the smallest, faintest, and most numerous galaxies ever seen in the remote universe, and were captured by Hubble deep exposures taken in ultraviolet light, and confirmed using the mighty Keck I telescope on the summit of Mauna Kea on the island of Hawaii.
25th magnitude is a lot deeper than amateur attempts at recovery, though the amateur efforts likely covered a great deal more area than Hubble with wider fields of view. Still, there have been no reports of any remains detected by any searcher.
Does this rule out any surviving fragments?
We can’t completely rule out the possibility that something is left of the comet. After all, it was seen after its passage close to the Sun, but disappeared not long after. This material would still exist, but is likely very diffuse gas, dust, and very small pieces spread over an extremely large area. – Zolt Levay, The HubbleSite Blog
I think it is pretty safe to call this comet dead.