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Transiting exoplanet discovered
GERMAN astronomers have found a third star in which a planet, somewhat larger than Jupiter, moves in front of its parent star.
This special alignment is useful for astronomers as details of the orientation of the planet’s orbit allows certain parameters to be determined such as the planet’s mass.
The chances that an exoplanet passes in front of its central star as seen from the Earth are small. However, because of the importance of such events astronomers have been searching for stars that experience small dips in brightness that might be exoplanetary transits.
The new exoplanet has the shortest orbital period found so far. Being so close to its star, only 3.5 million km, (2.1 million miles) the hemisphere that faces the star must be extremely hot, meaning the gas-giant planet is losing its atmosphere.
Chance alignment
So-called exoplanets come in different sizes and move in a variety of orbits at different distances from their central star, some are nearly circular, others quite elongated.
Some are five to ten times more massive than the largest planet in our Solar System, Jupiter. The lightest exoplanets known are about half as massive as Saturn, i.e. about 50 times more massive than the Earth.
Last year, a list of 59 such possible cases of stars with transiting planets was announced by the Optical Gravitational Lensing Experiment (OGLE).
The latest star, OGLE-TR-3, is very similar to our Sun, with a temperature of about 5800 deg C (6100 K).
Although there are still uncertainties, the researchers provisionally deduce a mass of the planet about one half of that of Jupiter. The density is found to be about one-quarter of that of water, or one-fifth of that of Jupiter, meaning that the planet is quite big for its mass.
The orbital period, 28 hours 33 minutes, is the shortest known for any exoplanet and the distance between the star and the planet is correspondingly small, only 3.5 million kilometres.
This means that the temperature on the side of the planet facing the star must be very high, of the order of 2000 °C, suggesting that the planet must be losing its atmosphere by evaporation.
The astronomers suggest that it might be possible to observe this exoplanet directly because of its comparatively strong infrared radiation. An attempt will soon be made.
As only the third exoplanet found this way, the new object confirms the impression that a considerable number of stars may possess giant planets in close orbits around them.
Since such planets cannot form so close to their parent star, they must have migrated inwards to the current orbit from a much larger, initial distance. It is not known how this happens.
Birds’ memory
Birds that migrate seem to have better long-term memories than ones that don’t find their way back to the same place year after year.
In what they say may be the first scientific evidence that memory duration is related to migration, a team of German researchers tested the idea and reported their results for Tuesday’s online issue of Proceedings of the National Academy of Science.
The memories of garden warblers, which migrate, were tested against the closely related Sardinian warblers, which do not, by Claudia Mettke-Hofmann and Eberhard Gwinner of the Max Planck Research Center for Ornithology in Andechs, Germany.
Hand-reared birds from both species were left in a pair of attached rooms for 8.5 hours. One of the rooms contained food and the other did not.
After various delays ranging from four days to a year the birds were reintroduced to the rooms, but neither room contained food this time.
For up to a year the migratory garden warblers spent more time checking out the room that had previously contained food, while the Sicilian warblers preferred that room only for about four weeks, and showed no preference after that.
The researchers conclude that migration helps birds develop stronger memories to help find preferred stopover spots and breeding grounds. They note, however, that the experiment involved only two types of bird and the possibility that other factors are involved in the birds memories cannot be excluded.
Space station newcomers
The three residents of the international space station welcomed two newcomers who floated aboard Monday, the start of a five-day hand-over fraught with new challenges in the wake of the Columbia shuttle disaster.
US astronauts Kenneth Bowersox and Donald Pettit and Russian cosmonaut Nikolai Budarin welcomed American Edward Lu and Russian Yuri Malenchenko aboard the space station after their Soyuz TMA-2 capsule docked.
The crew will show Lu and Malenchenko around the station — much changed since the two were there in 2000 — and update their own knowledge of the Russian Soyuz, which they will use to return to Earth.Originally, they were to return in the Atlantis, but the US shuttle fleet has been grounded since the Columbia disintegrated during re-entry on Feb. 1, killing all seven people aboard.
Frederick Gregory, deputy administrator of NASA, said the international space station partnership has demonstrated its ability to overcome “any obstacle on this road to the future.”
The Russian Soyuz became the only ship capable of carrying crews to and from the space outpost, giving it a vital role in keeping the station manned. The Soyuz trip was put together in record time. — Dawn ScienceDotcom Report
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