* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: Extrasolar Planet Conference


L

Posts: 131433
Date:
16 extrasolar planet candidates
Permalink  
 


NASA's Hubble Space Telescope has discovered 16 extrasolar planet candidates orbiting a variety of distant stars in the central region of our Milky Way galaxy.

Sagittarius
Position (2000): R.A. 17h 59m 00s Dec. -29 ° 12' 00"
Constellation: Sagittarius

The planet bonanza was uncovered during a Hubble survey, called the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). Hubble looked farther than has ever successfully been searched for extrasolar planets. Hubble peered at 180,000 stars in the crowded central bulge of our galaxy 26,000 light-years away or one-quarter the diameter of the Milky Way's spiral disk. The results will appear in the Oct. 5 issue of the journal Nature.

Read more

__________________


L

Posts: 131433
Date:
RE: Extrasolar Planet Conference
Permalink  
 



A seam of stars at the centre of the Milky Way has shown astronomers that an entirely new class of planets closely orbiting distant suns is waiting to be explored, according to a paper published on Thursday.
The finding opens up a new area of investigation for space scientists probing extrasolar planets —planets that orbit stars other than our own, it says.
Astronomers have spotted 202 extrasolar planets since the first was spotted in October 1995.
Their technique is based on the so-called “wobble” method. Under this, the astronomer measures the frequencies of light from the star. There is a telltale oscillation, or wobble, in this light if the star is tugged by a planet.
So far, planets with the shortest orbits, of 1.2-2.5 days, have mainly been found encircling stars that are hot and bright, with a mass at least three-quarters that of our Sun.
An international team of astronomers, using a camera aboard NASA’s Hubble telescope, delved into a zone of the Milky Way known as the “galactic bulge”, thus called because it is rich in stars and in the gas and dust which go to make up stars and planets.
They uncovered the existence of 16 planets in the category of close orbiters, taking between 0.4 and 3.2 days to go around their respective stars. Many of the planets are the size of Jupiter, the largest planet in our Solar System.
Two of the 16 have orbits of less than a day, creating a new category of “ultra-short” orbits.
In addition, the planets generally orbit stars that are somewhat lighter than the typical stars seen in earlier extrasolar discoveries.
The team, led by Kailash Sahu of the Space Telescope Science Institute in Baltimore, Maryland, report their work in Nature, the British weekly science journal.
They believe that any planets which orbited at such a close distance to brighter, hotter stars would be destroyed by solar radiation.
And large Jupiter-sized planets are being spotted at these remarkably close orbits because the star, being of low mass, exerts a relatively low gravitational pull.

Source


__________________


L

Posts: 131433
Date:
Permalink  
 

Title: The Galactic Bulge Deep Field: A Planetary Transit Survey and Very Deep Stellar Mass Function
Authors: Sahu, Kailash

We propose to observe a Galactic bulge field continuously with ACS/WFC over a 7-day period. We will monitor ~167, 000 F, G, and K dwarfs down to V=23, in order to detect transits by orbiting Jovian planets. If the frequency of "hot Jupiters" is similar to that in the solar neighborhood, we will detect over 100 planets, more than doubling the number of extrasolar planets known. For the brighter stars with transits, we will confirm the planetary nature of the companions through radial- velocity measurements using the 8-m VLT. We will determine the metallicities of most of the planet-bearing stars as well as a control sample, through follow-up VLT spectroscopy. The metallicities of the target stars range over more than 1.5 dex, allowing for a determination of the dependence of planet frequency upon metallicity--a crucial element in understanding planet formation. We will be able to discriminate between the equally numerous disk and bulge stars via proper motions. Hence we will determine, for the first time, the frequencies of planets in two entirely different stellar populations. We will also determine for the first time the distribution of planetary radii for extrasolar planets for both these populations. Parallel observations with NICMOS will provide ultra-deep near-infrared images of a nearby bulge field, which will be used to determine the stellar luminosity and mass functions down to the brown-dwarf regime. The data will also be useful for a variety of spinoff projects, including a census of variable stars and of hot white dwarfs in the bulge, and the metallicity distribution of bulge dwarfs.

Source

__________________


L

Posts: 131433
Date:
Permalink  
 

Hubble survey may reveal scores of new planets
The Hubble Space Telescope may have discovered as many as 100 new planets out beyond our solar system orbiting stars in the Milky Way galaxy, astronomers say.

If confirmed, that would double the known population of alien planets since the first one was detected nine years ago, according to Steven Beckwith, the director of the Space Science Telescope Institute in Baltimore, which operates the Hubble.
Astronomers are coming to believe that almost every sunlike star in the galaxy, and probably in the universe, is accompanied by one or more planets like our solar system, vastly increasing the chance that some form of extraterrestrial life could exist.
Hubble's expected harvest of previously unknown planets stems from a sweep of thousands of stars in the dome-like bulge protruding above the flat disk of the Milky Way.
For seven straight days in late February, Kailash Sahu, an astronomer at the Baltimore institute, used the 14-year-old telescope to monitor the amount of light streaming from the brightest stars.
A tiny decrease -- less than a tenth of 1 percent -- in the light was a sign that something, perhaps a planet, was passing in front of the star. A similar phenomenon entranced millions of earthlings when Venus transited the sun June 8, 2004.
Sahu is now employing an older planetary-detection method to confirm that the transiting objects are really planets and not something else, such as dwarf stars or clouds of interstellar gas. Using a large ground-based telescope in Chile, he's looking for small irregularities, or wobbles, in a star's motion that would prove that it's accompanied by one or more planets.
This is the method that's been used since 1995 to spot about 100 extrasolar planets. Three more have been discovered by the new "transit'' technique in the past year.

"If this is confirmed, in seven days we will have doubled the number of planets known in nine years,'' Beckwith earlier this week told a committee of the National Academy of Sciences, which is exploring the future of the Hubble telescope.

He said Sahu already had determined the existence of several new planets from data gathered during the February sweep. At this rate, Beckwith said, the total haul should be about 100.
The Hubble team expects to find 10 to 20 transiting planets among the 100 that are bright enough that their atmospheres can be observed, Beckwith said. All of them are likely to be gas giants like Jupiter or Saturn, much larger than Earth and inhospitable to life as we know it.
NASA is planning telescopes that will be able to detect Earth-size planets and study their atmospheres.
Astronomers believe that other solar systems probably formed much like our own, when a huge cloud of gas and dust collapsed into a swirling "proto-planetary'' disk similar to Saturn's rings. Gravity concentrated the matter at the centre of the disk to form a star. The outlying material clumped into planets, asteroids and comets.
Several such systems containing two or three planets, as well as other proto-planetary disks, have been found around other stars.

Source

__________________


L

Posts: 131433
Date:
Permalink  
 

NASA's Hubble Discovers Extrasolar Planet Across Our Galaxy

NASA will host a science update at 1 p.m. EDT, Wednesday, Oct. 4, to discuss a Hubble Space Telescope discovery of extrasolar planet candidates orbiting a variety of distant stars. The update will be in the NASA Headquarters Auditorium, 300 E Street S.W., Washington.

Panelists:
-- Jennifer Wiseman, Hubble program scientist, NASA Headquarters
-- Kailash Sahu, principal investigator, Hubble Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) project, Space Telescope Science Institute, Baltimore, Md.
-- Mario Livio, co-investigator, Hubble SWEEPS project, Space Telescope Science Institute
-- Alan Boss, Carnegie Institution of Washington

Read more

-- Edited by Blobrana at 23:12, 2006-09-28

__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard