Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First Search in Stellar Graveyard Yields Two Possible Planets

14.01.2005


Astronomers are announcing today the first results of a search for extrasolar planets and brown dwarfs in an unlikely place--the stellar graveyard. The report, titled "Searching for Extrasolar Planets in the Stellar Graveyard," is being presented at the American Astronomical Society meeting in San Diego, California, by John Debes, a graduate student at Penn State; Steinn Sigurdsson, associate professor of astronomy and astrophysics at Penn State University; Bruce Woodgate, of the NASA Goddard Space Flight Center, and their collaborators. These results are particularly interesting because they answer some questions about the presence of planets around stars that are more massive than the Sun.


Shown here is one of the 20 target white dwarfs of our survey. The white dwarf is at the center of the image and has been masked out. North is up and east is to the left. Nearby to the east is a candidate companion (circled), which if associated would be a massive planet or low mass brown dwarf. It needs further observations to confirm or refute its association with the white dwarf.



The research team found two candidate planets in its survey of 20 dead stars--white dwarfs at distances between 24 and 220 lightyears--with three telescopes: the Near-Infrared Camera and Multi-Object Spectrograph on the Hubble Space Telescope, the Canada France Hawaii 3.6-meter (150-inch) Telescope, and the Gemini North 8-meter (300-inch) Telescope. White dwarfs are small, dense, Earth-sized objects that are the leftover corpse of a star that has run out of enough fuel to shine brightly but was once as massive as--or several times more massive than--the Sun. The researchers had calculated that they should be able to detect planets with a mass 10 times that of Jupiter if any were present around most of the white dwarfs, and as small as five times the mass of Jupiter around a few of them, but they detected only two promising candidate planets among the 20 white dwarfs they studied. "You have to be careful with a candidate planet because it often is just a background object," says Sigurdsson. "Since all of our candidates are incredibly faint, we cannot obtain spectra for them to identify whether they are a planet, a brown dwarf, or a background galaxy."

To determine whether the candidates are planets, the Sigurdsson team now plans to take two snapshots of each over a period of several months to a year. "Each target white dwarf moves across the sky about 1/3000 of the diameter of the full moon every year, whereas background objects do not appear to move at all," Debes explains, "so if a candidate moves with the white dwarf that would show that the two are physically associated and the candidate is a planet in orbit around the white dwarf."


The team earlier had detected three candidate planets that they found to be background objects after taking a second image. "If the two remaining candidates also are background objects, that discovery would indicate the frequency of planets around white dwarfs is quite small, though a larger sample of white dwarfs must be studied to more accurately gauge their frequency," Sigurdsson explains.

Because it is nearly impossible with current telescopes to see a planet around a nearby star as bright as the Sun, Sigurdsson’s team searched around near-by white dwarfs, whose dim glow is much less likely to obscure a companion planet. A white dwarf is up to thousands of times dimmer than the Sun and the contrast between it and a planet several times Jupiter’s mass is about a factor of ten thousand less. "If we could find such a planet, then we can use the evidence it provides, like forensic investigators, to tell what the planetary system was like when the star was alive," Debes says.

The research is part of an intense race to take the first "photograph" of an extrasolar planet. Astronomers seek to compare the picture of an extrasolar planet with various theories about how such planets should look. This comparison will help reveal how the solar system formed and how frequent life may be in the Milky Way galaxy. Further discoveries are expected when larger and more sensitive telescopes are built that can better detect Jupiter-size planets.

This research was supported by the Penn State Astrobiology Research Center and the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #9834.

Barbara K. Kennedy | EurekAlert!
Further information:
http://www.psu.edu

More articles from Physics and Astronomy:

nachricht Taking a spin on plasma space tornadoes with NASA observations
20.11.2017 | NASA/Goddard Space Flight Center

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Carefully crafted light pulses control neuron activity

20.11.2017 | Life Sciences

SYSTEMS INTEGRATION 2018 in Switzerland focuses on building blocks for industrial digitalization

20.11.2017 | Trade Fair News

Heavy nitrogen molecules reveal planetary-scale tug-of-war

20.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>