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 Structured light and nanomaterials open new ways to tailor light at the nanoscale
23.04.2018 | Academy of Finland

nachricht On the shape of the 'petal' for the dissipation curve
23.04.2018 | Lobachevsky University

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: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>