* Astronomy

Blobrana · L

RE: HD15115

Blobrana · L

Title: Colour Gradients Detected in the HD 15115 Circumstellar Disk
Authors: J.H. Debes, A.J. Weinberger, I. Song
(Version v2)

We report HST/NICMOS coronagraphic images of the HD 15115 circumstellar disk at 1.1\micron. We find a similar morphology to that seen in the visible and at H band--an edge-on disk that is asymmetric in surface brightness. Several aspects of the 1.1\micron data are different, highlighting the need for multi-wavelength images of each circumstellar disk. We find a flattening to the western surface brightness profile at 1.1\micron interior to 2\arcsec (90 AU) and a warp in the western half of the disk. We measure the surface brightness profiles of the two disk lobes and create a measure of the dust scattering efficiency between 0.55-1.65\micron at 1\arcsec, 2\arcsec, and 3\arcsec. At 2\arcsec the western lobe has a neutral spectrum up to 1.1\micron and a strong absorption or blue spectrum >1.1\micron, while a blue trend is seen in the eastern lobe. At 1\arcsec the disk has a red F110W-H colour in both lobes.

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Blobrana · L

A passing star may have plundered matter from a debris disc around a young star and left it lopsided, astronomers say.
About 15% of ordinary stars are thought to have dusty debris discs around them. Such discs are thought to be made of dust created when small comet- or asteroid-like objects collide with one another around their parent stars.

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Blobrana · L

Astronomers using the W. M. Keck Observatory and NASAs Hubble Space Telescope to study disks of debris around stars have found one that is extremely lopsided.

While scientists are accustomed to finding asymmetrical accumulations of dust and larger bodies around stars, the debris disk around a star known as HD 15115 has a needle-like shape.
Astronomers believe the shape of debris disks can be affected by extrasolar planets or nearby stars on very elliptical orbits. Researchers are studying whether the gravity of a star known as HIP 12545, located about 10 light years from HD 15115, is the reason for the needle formation which appears blue when viewed in optical light with Hubble and near-infrared light with Keck.

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Astronomers using the Hubble Space Telescope and W. M. Keck Observatory have found a lopsided debris disk around a young star known as HD 15115. As seen from Earth, the edge-on disk resembles a needle sticking out from the star.
Astronomers think the disk's odd imbalanced look is caused by dust following a highly elliptical orbit about the star. The lopsided disk may have been caused by the gravity of planets sweeping up debris in the disk or by the gravity of a nearby star.
The observations were made by Paul Kalas, James Graham, and Michael P. Fitzgerald, all from the University of California at Berkeley. Their paper appeared in The Astrophysical Journal Letters.

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Credit: NASA, ESA, and P. Kalas (University of California, Berkeley)

Blobrana · L

The sun has some weird next-door neighbours.
Astronomers using the Hubble Space Telescope and the W.M. Keck Observatory on Mauna Kea have produced images of a huge, lopsided disk of debris around a nearby star.
They are calling it the "blue needle" because of the appearance of the disc seen on edge.
About 100 other stars are known to have discs, but the blue needle is "far more asymmetrical" than any of its companions in a nearby collection called the Beta Pictoris Moving Group, a Keck announcement said.

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