Using the unique observing capabilities of NASA’s Hubble Space Telescope, astronomers have produced the most detailed picture so far of an edge-on disk around the nearby star Beta Pictoris.
Comparing Hubble images of the gas-and-dust disk encircling the young star Beta Pictoris taken in 1997 and 2012, astronomers find that the dust distribution has barely changed over 15 years despite the fact that the entire structure is orbiting the star like a carousel. Image credit: NASA / ESA / D. Apai, University of Arizona, Tucson / G. Schneider, University of Arizona, Tucson.
Beta Pictoris is a young star located approximately 63 light-years away from Earth.
It is estimated to be only 20 million years old and is known to host a gas giant, Beta Pictoris b (discovered in 2008, the exoplanet is more than 16 times larger and 3,000 times more massive than Earth).
The star also has a circumstellar disk of gas and dust that could, in time, evolve into a torus of icy bodies much like the Kuiper Belt found in our own Solar System.
The disk is easily seen because it is tilted edge-on and is especially bright due to a very large amount of starlight-scattering dust.
The new visible-light image from Hubble traces the disk closer to Beta Pictoris to within about 1 billion km of the star, which is inside the radius of Saturn’s orbit about the Sun.
When comparing this image to Hubble images taken in 1997, astronomers find that the disk’s dust distribution has barely changed over 15 years despite the fact that the entire structure is orbiting the star like a carousel.
This means the disk’s structure is smoothly continuous in the direction of its rotation on the timescale, roughly, of the accompanying planet’s orbital period.
Though nearly all of the 24 known light-scattering circumstellar disks have been viewed by Hubble to date, Beta Pictoris is the first and best example of what a young planetary system looks like.
One thing astronomers recently have learned about circumstellar disks is that their structure, and amount of dust, is incredibly diverse and may be related to the locations and masses of planets in those systems.
“The Beta Pictoris disk is the prototype for circumstellar debris systems, but it may not be a good archetype,” said Dr Glenn Schneider of the University of Arizona, Tucson, a co-author of the paper to be published in the Astrophysical Journal (arXiv.org preprint).
For one thing, the Beta Pictoris disk is exceptionally dusty. This may be due to recent major collisions among unseen planetary-size and asteroid-size bodies embedded within it.
In particular, a bright lobe of dust and gas on the southwestern side of the disk may be the result of the pulverization of a Mars-size body in a giant collision.
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Daniel Apai et al. 2015. The Inner Disk Structure, Disk-Planet Interactions, and Temporal Evolution in the Beta Pictoris System: A Two-Epoch HST/STIS Coronagraphic Study. ApJ, in press; arXiv: 1501.03181
