Fomalhaut

Spitzer_ssc2003-06i3_1024

spitzer_ssc2003-06i3 December 18th, 2003

Credit: NASA/JPL-Caltech/K. Stapelfeldt (JPL)

The NASA Spitzer Space Telescope has obtained the first infrared images of the dust disc surrounding Fomalhaut, the 18th brightest star in the sky. Planets are believed to form from such a flattened disc-like cloud of gas and dust orbiting a star very early in its life. The Spitzer telescope was designed in part to study these circumstellar discs, where the dust particles are so cold that they radiate primarily at infrared wavelengths. Located in the constellation Piscis Austrinus, the parent star and its putative planetary system are found at a distance of 25 light-years.

Twenty years ago, the Infrared Astronomical Satellite, the first orbiting infrared telescope, detected much more infrared radiation coming from Fomalhaut than was expected for a normal star of this type. The dust is presumed to be debris left over from the formation of a planetary system. However, the satellite did not have adequate spatial resolution to image the dust directly. Subsequent measurements with sub-millimeter radio telescopes suggested that Fomalhaut is surrounded by a huge dust ring 370 astronomical units (an astronomical unit is the average distance between the Sun and Earth), or 34 billion miles (56 billion kilometers) in diameter. This corresponds to a size of nearly five times larger than our own solar system. Moreover, the sub-millimeter observations (far right image) revealed that the ring was inclined 20 degrees from an edge-on view.

The new images obtained with the multiband imaging photometer onboard Spitzer confirm this general picture, while revealing important new details of Fomalhaut's circumstellar dust. The 70-micron data (red) clearly shows an asymmetry in the dust distribution, with the southern lobe one-third brighter than the northern. Such an unbalanced structure could be produced by a collision between moderate-sized asteroids in the recent past (releasing a localized cloud of dust) or by the steering effects of ring particles by the gravitational influence of an unseen planet.

At 24 microns (green), the Spitzer image shows that the center of the ring is not empty. [Note that an image of a reference star was subtracted from the Fomalhaut image to reveal the faint disc emission.] Instead, the 'doughnut hole' is filled with warmer dust that extends inward to within at least 10 astronomical units of the parent star. This warm inner disc of dust occupies the region that is most likely to be occupied by planets and may be analogous to our solar system's 'zodiacal cloud' -- but with considerably more dust. One possible explanation for this warmer dust is that comets are being nudged out of the circumstellar ring by the gravitational influence of massive planets. These comets then loop in toward the central star, releasing dust particles just as comets do in our own solar system.

Provider: Spitzer Space Telescope

Image Source: http://www.spitzer.caltech.edu/images/1104-ssc2003-06i3-Fomalhaut-at-24-70-microns

Curator: Spitzer Space Telescope, Pasadena, CA, USA

Image Use Policy: http://www.spitzer.caltech.edu/info/18-Image-Use-Policy

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Image Details

Image Type
Observation
Object Name
Fomalhaut alpha PsA HD 216956
Subject - Milky Way
Star > Circumstellar Material > Disk > Debris

Distance

Universescale1
25 light years

Color Mapping

  Telescope Spectral Band Wavelength
Green Spitzer (MIPS) Infrared (Mid-IR) 24.0 µm
Orange Spitzer (MIPS) Infrared (Far-IR) 70.0 µm
Spectrum_ir1
Green
Orange
Spitzer_ssc2003-06i3_1280
×
ID
ssc2003-06i3
Subject Category
B.3.7.2.3.  
Subject Name
Fomalhaut, alpha PsA, HD 216956
Credits
NASA/JPL-Caltech/K. Stapelfeldt (JPL)
Release Date
2003-12-18
Lightyears
25
Redshift
Reference Url
http://www.spitzer.caltech.edu/images/1104-ssc2003-06i3-Fomalhaut-at-24-70-microns
Type
Observation
Image Quality
Good
Distance Notes
Distance taken from Fast Facts.
Facility
Spitzer, Spitzer
Instrument
MIPS, MIPS
Color Assignment
Green, Orange
Band
Infrared, Infrared
Bandpass
Mid-IR, Far-IR
Central Wavelength
24000, 70000
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
Equinox
Reference Value
Reference Dimension
Reference Pixel
Scale
Rotation
Coordinate System Projection:
Quality
FITS Header
Notes
Creator (Curator)
Spitzer Space Telescope
URL
http://www.spitzer.caltech.edu
Name
Spitzer Space Telescope
Email
Telephone
Address
1200 E. California Blvd.
City
Pasadena
State/Province
CA
Postal Code
91125
Country
USA
Rights
http://www.spitzer.caltech.edu/info/18-Image-Use-Policy
Publisher
Spitzer Science Center
Publisher ID
spitzer
Resource ID
ssc2003-06i3.tif
Metadata Date
2012-10-11
Metadata Version
1.1
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Detailed color mapping information coming soon...

×
Universescalefull
25 light years

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