Cracking the Code of Faraway Worlds: Atmosphere of Planet HD209458b

Spitzer_ssc2007-04a_1024

spitzer_ssc2007-04a February 21st, 2007

Credit: NASA/ JPL-Caltech/J. Richardson (Goddard Space Flight Center)

This infrared data from NASA's Spitzer Space Telescope called a spectrum tells astronomers that a distant gas planet, a so-called "hot Jupiter" called HD 209458b, might be smothered with high clouds. It is one of the first spectra of an alien world.

A spectrum is created when an instrument called a spectrograph cracks light from an object open into a rainbow of different wavelengths. Patterns or ripples within the spectrum indicate the presence, or absence, of molecules making up the object.

Astronomers using Spitzer's spectrograph were able to obtain infrared spectra for two so-called "transiting" hot-Jupiter planets using the "secondary eclipse" technique. In this method, the spectrograph first collects the combined infrared light from the planet plus its star, then, as the planet is eclipsed by the star, the infrared light of just the star. Subtracting the latter from the former reveals the planet's own rainbow of infrared colors.

When astronomers first saw the infrared spectrum above, they were shocked. It doesn't look anything like what theorists had predicted. For example, theorists thought there'd be signatures of water in the wavelength ranges of 8 to 9 microns. The fact that water is not detected might indicate that it is hidden under a thick blanket of high, dry clouds.

In addition, the spectrum shows signs of silicate dust tiny grains of sand in the wavelength range of 9 to 10 microns. This suggests that the planet's skies could be filled with high clouds of dust unlike anything seen in our own solar system.

There is also an unidentified molecular signature at 7.78 microns. Future observations using Spitzer's spectrograph should be able to determine the nature of the mysterious feature.

This spectrum was produced by Dr. Jeremy Richardson of NASA's Goddard Space Flight Center, Greenbelt, Md. and his colleagues. The data were taken by Spitzer's infrared spectrograph on July 6 and 13, 2005.

Provider: Spitzer Space Telescope

Image Source: http://www.spitzer.caltech.edu/images/1751-ssc2007-04a-Cracking-the-Code-of-Faraway-Worlds-Atmosphere-of-Planet-HD209458b

Curator: Spitzer Space Telescope, Pasadena, CA, USA

Image Use Policy: Public Domain

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Image Details

Image Type
Chart
Object Name
HD 209458b
Subject - Milky Way
Planet > Type > Gas Giant
Planet > Feature > Atmosphere
Planet > Special Cases > Hot Jupiter

Distance

Universescale1
153 light years

Color Mapping

  Telescope Spectral Band Wavelength
Spitzer (IRS) Infrared -
Spectrum plotted between 7.5 and 13 microns
Spitzer_ssc2007-04a_1280
×
ID
ssc2007-04a
Subject Category
B.1.1.2   B.1.2.2   B.1.3.2  
Subject Name
HD 209458b
Credits
NASA/ JPL-Caltech/J. Richardson (Goddard Space Flight Center)
Type
Chart
Image Quality
Good
Distance Notes
Distance taken from Fast Facts.
Facility
Spitzer
Instrument
IRS
Color Assignment
Band
Infrared
Bandpass
Central Wavelength
Start Time
Integration Time
Dataset ID
Notes
S
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
Public Domain
Publisher
Spitzer Science Center
Publisher ID
spitzer
Resource ID
ssc2007-04a.tif
Metadata Date
2011-09-06
Metadata Version
1.1
×

 

Detailed color mapping information coming soon...

×
Universescalefull
153 light years

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