Possible Interiors of the TRAPPIST-1 Exoplanets

Spitzer_ssc2021-02c_1024

spitzer_ssc2021-02c January 28th, 2021

Credit: NASA/JPL-Caltech/R. Hurt (IPAC)

This illustration shows three possible interiors of the seven rocky exoplanets in the TRAPPIST-1 system, based on precision measurements of the planet densities. Overall the TRAPPIST-1 worlds have remarkably similar densities, which suggests they may share the same ratio of common planet-forming elements. The planet densities are slightly lower than those of Earth or Venus, which could mean they contain fractionally less iron (a highly dense material) or more low-density materials, such as water or oxygen.

In the first model (left), the interior of the planet is composed of rock mixed with iron bound to oxygen. There is no solid iron core, which is the case with Earth and the other rocky planets in our own solar system.

The second model shows an overall composition similar to Earths, in which the densest materials have settled to the center of the planet, forming an iron-rich core proportionally smaller than Earths core.

A variation is shown in the third panel, where a larger, denser core could be balanced by an extensive low-density ocean on the planet's surface. However, this scenario can be applied only to the outer four planets in the TRAPPIST-1 system. On the inner three planets, any oceans would vaporize due to the higher temperatures near their star, and a different composition model is required. Since all seven planets have remarkably similar densities, it is more likely that all the planets share a similar bulk composition, making this fourth scenario unlikely but not impossible.

The high-precision mass and diameter measurements of the exoplanets in the TRAPPIST-1 system have allowed astronomers to calculate the overall densities of these worlds with an unprecedented degree of accuracy in exoplanet research. Density measurements are a critical first step in determining the composition and structure of exoplanets, but they must be interpreted through the lens of scientific models of planetary structure.

Provider: Spitzer Space Telescope

Image Source: http://www.spitzer.caltech.edu/images/6860-ssc2021-02c-Possible-Interiors-of-the-TRAPPIST-1-Exoplanets

Curator: Spitzer Space Telescope, Pasadena, CA, USA

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Image Details

Image Type
Artwork
Object Name
TRAPPIST-1
Subject - Milky Way
Planet > Type > Terrestrial
Star > Spectral Type > M

Distance

Universescale1
40 light years
Spitzer_ssc2021-02c_1280
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ID
ssc2021-02c
Subject Category
B.1.1.1   B.3.3.7  
Subject Name
TRAPPIST-1
Credits
NASA/JPL-Caltech/R. Hurt (IPAC)
Type
Artwork
Image Quality
Good
Distance Notes
Facility
Instrument
Color Assignment
Band
Bandpass
Central Wavelength
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
Email
Telephone
Address
1200 E. California Blvd.
City
Pasadena
State/Province
CA
Postal Code
91125
Country
USA
Rights
Publisher
Spitzer Science Center
Publisher ID
spitzer
Resource ID
ssc2021-02c.tif
Metadata Date
2021-01-27
Metadata Version
1.2
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Detailed color mapping information coming soon...

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Universescalefull
40 light years