Several Jupiter sized planets found to have only weak Earth like gravity

May 02, 2007
Several Jupiter sized planets found to have only weak Earth like gravity

Astrophysicists at the University of Warwick have found that several Jupiter sized gas giants beyond our solar system have surface gravities much closer in strength to Earth than the intense gravity of Jupiter.

The University of Warwick team , Dr John Southworth, Dr Peter Wheatley and Giles Sams are the first people to calculate accurate measures of the surface gravity of all 14 known gas giant planets beyond our solar system that can be observed transiting (moving across the face of) their star.

They created a new method which enabled the Warwick researchers to deduce the surface gravity of all 14 of these gas giants using a technique which is both simpler and ten times more accurate than an older method that had only produced a rough estimate for just one of the gas giants - HD 209458.

All but one of these 14 known gas giant planets that can be seen transiting their star have a planetary radius bigger than Jupiter. Intriguingly the one older surface gravity estimate available, for HD 209458, suggested it had a surface gravity of only 9.43 to 9.7 ms-2. Despite being bigger than Jupiter this would give it a surface gravity closer to Earth’s at 9.8 ms-2 or our own solar system’s smaller gas giants (Saturn 8.96 ms-2, Uranus 8.69 ms-2 and Neptune 11.15 ms-2) rather than Jupiter at 24.79 ms-2.

On carrying out their more accurate measurement of all 14 of these gas giants the Warwick team have discovered that the surface gravity of HD 209458 is not an anomaly. Despite all but one of the gas giants (HD 149026) being bigger than Jupiter all but one of them turned out to have surface gravities that are much lower than Jupiter’s. Only OGLE-TR-113 was found to have a surface gravity higher than Jupiter’s.

In fact they found that 4 of these planets actually have surface gravities close to or lower than that of Earth’s or our own solar system’s "smaller" gas giants rather than Jupiter’s much more intense gravity. A further 4 had surface gravities around half to two thirds that of Jupiter’s. For the planet for which there was already a rough estimate of surface gravity (HD209458b) they actually found an even lower surface gravity of 9.28 ms-2 (error factor of plus or minus 0.15 ms-2).

University of Warwick researcher John Southworth said: "This research gives us a sense of the sheer variety of types of planet to be found beyond our Solar System. An understanding of the surface gravity of these worlds also gives us a clearer picture of the rate of in the evaporation of planetary atmospheres."

Full paper online at uk.arxiv.org/PS_cache/arxiv/pd… 0704/0704.1570v1.pdf

Source: University of Warwick

Explore further: Astrophysicists offer new research, tool for identifying habitable zones

add to favorites email to friend print save as pdf

Related Stories

Why is Venus so horrible?

Dec 19, 2014

Venus sucks. Seriously, it's the worst. The global temperature is as hot as an oven, the atmospheric pressure is 90 times Earth, and it rains sulfuric acid. Every part of the surface of Venus would kill you ...

The RV Investigator's role in marine science

Dec 12, 2014

We know more about the surface of the moon than we do about our deepest oceans, and only 12% of the ocean floor within Australia's Exclusive Economic Zone has so far been mapped.

How was the Earth formed?

Dec 10, 2014

Just how did the Earth—our home and the place where life as we know it evolved—come to be created in the first place? In some fiery furnace atop a great mountain? On some divine forge with the hammer ...

The dark fingers of the solar atmosphere

Dec 08, 2014

The Sun is bubbling, forming mysterious finger-like plasma structures in its gaseous envelope, the corona. A German-American team headed by the Max Planck Institute for Solar System Research has now succeeded ...

Recommended for you

Image: Multicoloured view of supernova remnant

13 hours ago

Most celestial events unfold over thousands of years or more, making it impossible to follow their evolution on human timescales. Supernovas are notable exceptions, the powerful stellar explosions that make ...

Ultra-luminous X-ray sources in starburst galaxies

13 hours ago

Ultra-luminous X-ray sources (ULXs) are point sources in the sky that are so bright in X-rays that each emits more radiation than a million suns emit at all wavelengths. ULXs are rare. Most galaxies (including ...

When a bright light fades

13 hours ago

Astronomer Charles Telesco is primarily interested in the creation of planets and stars. So, when the University of Florida's giant telescope was pointed at a star undergoing a magnificent and explosive death, ...

Image: Horsehead nebula viewed in infrared

14 hours ago

Sometimes a horse of a different color hardly seems to be a horse at all, as, for example, in this newly released image from NASA's Spitzer Space Telescope. The famous Horsehead nebula makes a ghostly appearance ...

The Milky Way's new neighbour

14 hours ago

The Milky Way, the galaxy we live in, is part of a cluster of more than 50 galaxies that make up the 'Local Group', a collection that includes the famous Andromeda galaxy and many other far smaller objects. ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.