Variable Winds on Hot Giant Exoplanet Help Study of Magnetic Field
by Staff Writers
Tucson AZ (SPX) May 16, 2017
Senior Scientist Tamara M. Rogers of the Planetary Science Institute has discovered that substantial variability in the winds on the hot giant exoplanet HAT-P-7b are due to magnetism, and used those measurements to develop a new method to constrain the magnetic field of such an object.
HAT-P-7b was discovered by NASA's Kepler Mission in 2008. It is nearly 40 percent larger and nearly 80 percent more massive than Jupiter. It orbits its star every couple of days, and is so close that dayside temperature may be 2,200 degrees Kelvin (3,500 degrees Fahrenheit) with a night side 1,000 Kelvin (1,340 degrees Fahrenheit) cooler.
This strong day-night temperature difference drives strong eastward winds in the atmosphere and shifts the hottest temperature away from the point directly beneath the star on the dayside. However, this hot spot shifts significantly over time - even ending up on the west side of the sub-stellar point. This means that the winds are also changing significantly.
"The extreme temperatures of HAT-P-7b ionizes alkali metals such as lithium, sodium, and potassium, which results in the coupling of the atmosphere to a deep-seated magnetic field. Magnetic forces are able to then disrupt the strong eastward winds, leading to variable and even oppositely directed winds," Rogers said.
Rogers used a hydrodynamic model of the atmosphere in combination with a magnetohydrodynamic (MHD) model to reproduce the observed variations in the hot spot location, thereby setting a minimum value for the strength of the magnetic field of this planet at six times that of the Earth.
"Long timeline or multiple epoch observations of hot giant exoplanet phase curves coupled with MHD models of the atmospheres of these planets, can be used to place constraints on the magnetic field strengths of other hot giant exoplanets," Rogers said. "This will provide new insights into dynamo theory, planetary evolution and interpretations of star-planet magnetic interactions."
Research paper: "Constraints on the Magnetic Field Strengths of HAT-P-b and Other Hot Giant Exoplanets," Tamara M. Rogers, 2017 May 15, Nature Astronomy
Pasadena CA (JPL) May 15, 2017
A study combining observations from NASA's Hubble and Spitzer space telescopes reveals that the distant planet HAT-P-26b has a primitive atmosphere composed almost entirely of hydrogen and helium. Located about 437 light-years away, HAT-P-26b orbits a star roughly twice as old as the Sun. The analysis is one of the most detailed studies to date of a "warm Neptune," or a planet that is Nept ... read more
Planetary Science Institute
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.