{"id":11574,"date":"2017-02-15T06:21:50","date_gmt":"2017-02-15T06:21:50","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=11574"},"modified":"2017-02-15T06:21:50","modified_gmt":"2017-02-15T06:21:50","slug":"heart-far-off-star-beats-planet","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/heart-far-off-star-beats-planet\/","title":{"rendered":"The heart of a far-off star beats for its planet"},"content":{"rendered":"

Scientists observe first planet-induced stellar pulsations.<\/strong><\/em><\/span><\/p>\n

\"\"
For the first time, astronomers have observed a star pulsing in response to its orbiting planet. The star, HAT-P-2, pictured, is one of the most massive exoplanets known today. The planet, named HAT-P-2b, tracks its star in a highly eccentric orbit, flying extremely close to and around the star, then hurtling far out before eventually circling back around.
Image courtesy of NASA (edited by MIT News)<\/figcaption><\/figure>\n

CAMBRIDGE, Mass. —\u00a0For the first time, astronomers from MIT and elsewhere have observed a star pulsing in response to its orbiting planet.<\/span><\/p>\n

The star, which goes by the name HAT-P-2, is about 400 light years from Earth and is circled by a gas giant measuring eight times the mass of Jupiter \u2014 one of the most massive exoplanets known today. The planet, named HAT-P-2b, tracks its star in a highly eccentric orbit, flying extremely close to and around the star, then hurtling far out before eventually circling back around.<\/span><\/p>\n

The researchers analyzed more than 350 hours of observations of HAT-P-2 taken by NASA\u2019s Spitzer Space Telescope, and found that the star\u2019s brightness appears to oscillate ever so slightly every 87 minutes. In particular, the star seems to vibrate at exact harmonics, or multiples of the planet\u2019s orbital frequency \u2014 the rate at which the planet circles its star.<\/span><\/p>\n

The precisely timed pulsations have lead the researchers to believe that, contrary to most theoretical model-based predictions of exoplanetary behavior, HAT-P-2b may be massive enough to periodically distort its star, making the star\u2019s molten surface flare, or pulse, in response.\u00a0<\/span><\/p>\n

\u201cWe thought that planets cannot really excite their stars, but we find that this one does,\u201d says Julien de Wit, a postdoc in MIT\u2019s Department of Earth, Atmospheric and Planetary Sciences. \u201cThere is a physical link between the two, but at this stage, we actually can\u2019t explain it. So these are mysterious pulsations induced by the star\u2019s companion.\u201d<\/span><\/p>\n

De Wit is a lead author of a<\/span> paper<\/a> detailing the results, published today in Astrophysical Journal Letters<\/em>.<\/span><\/p>\n

Getting a pulse<\/strong><\/span><\/p>\n

The team came upon the stellar pulsations by chance. Originally, the researchers sought to generate a precise map of an exoplanet\u2019s temperature distribution as it orbits its star. Such a map would help scientists track how energy is circulated through a planet\u2019s atmosphere, which can give clues to an atmosphere\u2019s wind patterns and composition.<\/span><\/p>\n

With this goal in mind, the team viewed HAT-P-2 as an ideal system: Because the planet has an eccentric orbit, it seesaws between temperature extremes, turning cold as it moves far away from its star, then rapidly heating as it swings extremely close.<\/span><\/p>\n

\u201cThe star dumps an enormous amount of energy onto the planet\u2019s atmosphere, and our original goal was to see how the planet\u2019s atmosphere redistributes this energy,\u201d de Wit says.<\/span><\/p>\n

The researchers obtained 350 hours of observations of HAT-P-2, taken intermittently by Spitzer\u2019s infrared telescope between July 2011 and November 2015. The dataset represents one of the largest ever taken by Spitzer, giving de Wit and his colleagues plenty of observations to allow for detecting the incredibly tiny signals required to map an exoplanet\u2019s temperature distribution.<\/span><\/p>\n

The team processed the data and focused on the window in which the planet made its closest approach, passing first in front of and then behind the star. During these periods, the researchers measured the star\u2019s brightness to determine the amount of energy, in the form of heat, transferred to the planet.<\/span><\/p>\n

Each time the planet passed behind the star, the researchers saw something unexpected: Instead of a flat line, representing a momentary drop as the planet is masked by its star, they observed tiny spikes \u2014 oscillations in the star\u2019s light, with a period of about 90 minutes, that happened to be exact multiples of the planet\u2019s orbital frequency.<\/span><\/p>\n

\u201cThey were very tiny signals,\u201d de Wit says. \u201cIt was like picking up the buzzing of a mosquito passing by a jet engine, both miles away.\u201d<\/span><\/p>\n

Lots of theories, one big mystery<\/strong><\/span><\/p>\n

Stellar pulsations can occur constantly as a star\u2019s surface naturally boils and turns over. But the tiny pulsations detected by de Wit and his colleagues seem to be in concert with the planet\u2019s orbit. The signals, they concluded, must not be due to anything in the star itself, but to either the circling planet or an effect in Spitzer\u2019s instruments.<\/span><\/p>\n

The researchers ruled out the latter after modeling all the possible instrumental effects, such as vibration, that could have affected the measurements, and finding that none of the effects could have produced the pulsations they observed.<\/span><\/p>\n

\u201cWe think these pulsations must be induced by the planet, which is surprising,\u201d de Wit says. \u201cWe\u2019ve seen this in systems with two rotating stars that are supermassive, where one can really distort the other, release the distortion, and the other one vibrates. But we did not expect this to happen with a planet \u2014 even one as massive as this.\u201d<\/span><\/p>\n

The team has some theories as to how the planet might be causing its star to pulse. For example, perhaps the planet\u2019s transient gravitational pull is disturbing the star just enough to tip it toward a self-pulsating phase. There are stars that naturally pulse, and perhaps HAT-P-2b is pushing its star toward that state, the way adding salt to a simmering pot of water can trigger it to boil over. De Wit says this is just one of several possibilities, but getting to the root of the stellar pulsations will require much more work.<\/span><\/p>\n

\u201cIt\u2019s a mystery, but it\u2019s great, because it demonstrates our understanding of how a planet affects its star is not complete,\u201d de Wit says. \u201cSo we\u2019ll have to move forward and figure out what\u2019s going on there.\u201d<\/span><\/p>\n

This research was supported, in part, by NASA\u2019s Jet Propulsion Laboratory and Caltech.\u00a0<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Scientists observe first planet-induced stellar pulsations. CAMBRIDGE, Mass. —\u00a0For the first time, astronomers from MIT and elsewhere have observed a star pulsing in response to its orbiting planet. The star, which goes by the name HAT-P-2, is about 400 light years from Earth and is circled by a gas giant measuring eight times the mass […]<\/p>\n","protected":false},"author":6,"featured_media":11575,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,20],"tags":[],"class_list":["post-11574","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research","category-space-news"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0-300x200.jpg",300,200,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",600,400,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",600,400,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",540,360,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",95,63,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",639,426,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",96,64,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2017\/02\/MIT-stellar-pulse_0.jpg",150,100,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Research<\/a> Space\/ AstroPhysics<\/a>","tag_info":"Space\/ AstroPhysics","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/11574","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=11574"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/11574\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/11575"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=11574"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=11574"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=11574"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}