MSGID: 1:317/3 6476cd84   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Astronomers discover last three planets Kepler telescope observed before   
   going dark    
      
     Date:   
         May 30, 2023   
     Source:   
         Massachusetts Institute of Technology   
     Summary:   
         With the help of citizen scientists, astronomers discovered what   
         may be the last three planets that the Kepler Space Telescope saw   
         before it was retired.   
      
      
         Facebook Twitter Pinterest LinkedIN Email   
      
   ==========================================================================   
   FULL STORY   
   ==========================================================================   
   More than 5,000 planets are confirmed to exist beyond our solar   
   system. Over half were discovered by NASA's Kepler Space Telescope,   
   a resilient observatory that far outlasted its original planned   
   mission. Over nine and a half years, the spacecraft trailed the Earth,   
   scanning the skies for periodic dips in starlight that could signal the   
   presence of a planet crossing in front of its star.   
      
   In its last days, the telescope kept recording the brightness of stars   
   as it was running out of fuel. On Oct. 30, 2018, its fuel tanks depleted,   
   the spacecraft was officially retired.   
      
   Now, astronomers at MIT and the University of Wisconsin at Madison,   
   with the help of citizen scientists, have discovered what may be the   
   last planets that Kepler gazed upon before going dark.   
      
   The team combed through the telescope's last week of high-quality data   
   and spotted three stars, in the same part of the sky, that appeared to   
   dim briefly.   
      
   The scientists determined that two of the stars each host a planet,   
   while the third hosts a planet "candidate" that has yet to be verified.   
      
   The two validated planets are K2-416 b, a planet that is about 2.6 times   
   the size of the Earth and that orbits its star about every 13 days,   
   and K2-417 b, a slightly larger planet that is just over three times   
   Earth's size and that circles its star every 6.5 days. For their size and   
   proximity to their stars, both planets are considered "hot mini-Neptunes   
   ." They are located about 400 light years from Earth.   
      
   The planet candidate is EPIC 246251988 b -- the largest of the three   
   worlds at almost four times the size of the Earth. This Neptune-sized   
   candidate orbits its star in around 10 days, and is slightly farther away,   
   1,200 light years from Earth.   
      
   "We have found what are probably the last planets ever discovered   
   by Kepler, in data taken while the spacecraft was literally running   
   on fumes," says Andrew Vanderburg, assistant professor of physics   
   in MIT's Kavli Institute for Astrophysics and Space Research. "The   
   planets themselves are not particularly unusual, but their atypical   
   discovery and historical importance makes them interesting."  The team   
   has published their discovery today in the journal Monthly Notices of   
   the Royal Astronomical Society. Vanderburg's co-authors are lead author   
   Elyse Incha, at the University of Wisconsin at Madison, and amateur   
   astronomers Tom Jacobs and Daryll LaCourse, along with scientists at   
   NASA, the Center for Astrophysics of Harvard and the Smithsonian, and   
   the University of North Carolina at Chapel Hill.   
      
   Data squeeze In 2009, NASA launched the Kepler telescope into space,   
   where it followed the Earth's orbit and continuously monitored millions   
   of stars in a patch of the northern sky. Over four years, the telescope   
   recorded the brightness of over 150,000 stars, which astronomers used   
   to discover thousands of possible planets beyond our solar system.   
      
   Kepler kept observing beyond its original three-and-a-half-year mission,   
   until May 2013, when the second of four reaction wheels failed. The wheels   
   served as the spacecraft's gyroscopes, helping to keep the telescope   
   pointed at a particular point in the sky. Kepler's observations were   
   put on pause while scientists searched for a fix.   
      
   One year later, Kepler restarted as "K2," a reworked mission that used   
   the sun's wind to balance the unsteady spacecraftin a way that kept   
   the telescope relatively stable for a few months at a time -- a period   
   called a campaign. K2 went on for another four years, observing over   
   half a million more stars before the spacecraft finally ran out of fuel   
   during its 19th campaign. The data from this last campaign comprised   
   only a week of high-quality observations and another 10 days of noisier   
   measurements as the spacecraft rapidly lost fuel.   
      
   "We were curious to see whether we could get anything useful out of this   
   short dataset," Vanderburg says. "We tried to see what last information   
   we could squeeze out of it."  By eye Vanderburg and Incha presented the   
   challenge to the Visual Survey Group, a team of amateur and professional   
   astronomers who hunt for exoplanets in satellite data. They search by   
   eye through thousands of recorded light curves of each star, looking   
   for characteristic dips in brightness that signal a "transit," or the   
   possible crossing of a planet in front of its star.   
      
   The citizen scientists are especially suited to combing through short   
   datasets such as K2's very last campaign.   
      
   "They can distinguish transits from other wacky things like a glitch in   
   the instrument," Vanderburg says. "That's helpful especially when your   
   data quality begins to suffer, like it did in K2's last bit of data."   
   The astronomers spent a few days efficiently looking through the light   
   curves that Kepler recorded from about 33,000 stars. The team worked   
   with only a week's worth of high-quality data from the telescope before   
   it began to lose fuel and focus. Even in this short window of data,   
   the team was able to spot a single transit in three different stars.   
      
   Incha and Vanderburg then looked at the telescope's very last,   
   lower-quality observations, taken in its last 11 days of operation, to   
   see if they could spot any additional transits in the same three stars --   
   evidence that a planet was periodically circling its star.   
      
   During this 11-day period, as the spacecraft was losing fuel, its   
   thrusters fired more erratically, causing the telescope's view to   
   drift. In their analysis, the team focused on the region of each star's   
   light curves between thruster activity, to see if they could spot any   
   additional transits in these less data-noisy moments.   
      
   This search revealed a second transit for K2-416 b and K2-417 b,   
   validating that they each host a planet. The team also detected a similar   
   dip in brightness for K2-417 b in data taken of the same star by NASA's   
   Transiting Exoplanet Survey Satellite (TESS), a mission that is led and   
   operated by MIT.   
      
   Data from TESS helped to confirm the planet candidate around this star.   
      
   "Those two are pretty much, without a doubt, planets," Incha says. "We   
   also followed up with ground-based observations to rule out all kinds of   
   false positive scenarios for them, including background star interference,   
   and close- in stellar binaries."  "These are the last chronologically   
   observed planets by Kepler, but every bit of the telescope's data is   
   incredibly useful," Incha says. "We want to make sure none of that data   
   goes to waste, because there are still a lot of discoveries to be made."   
   This research was supported, in part, by MIT, NASA, and the University   
   of Wisconsin Undergraduate Academic Awards.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Astronomy # Extrasolar_Planets # Stars #   
                   Space_Exploration # Space_Telescopes # NASA # Pluto #   
                   Kuiper_Belt   
       * RELATED_TERMS   
             o Spitzer_space_telescope o Uranus'_natural_satellites   
             o Extrasolar_planet o Radio_telescope o   
             Compton_Gamma_Ray_Observatory o Uranus o Space_observatory   
             o Johannes_Kepler   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Massachusetts_Institute_of_Technology. Original written by Jennufer   
   Chu. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Elyse Incha, Andrew Vanderburg, Tom Jacobs, Daryll LaCourse, Allyson   
         Bieryla, Emily Pass, Steve B Howell, Perry Berlind, Michael Calkins,   
         Gilbert Esquerdo, David W Latham, Andrew W Mann. Kepler's last   
         planet discoveries: two new planets and one single-transit candidate   
         from K2 campaign 19. Monthly Notices of the Royal Astronomical   
         Society, 2023; 523 (1): 474 DOI: 10.1093/mnras/stad1049   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230530125403.htm   
      
   --- up 1 year, 13 weeks, 1 day, 10 hours, 50 minutes   
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)   
   SEEN-BY: 15/0 106/201 114/705 123/120 153/7715 218/700 226/30 227/114   
   SEEN-BY: 229/110 112 113 307 317 400 426 428 470 664 700 291/111 292/854   
   SEEN-BY: 298/25 305/3 317/3 320/219 396/45   
   PATH: 317/3 229/426