MSGID: 1:317/3 645334f8   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Astronomers spot a star swallowing a planet    
    Earth will meet a similar fate in 5 billion years.    
      
     Date:   
         May 3, 2023   
     Source:   
         Massachusetts Institute of Technology   
     Summary:   
         Scientists have observed a star swallowing a planet for the   
         first time.   
      
         Earth will meet a similar fate in 5 billion years.   
      
      
         Facebook Twitter Pinterest LinkedIN Email   
      
   ==========================================================================   
   FULL STORY   
   ==========================================================================   
   As a star runs out of fuel, it will billow out to a million times   
   its original size, engulfing any matter -- and planets -- in its   
   wake. Scientists have observed hints of stars just before, and shortly   
   after, the act of consuming entire planets, but they have never caught   
   one in the act until now.   
      
   In a study that will appear in Nature, scientists at MIT, Harvard   
   University, Caltech, and elsewhere report that they have observed a star   
   swallowing a planet, for the first time.   
      
   The planetary demise appears to have taken place in our own galaxy, some   
   12,000 light-years away, near the eagle-like constellation Aquila. There,   
   astronomers spotted an outburst from a star that became more than 100   
   times brighter over just 10 days, before quickly fading away. Curiously,   
   this white-hot flash was followed by a colder, longer-lasting signal. This   
   combination, the scientists deduced, could only have been produced by   
   one event: a star engulfing a nearby planet.   
      
   "We were seeing the end-stage of the swallowing," says lead author   
   Kishalay De, a postdoc in MIT's Kavli Institute for Astrophysics and   
   Space Research.   
      
   What of the planet that perished? The scientists estimate that it was   
   likely a hot, Jupiter-sized world that spiraled close, then was pulled   
   into the dying star's atmosphere, and, finally, into its core.   
      
   A similar fate will befall the Earth, though not for another 5 billion   
   years, when the sun is expected to burn out, and burn up the solar   
   system's inner planets.   
      
   "We are seeing the future of the Earth," De says. "If some other   
   civilization was observing us from 10,000 light-years away while the sun   
   was engulfing the Earth, they would see the sun suddenly brighten as it   
   ejects some material, then form dust around it, before settling back to   
   what it was."  The study's MIT co-authors include Deepto Chakrabarty,   
   Anna-Christina Eilers, Erin Kara, Robert Simcoe, Richard Teague, and   
   Andrew Vanderburg, along with colleagues from Caltech, the Harvard and   
   Smithsonian Center for Astrophysics, and multiple other institutions.   
      
   Hot and cold The team discovered the outburst in May 2020. But it took   
   another year for the astronomers to piece together an explanation for   
   what the outburst could be.   
      
   The initial signal showed up in a search of data taken by the Zwicky   
   Transient Facility (ZTF), run at Caltech's Palomar Observatory in   
   California. The ZTF is a survey that scans the sky for stars that   
   rapidly change in brightness, the pattern of which could be signatures   
   of supernovae, gamma-ray bursts, and other stellar phenomena.   
      
   De was looking through ZTF data for signs of eruptions in stellar binaries   
   - - systems in which two stars orbit each other, with one pulling mass   
   from the other every so often and brightening briefly as a result.   
      
   "One night, I noticed a star that brightened by a factor of 100 over   
   the course of a week, out of nowhere," De recalls. "It was unlike any   
   stellar outburst I had seen in my life."  Hoping to nail down the source   
   with more data, De looked to observations of the same star taken by   
   the Keck Observatory in Hawaii. The Keck telescopes take spectroscopic   
   measurements of starlight, which scientists can use to discern a star's   
   chemical composition.   
      
   But what De found further befuddled him. While most binaries give off   
   stellar material such as hydrogen and helium as one star erodes the other,   
   the new source gave off neither. Instead, what De saw were signs of   
   "peculiar molecules" that can only exist at very cold temperatures.   
      
   "These molecules are only seen in stars that are very cold," De says. "And   
   when a star brightens, it usually becomes hotter. So, low temperatures and   
   brightening stars do not go together."  "A happy coincidence" It was then   
   clear that the signal was not of a stellar binary. De decided to wait   
   for more answers to emerge. About a year after his initial discovery,   
   he and his colleagues analyzed observations of the same star, this   
   time taken with an infrared camera at the Palomar Observatory. Within   
   the infrared band, astronomers can see signals of colder material, in   
   contrast to the white-hot, optical emissions that arise from binaries   
   and other extreme stellar events.   
      
   "That infrared data made me fall off my chair," De says. "The source   
   was insanely bright in the near-infrared."  It seemed that, after its   
   initial hot flash, the star continued to throw out colder energy over   
   the next year. That frigid material was likely gas from the star that   
   shot into space and condensed into dust, cold enough to be detected at   
   infrared wavelengths. This data suggested that the star could be merging   
   with another star rather than brightening as a result of a supernovae   
   explosion.   
      
   But when the team further analyzed the data and paired it with   
   measurements taken by NASA's infrared space telescope, NEOWISE, they   
   came to a much more exciting realization. From the compiled data,   
   they estimated the total amount of energy released by the star since   
   its initial outburst, and found it to be surprisingly small -- about   
   1/1,000 the magnitude of any stellar merger observed in the past.   
      
   "That means that whatever merged with the star has to be 1,000 times   
   smaller than any other star we've seen," De says. "And it's a happy   
   coincidence that the mass of Jupiter is about 1/1,000 the mass of the   
   sun. That's when we realized: This was a planet, crashing into its star."   
   With the pieces in place, the scientists were finally able to explain   
   the initial outburst. The bright, hot flash was likely the final moments   
   of a Jupiter-sized planet being pulled into a dying star's ballooning   
   atmosphere. As the planet fell into the star's core, the outer layers   
   of the star blasted away, settling out as cold dust over the next year.   
      
   "For decades, we've been able to see the before and after," De   
   says. "Before, when the planets are still orbiting very close to their   
   star, and after, when a planet has already been engulfed, and the star   
   is giant. What we were missing was catching the star in the act, where   
   you have a planet undergoing this fate in real-time. That's what makes   
   this discovery really exciting."  This research was supported, in part,   
   by NASA, the U.S. National Science Foundation, and the Heising-Simons   
   Foundation.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Stars # Extrasolar_Planets # Astronomy # Black_Holes   
             o Earth_&_Climate   
                   # Geomagnetic_Storms # Energy_and_the_Environment #   
                   Floods # Earth_Science   
       * RELATED_TERMS   
             o Venus o Red_giant o Stellar_evolution o Extrasolar_planet o   
             Geologic_temperature_record o Structure_of_the_Earth o Neptune   
             o History_of_Earth   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Massachusetts_Institute_of_Technology. Original written by Jennifer   
   Chu. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Related Multimedia:   
       *   
       An_artist's_impression_shows_a_doomed_planet_skimming_the_surface_of_its   
         star.   
      
   ==========================================================================   
   Journal Reference:   
      1. Kishalay De, Morgan MacLeod, Viraj Karambelkar, Jacob E. Jencson,   
      Deepto   
         Chakrabarty, Charlie Conroy, Richard Dekany, Anna-Christina   
         Eilers, Matthew J. Graham, Lynne A. Hillenbrand, Erin Kara, Mansi   
         M. Kasliwal, S.   
      
         R. Kulkarni, Ryan M. Lau, Abraham Loeb, Frank Masci, Michael   
         S. Medford, Aaron M. Meisner, Nimesh Patel, Luis Henry   
         Quiroga-Nun~ez, Reed L.   
      
         Riddle, Ben Rusholme, Robert Simcoe, Lora'nt O. Sjouwerman,   
         Richard Teague, Andrew Vanderburg. An infrared transient from   
         a star engulfing a planet. Nature, 2023; 617 (7959): 55 DOI:   
         10.1038/s41586-023-05842-x   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230503121315.htm   
      
   --- up 1 year, 9 weeks, 2 days, 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: 229/110 112 113 307 317 400 426 428 470 664 700 292/854 298/25   
   SEEN-BY: 305/3 317/3 320/219 396/45   
   PATH: 317/3 229/426