2023-05-03 カリフォルニア工科大学(Caltech)
◆この星は、12,000光年先の銀河系にあり、観測にはカリフォルニア工科大学のZwicky Transient Facility (ZTF)などを使用。今回の発見で、地球や他の惑星が、その内側にある恒星に飲み込まれる様子が分かった。
◆宇宙でこのような現象を直接観測したのは今回が初めてである。
＜関連情報＞
- https://www.caltech.edu/about/news/star-eats-planet-brightens-dramatically
- https://www.nature.com/articles/s41586-023-05842-x
惑星を飲み込む恒星からの赤外線遷移現象 An infrared transient from a star engulfing a planet
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-Nuñez,Reed L. Riddle,Ben Rusholme,Robert Simcoe,Loránt O. Sjouwerman,Richard Teague & Andrew Vanderburg
Nature Published:03 May 2023
DOI:https://doi.org/10.1038/s41586-023-05842-x
Abstract
Planets with short orbital periods (roughly under 10 days) are common around stars like the Sun1,2. Stars expand as they evolve and thus we expect their close planetary companions to be engulfed, possibly powering luminous mass ejections from the host star3,4,5. However, this phase has never been directly observed. Here we report observations of ZTF SLRN-2020, a short-lived optical outburst in the Galactic disk accompanied by bright and long-lived infrared emission. The resulting light curve and spectra share striking similarities with those of red novae6,7—a class of eruptions now confirmed8 to arise from mergers of binary stars. Its exceptionally low optical luminosity (approximately 1035 erg s−1) and radiated energy (approximately 6.5 × 1041 erg) point to the engulfment of a planet of fewer than roughly ten Jupiter masses by its Sun-like host star. We estimate the Galactic rate of such subluminous red novae to be roughly between 0.1 and several per year. Future Galactic plane surveys should routinely identify these, showing the demographics of planetary engulfment and the ultimate fate of planets in the inner Solar System.
