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Extrasolar planets

TESS Discovers Two New Jupiter-Sized Exoplanets Orbiting M-Dwarf Stars

Strategic Insights

— 1 min read

Astronomers from the University of California, Irvine, and their international collaborators have made a groundbreaking discovery using NASA's Transiting Exoplanet Survey Satellite (TESS). The team has uncovered two new exoplanets, orbiting M-dwarf stars, that are similar in size to Jupiter and possess Saturn-like densities. These findings were published in a research paper on the arXiv pre-print server on October 13, 2023.

Key Takeaways:

  • The two exoplanets, TOI-5916 b and TOI-6158 b, were discovered using TESS's ongoing survey of the brightest stars near the sun.
  • Both planets have a size similar to that of Jupiter and possess Saturn-like densities, with TOI-5916 b having a density of 0.73 g/cm3 and TOI-6158 b having a density of 0.66 g/cm3.
  • The planets orbit their host stars every 2.37 days (TOI-5916 b) and 3.04 days (TOI-6158 b), respectively.
  • The distances between the planets and their host stars are approximately 0.028 AU (TOI-5916 b) and 0.033 AU (TOI-6158 b).
  • The equilibrium temperatures of the planets are estimated to be 716 K (TOI-5916 b) and 636 K (TOI-6158 b).
  • The study confirms the planetary nature of the transit signals in the light curves of the two M-dwarf stars using ground-based photometry and radial velocity data.
  • The newly detected planets join the relatively short list of 32 known GEMS (giant exoplanets around M-dwarfs) and the more common population of warm Jupiters.
  • In addition to the two exoplanets, the parent stars, TOI-5916 and TOI-6158, are approximately two times smaller and less massive than the sun.

Statistics:

  • 200,000 brightest stars near the sun being surveyed by TESS
  • 7,700 candidate exoplanets (TESS Objects of Interest, or TOI) identified since its launch in 2018
  • 705 confirmed exoplanets out of the 7,700 candidates
  • Distance of TOI-5916 from the observer: 639 light years
  • Effective temperature of TOI-5916: 3,541 K
  • Effective temperature of TOI-6158: 3,467 K
  • Distance of TOI-6158 from the observer: 592 light years

Sources:

  • arXiv (2025). DOI: 10.48550/arxiv.2510.11798
  • Shane O'Brien et al, Searching for GEMS: TOI-5916 b & TOI-6158 b are two Saturn-density planets orbiting M2 dwarfs, arXiv (2025). DOI: 10.48550/arxiv.2510.11798
  • TESS detects two new Jupiter-sized exoplanets orbiting dwarf stars (2025, October 21)
  • Phys.org
  • Journal information: arXiv

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