A Close Look at Proxima Centauri

by | Feb 14, 2006 | Exoplanetary Science

Greg Laughlin’s systemic site, indispensable for those studying exoplanet detections, now offers a close look at Proxima Centauri, at 4.22 light years the closest known star to the Sun. Intriguing facts include these:

  • While holding about 11 percent of the Sun’s mass, Proxima has an average density several times that of lead (the Sun’s average density is about 1.4 times that of water)
  • Proxima’s total luminosity is a thousand times less than the Sun’s
  • Because radiation alone cannot get Proxima’s fusion energy from its interior to the surface, the star relies on convection — the motion of stellar gases physically takes energy away from the core (by contrast, the Sun has a radiative core)

    • All of which has powerful consequences, especially in terms of longevity — Proxima Centauri will still be shining two trillion years from now. You’ll want to read the entire post, which goes into the details of a paper Laughlin wrote (with Peter Bodenheimer and Fred Adams) that examines the fate of red dwarfs like Proxima. It also offers a close look at what a terrestrial planet orbiting a red dwarf might be like. And it reports on the work of UCSC graduate student Ryan Montgomery, who is carrying out computer work to simulate the accretion of terrestrial-mass planets from small planetesimals in this environment.

    As for detecting such worlds, check this statement about using the transit method:

    In principle, a 1% photometric dip is readily detectable, and in fact, amateur astronomers who participate in the transitsearch.org collaboration routinely achieve detection thresholds of considerably better than 1%… Skilled amateurs such as [Ron] Bissinger or Tony Vanmunster have backyard techniques that are good enough to detect the passage of even a Mars-sized body in front of an 11th magnitude 0.1 solar mass red dwarf. Wow.

    Wow indeed. Laughlin lays out a list of candidate stars for potential transit detections and promises followups on Montgomery’s simulations. Oh, and the paper mentioned above is Laughlin, Bodenheimer and Adams, “The End of the Main Sequence,” in The Astrophysical Journal 482 (1997), pp. 420-434, abstract available here.

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    In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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