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41430 Arietis Quadruple Star System

  1. Mar 6, 2015 #1
    I read an article (Planet 'Reared' by Four Parent Stars) the other day and came across the statement: "Astronomers think it's highly unlikely that this planet, or any moons that might circle it, could sustain life." I began to wonder why, but there was no further explanation in the article.

    So I began to learn more about the system, beginning with the original papers (see below). I was able to get all the information I needed for 30 Ari A & B, but only the approximate mass (~0.5 M☉) of 30 Ari C, which is suppose to be the newly discovered red dwarf star 24 AU from 30 Ari B. I was not able to find any information on 30 Ari A's stellar companion, not even its name or catalog number. If anyone can help me locate information on what should be 30 Ari D [?], I would be very grateful.

    With regard to whether 30 Ari Bb could sustain life, according to Kopparapu et al. (2014) (see below), the 'conservative habitable zone' for 30 Ari B should be between 1.28 and 2.23 AU. Since the exoplanet 30 Ari Bb is 0.995 AU from its star, it would appear to be too close to its star to support liquid water on the surface of any of its moons.

    However, Kopparapu et al. (2014) does not factor in albedo. An Earth-like moon with an albedo of 32.5%, and a semi-major axis of 5 million km from 30 Ari Bb would have an orbit of 23.2 days, with mean surface temperatures ranging from 28.7°C to 11.1°C with each orbit. The temperatures were calculated using the Stefan-Boltzmann law and factoring in for albedo, but does not include radiative forcing or allowances for atmospheric pressure.

    A temperature shift of 17.6°C every 11.6 days seems rather extreme. I am not sure how life would evolve in such an environment, but it is still capable of supporting liquid water on its surface. An Earth-like moon with a semi-major axis of 5 million km from 30 Ari Bb should also not be tidally locked.

    Jupiter has 67 confirmed moons. Certainly an exoplanet with 10 Jupiter masses must also have a large number of moons. Granted the 30 Ari B solar system is only 910 million years old, so it is unlikely that there is any kind of life on any of those moons currently. But I still see no reason why life could not eventually evolve, as long as liquid surface water is present.

    If anyone can point out what I am missing, it would be appreciated.

    Know the Star, Know the Planet. III. Discovery of Late-Type Companions to Two Exoplanet Host Stars - arXiv : 1503.01211v1 [PDF]
    A substellar component orbiting the F-star 30 Ari B - arXiv : 0912.4619v1 [PDF]
    Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass - arXiv : 1404.5292v2 [PDF]
  2. jcsd
  3. Mar 6, 2015 #2


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    Are you sure about that?
  4. Mar 6, 2015 #3
    Pretty sure
    [emphasis added]

    They certainly make numerous references to albedo, but there model does not appear to include it.
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