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A Gas Giant in the Habitable Zone

HD 73526 is a G6 star (i.e., a solar-like main sequence dwarf) that has just made some interesting news. As Greg Laughlin writes in a new posting on his Systemic site, Paul Butler, Geoff Marcy, Chris Tinney and collaborators with the Anglo-Australian Planet Search Project have found that the planetary system around the star displays an unusual resonance whose motion over time can be viewed in this online mpeg file. But even more striking is the nature of the two gas giant planets found here. The inner (HD 73526b) orbits with a 188 day period, while the outer has a period of 379 days. Let Laughlin tell it:

Planet c is a true room temperature gas giant. Liquid water likely blows in gusty sheets across its cloudy skies. (And it’s worth noting that any large moons circling HD 73526 c lie pleasantly within the stellar habitable zone.)

Got that? Centauri Dreams yields to no one when it comes to fascination over exoplanetary orbits, particularly unusual resonances between distant worlds, but Laughlin is talking about moons that, if they exist, are clearly in the habitable zone of this star. Of course, we don’t know whether, planet c has moons or not, but it is some comfort to realize just how many satellites we’ve found around the gas giants in our own system. And the vision of life coming into existence and evolving in such a setting remains breathtaking, even in a time when exoplanetary discoveries are coming in almost too fast to catalog.

The paper, accepted by the Astrophysical Journal, is Tinney, Butler, Marcy et al., “The 2:1 resonant exoplanetary system orbiting HD73526,” with an abstract now available.

Comments on this entry are closed.

  • Joseph March 1, 2006, 22:23

    Hmm about 345 ly distance, this star is listed as somewhat metal-rich. Has there been any scenarios created for a planet such as HD 73526b? What would the radiation belts be in comparison to a cold gas giant like Jupiter?

  • Administrator March 2, 2006, 9:02

    At this point, I suspect we could only conjecture about radiation belts around such a world, though I’ll pass this along to Greg Laughlin to see if anyone in the Anglo-Australian group has worked up more details.

  • Joseph March 2, 2006, 14:59

    Just curious if any habitable zone parameters had ever been worked out for such a situation. The article itself is very heartening but started me to thinking when I tried to visualise an earth sized moon circling planet c. Of course very close in gravitational forces would probably make for some lively geological activity. The radiation zone around a planet such as c would be the biggest variable for life.

    Great to think about though. How would a civilization develope in such a situation?

  • Administrator March 2, 2006, 17:09

    Imagine, too (given what we see around Jupiter and Saturn) having four or five water worlds orbiting a single Jupiter-class planet in the habitable zone. How emerging life on such worlds might spread and affect the entire system is fascinating to contemplate.