Melina's Physics 111 Blog: Gliese 667C and its Possibly Habitable Super-Earths

Gliese 667Cc is one of seven (one unconfirmed) exoplanets that orbit Gliese 667C, one of the three stars in the system Gliese 667 located in the constellation Scorpius. The triple-star system Gliese 667 is located about 22.1 light years (or 6.97 pc) away from earth. That makes its parallax 0.143”. See below:

Of the seven planets, three have been categorized as super-Earths. Super-earths are basically exoplanets that are larger in mass than earth, yet smaller in mass than our gas giants, Uranus and Neptune. These super-Earths also lie in what we call the “habitable zone,” the region where temperatures are cool enough for water to exist in its liquid form. It is also believed that these planets are rocky, like earth, and have low levels of heavy elements, which is rare.

Gliese 667C is a red dwarf and is much fainter than the sun. Its surface temperature is about 3700K. Its absolute magnitude is 11.03, while the sun’s is 4.83. Its radius is about 0.42 solar radii (or 2.92×10⁸ m). The distance from this star to its super-Earth, Gliese 667Cc, is only about 0.125 AU. That means that at the surface of this planet, Gliese 667C has an angular size of 1.79°. See below:

Gliese 667Cc has a radius of about 1.76 earth radii (or 1.12×10⁹ m). It is believed to be tidally locked to its parents star, meaning they continuously face each other in the same spot. This means it would have a hemisphere that is always bright and a hemisphere that is always dark. Meaning if I lived there, I could be a night owl throughout the day! Since it parent star is a part of a triple-star system, it is possible for all three stars to be visible in the daytime. Its orbital period is around 28 earth days (only one month). So technically, if life could exist on this planet, we could celebrate our birthday every month! Only down side to that is we’d all be very old, in Gliese 667Cc years. I’d be 264 years old!

The system Gliese 667 has a right ascension of 17h18m57s. Since we’re in February now, the right ascension at midnight is 10h, meaning our field of visibility would span between 4h-16h; thus, we would not be able to see this system tonight at midnight. However, next month, in March, the right ascension at midnight would be 12h, giving us a field of visibility between 6h-18h; thus, we would be able to see it at midnight next month. So mark your calendars!