[BRIEF NOTE] On the possible detection of Proxima Centauri b

[rfmcdonald]

Space artist David A. Hardy shared the above 1972 painting, of a rocky world with pools of liquid on its surface in close orbit of Proxima Centauri, soon after the news broke of the possible discovery of a broadly Earth-like planet in orbit of the star nearest to our solar system. Matt Williams' Universe Today article "Earth-like Planet Around Proxima Centauri Discovered" has been frequently cited.

[T]he German weekly Der Spiegel announced recently that astronomers have discovered an Earth-like planet orbiting Proxima Centauri, just 4.25 light-years away. Yes, in what is an apparent trifecta, this newly-discovered exoplanet is Earth-like, orbits within it’s sun’s habitable zone, and is within our reach. But is this too good to be true? [. . . ] Citing anonymous sources, the magazine stated:

“The still nameless planet is believed to be Earth-like and orbits at a distance to Proxima Centauri that could allow it to have liquid water on its surface — an important requirement for the emergence of life. Never before have scientists discovered a second Earth that is so close by.”

In addition, they claim that the discovery was made by the European Southern Observatory (ESO) using the La Silla Observatory‘s reflecting telescope. Coincidentally, it was this same observatory that announced the discovery of Alpha Centauri Bb back in 2012, which was also declared to be “the closest exoplanet to Earth”. Unfortunately, subsequent analysis cast doubt on its existence, claiming it was a spurious artifact of the data analysis.

However, according to Der Spiegel’s unnamed source – whom they claim was involved with the La Silla team that made the find – this latest discovery is the real deal, and was the result of intensive work. “Finding small celestial bodies is a lot of hard work,” the source was quoted as saying. “We were moving at the technically feasible limit of measurement.”

The article goes on to state that the European Southern Observatory (ESO) will be announcing the finding at the end of August. But according to numerous sources, in response to a request for comment by AFP, ESO spokesman Richard Hook refused to confirm or deny the discovery of an exoplanet around Proxima Centauri. “We are not making any comment,” he is reported as saying.

The Pale Red Dot research project, devoted to the surveillance of Proxima Centauri in the search of detecting a close-orbiting planet, has reported on finding a possible signal.



A 2013 study did suggest a 10-20 day cycle of some sort. Such, the project acknowledges, may not be spoor of a planet at all but rather a function of the star or even the instruments used. Any planet more massive than one or two Earths would already have been detected, based on previous surveys.

If everything is as reported--if!--then there could well be a planet of mass comparable to that of the Earth orbiting the nearest star to our solar system within said star's circumstellar habitable zone. That by itself would not ensure that such a planet would be like Earth, as serious constraints to the habitability of exoplanets in red dwarf systems exist. In particular, Proxima Centauri's nature as a violent flare star means that even if a hypothetical planet did start off with the resources needed to support life, successive flares may have eroded the planet's surface into lifeless rock.

Even so, it goes without saying that the discovery of such a world would be epoch-making. Besides the potential of this world as itself, it signals remarkable things about the wider universe. If such an uncomprisingly dim and violent star as Proxima Centauri can support even a very broadly Earth-like planet, surely planets like ours must be quite common? How likely would it be that we are not alone?

D-Brief and The Dragon's Gaze have more. Suffice it to say I will be waiting for bated breath for more.