VILLANOVA, Pa. – Two Villanova University astronomers are part of an international team that has been studying the potential habitability of Proxima b, a newly discovered “Earth-size” planet orbiting in the liquid water habitable zone of the red dwarf star—Proxima Centauri. Proxima Centauri is the nearest star to the Sun, about 4.25 light years away. The announcement of the discovery of the exoplanet, the closest in proximity to the Earth to date, was made on August 24 by the European Southern Observatory (ESO). The major finding by Guillem Anglada-Escude’ from Queen Mary University of London, who led an international team of astronomers, opens up the exciting possibility that a planet capable of supporting life may be our celestial next door neighbor.
The initial findings of Edward F. Guinan, PhD, Villanova Professor of Astrophysics & Planetary Science, Scott G. Engle, PhD, Research Assistant Professor of Astrophysics & Planetary Science at Villanova, and their European colleagues’ study shows that although the present data indicate a wide range of possibilities, the planet could have water and possibly oceans that could make it habitable and suitable for life. The presence of liquid water on an exoplanet is considered an important (but not exclusionary) requisite to be habitable.
“Depending on how much the host star’s early strong magnetic-induced X-ray, Ultraviolet and plasma fluxes affected the planet and its original water content, the planet now could be like Mars (dry, cold and thin—or no—atmosphere); Venus (hot, thick carbon dioxide, no water, not viable to support life); or an ocean planet like the Earth. These possibilities have not been ruled in or ruled out,” said Guinan. “It’s an open question until additional observations are made to distinguish among these outcomes.”
The discovery of the new exoplanet so close to Earth and thus accessible for further follow-up studies represents a major breakthrough in astronomy and astrophysics, according to Guinan. Because of the closeness of the planet to us, future instruments such as the James Webb Space Telescope (JWST), the Wide Field Infrared Space Telescope (WFIRST), and huge sophisticated ground-based telescopes like the Thirty Meter Telescope (TMT) and the even bigger 39-meter European-Extremely Large Telescopes (E-ELT) may be able to image Proxima b and discerning surface features. This could aid in securing spectroscopy to determine the chemical composition of its atmosphere to see if water is present.
Another appealing future option to study Proxima b (as well as other nearby exoplanets) is the New Worlds Mission (NWM) being discussed by NASA to deploy a large Star shade in space to block the star’s light. This would permit the planet to be seen through another space telescope without the interfering glare of the host star. Spectroscopy returned from NWM could determine the presence (or absence) of water vapor as well searching for the telltale spectroscopic signatures of life –called bio-signatures that include oxygen, ozone, and methane.
“The discovery of Proxima b represents a thrilling new milestone in space exploration,” added Guinan. “It is an honor for Scott (Engle) and I to be participants in the ongoing research into the habitability of the planet and the possibilities it opens up for mankind.”
The paper –“The Habitability of Proxima b” was submitted to The Journal of Astronomy & Astrophysics and posted to ArXiv.org on August 24, 2016. The links to the paper and description of the results are found on the project’s newly established website at:www.proximacentauri.info
The initial finding of this paper concludes that “Proxima b is a viable candidate habitable planet.” The group will continue its research to confirm habitability of the exoplanet.
“Astronomers have been trying (and hoping) to find planets in the alpha Cen system for years now. To find one around proxima Cen, the closest of the sun’s stellar neighbors, and to then find it orbits within the star's classical habitable zone, is a pretty big deal, to say the least,” Engle said. “It’s great to be involved in studying the planet’s potential habitability. Astronomers all over the world will be intensely studying this planet for many more years to come.”
The US investigators gratefully acknowledge support by the NSF and NASA through grants NSF/RUI-1009903, HST-GO-13020.001-A and Chandra Award GO2-13020X to Villanova University.