Hubble discovers water-rich exoplanet with steamy atmosphereas the pursuit of discovering life beyond Earth is intricately tied to our exploration of water throughout the cosmos and on other celestial bodies. Water, one of the most prevalent molecules in the universe, plays a fundamental role in all recognized life forms, acting as a crucial solvent necessary for essential biological processes. This recognition fuels astronomers' enthusiasm whenever they observe indications of water vapor on distant exoplanets.
An intriguing find in the realm of exoplanet exploration is GJ 9827d. This planet, no larger than twice the size of Earth, presents the possibility of harboring a water-rich atmosphere. Despite its small size, GJ 9827d is a far cry from being hospitable, with scorching temperatures reaching up to 800 degrees Fahrenheit, reminiscent of Venus. Instead of being a potential haven for life, it's a world enveloped in steam.
A recent breakthrough by NASA's Hubble Space Telescope marks a significant leap forward in exoplanetary studies. The telescope has detected water vapor in the atmosphere of GJ 9827d, making it the smallest exoplanet where such a detection has been made. This discovery brings us closer to pinpointing planets with environments more reminiscent of Earth.
"This would be the first time that we can directly show through an atmospheric detection, that these planets with water-rich atmospheres can actually exist around other stars," said team member Björn Benneke of the Trottier Institute for Research on Exoplanetsat Université de Montréal. "This is an important step toward determining the prevalence and diversity of atmospheres on rocky planets."
“„Water on a planet this small is a landmark discovery. It pushes closer than ever to characterizing truly Earth-like worlds.- Laura Kreidberg
Under the leadership of Ian Crossfield from Kansas University, the Hubble observations were directed not only toward identifying atmospheric molecules but specifically toward the hunt for water vapor. Whether the identified water vapor constitutes a predominant element or a minor constituent within a hydrogen-rich atmosphere, this discovery holds profound significance.
"Until now, we had not been able to directly detect the atmosphere of such a small planet. And we're slowly getting in this regime now," added Benneke.
"At some point, as we study smaller planets, there must be a transition where there's no more hydrogen on these small worlds, and they have atmospheres more like Venus (which is dominated by carbon dioxide)."
Two primary theories arise concerning the atmosphere of GJ 9827d. It might resemble a larger version of Jupiter's moon Europa, known for its extensive water reservoirs beneath its icy crust, or it might resemble a mini-Neptune with a hydrogen-rich atmosphere and pockets of water.
“„The planet GJ 9827d could be half water, half rock. And there would be a lot of water vapor on top of some smaller rocky body.- Björn Benneke
If the planet indeed possesses a water-rich atmosphere, it probably originated farther from its star, where ice was plentiful, before migrating to its current, warmer orbit. Alternatively, it might have initially formed near its hot star, resulting in only minimal traces of water in its atmosphere.
An illustration of the water-rich exoplanet close to the sun The Hubble study entailed monitoring the planet through 11 transits spanning three years. During these transits, when the planet crossed in front of its star, Hubble captured the spectral signature of water molecules in the atmosphere.
An important aspect is that any clouds present on the planet are situated at a low enough altitude to avoid obstructing Hubble's view, facilitating the detection of water vapor above them.
"Observing water is a gateway to finding other things," said Thomas Greene, an astrophysicist at NASA’s Ames Research Centerin California’s Silicon Valley. "This Hubble discovery opens the door to future study of these types of planets by the James Webb Space Telescope. JWST can see much more with additional infrared observations, including carbon-bearing molecules like carbon monoxide, carbon dioxide, and methane. Once we get a total inventory of a planet’s elements, we can compare those to the star it orbits and understand how it was formed," Greene concluded. Discovered originally by NASA's Kepler Space Telescope in 2017, GJ 9827d orbits a red dwarf star, GJ 9827, situated 97 light-years away in the constellation Pisces, completing a full orbit every 6.2 days.
Although this distant world isn't conducive to life as we know it, it offers invaluable insights into the vast diversity and characteristics of exoplanetary atmospheres, advancing our comprehension of the universe's intricacies.
In essence, NASA Hubble's groundbreaking detection of water vapor on exoplanet GJ 9827d represents a monumental leap forward in our cosmic understanding.
Despite its extreme and steamy conditions, rendering it unsuitable for life as we understand it, this discovery heralds a new era in the examination of exoplanetary atmospheres, particularly those resembling Earth's. It challenges existing paradigms and broadens our understanding of the potential habitats where water-rich planets may thrive.
As our exploration of these distant realms persists, each revelation, such as GJ 9827d, propels us closer to unraveling the timeless question of our place in the universe and enriches our insight into the myriad planetary systems that populate the cosmos.