Earth Sky | 2 are likely Earth-like worlds, only 16 light-years away

View larger. | Nearby habitable planets? Astronomers have discovered two new Earth-mass exoplanets orbiting the habitable zone of a nearby red dwarf star. The star is less than 16 light-years away. This artist’s concept shows Kepler-186f, the first Earth-sized planet discovered orbiting the habitable zone of another star, about 558 light-years away. Image via NASA/SETI Institute.

Astronomers have discovered an increasing number of rocky exoplanets, worlds comparable in size to Earth. This month (December 15, 2022), an international team of astronomers says it has discovered two more worlds in our galactic neighborhood. These worlds are less than 16 light-years away, so close, relatively speaking! And they’re in their star’s habitable zone, the region where liquid water could exist.

For comparison, Proxima Centauri b is the closest Earth-mass exoplanet, 4.2 light-years away. It is also similar in size to Earth and in the habitable zone to its star.

Researchers at the Institute of Astrophysics in the Canary Islands led the team that made the discovery. A new peer-reviewed paper has been accepted for publication by the journal Astronomy and astrophysics.

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2 Earth-like worlds

The two new planets – GJ 1002b and GJ 1002c – orbit the red dwarf star GJ 1002, less than 16 light-years from Earth. This is very close in terms of stellar distances. Both planets have similar masses to Earth and orbit within the star’s habitable zone. This is the region around the star where temperatures can allow liquid water to exist on rocky planets. The discovery adds to previous findings showing that rocky worlds close in size and mass to Earth are very common in our galaxy. Lead author Alejandro Suárez Mascareño at the Astrophysical Institute of the Canary Islands stated:

Nature seems intent on showing that Earth-like planets are very common. With these two, we now know of seven in planetary systems very close to the Sun.

GJ 1002b takes 10 days to orbit its star, while GJ 1002c takes just over 21 days.

The astronomers used telescopic instruments ESPRESSO (Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) and CARMENES (Calar Alto High-Resolution search for M dwarfs with Exoearts with Near-infrared and Échelle Spectrographs) to make their detailed observations.

habitable? Yeah. haunted? we do not know

The star GJ 1002 is a red dwarf, smaller and cooler than our Sun. This may not sound great for the prospects for habitability on any planets. But red dwarfs have their own habitable zones, just as sun-like stars do. These are the areas where liquid water can exist on the planet’s surface.

The habitable zone of a red dwarf star is located closer to the star than the habitable zone of our Sun. Co-author Vera Maria Passegger said:

GJ 1002 is a red dwarf star, barely one-third the mass of the Sun. It’s a cool, dim star. This means that its habitation zone is very close to the star.

Since both of these newly discovered planets orbit within this habitable zone, they likely have conditions suitable for life. But do they have a life? There’s no guarantee of that, and the answer is we don’t know. Scientists warn that “habitability” depends on multiple factors, in addition to temperature.

But planets within habitable zones are certainly the best places to start looking for evidence of life “as we know it.” So the next step might be to study these worlds with the giant Webb space telescope, looking for clues as to whether life might exist on them.

atmospheric analysis

This is the good news. Because the two planets are so close, scientists can study their atmospheres. Co-author Junay González-Hernandez noted that Webb is not the only telescope that can be used to study the atmospheres of distant worlds:

The future ANDES spectrograph of ESO’s ELT telescope with which IAC is involved can study the presence of oxygen in GJ 1002c’s atmosphere.

Astronomers can analyze the atmosphere based on reflected light or thermal emission. In most cases, planets need to transit in front of their stars for this type of analysis to take place. But there are other ways, too, the paper says:

Characterization of exoplanet atmospheres is usually done by transmission spectroscopy, which requires planetary transits. However, this is not the only possibility for studying exoplanet atmospheres. In recent years, it has been suggested that coupling high-resolution spectrometers with high-angular resolution imaging could open an alternative pathway for studying the atmospheres of planets in the solar neighborhood (Lovis et al. 2017).

GJ 1002 is one of the few known nearby systems with planets that could host habitable environments. The proximity of the host star to the Sun makes the angular sizes of the orbits of both planets large enough to study their atmospheres via high-resolution, high-contrast spectroscopy using instruments such as the ELT’s ANDES receiver spectrometer or the LIFE mission.

Large instrument in the lab with connecting tones and wires.
This is the ESPRESSO (Echelle Spectrograph for Rocky Exoplanet and Stable Spectroscopic Observations) instrument used by ESO’s Very Large Telescope (VLT). Image via ESO.

team effort

Getting the new results in was really a team effort. ESPRESSO and CARMENES were vital to the ability to observe GJ 1002b and GJ 1002c. Mascarino said:

Either group would have had many difficulties if they had tackled this work independently. Together, we have made far greater progress than we would have done independently.

In the future, the LIFE (Large Interferometer to Exoplanets) mission should also be able to study these planets more closely. Live is currently in the first study phase.

Bottom line: An international team of astronomers has discovered two of the closest Earth-like worlds yet, less than 16 light-years from Earth.

Source: Two moderate Earth-mass planets orbit the nearby star GJ 1002

Via The Astrophysical Institute of the Canary Islands

#Earth #Sky #Earthlike #worlds #lightyears

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