Category: habitable planet

Earth-Like Planet Discovered in Habitable Zone of Nearby Red Dwarf

M-type stars, also known as “red dwarfs,” have become a popular target for exoplanet hunters of late. This is understandable given the sheer number of terrestrial (i.e. rocky) planets that have been discovered orbiting around red dwarf stars in recent years. These discoveries include the closest exoplanet to our Solar System (Proxima b) and the seven planets discovered around TRAPPIST-1, three of which orbit within the star’s habitable zone.

The latest find comes from a team of international astronomers who discovered a planet around GJ 625, a red dwarf star located just 21 light years away from Earth. This terrestrial planet is roughly 2.82 times the mass of Earth (aka. a “super-Earth”) and orbits within the star’s habitable zone. Once again, news of this discovery is prompting questions about whether or not this world could indeed be habitable (and also inhabited).

The international team was led by Alejandro Mascareño of the Canary Islands Institute of Astrophysics (IAC), and includes members from the University of La Laguna and the University of Geneva. Their research was also supported by the Spanish National Research Council (CSIS), the Institute of Space Studies of Catalonia (IEEC), and the National Institute For Astrophysics (INAF).

Diagram showing GJ 625’s habitable zone in comparison’s to the Sun’s. Image Credit: IAC

The study which details their findings was recently accepted for publication by the journal Astronomy & Astrophysics, and appears online under the title “A super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625.” According to the study, the team used radial-velocity measurements of GJ 625 in order to determine the presence of a planet that has between two and three times the mass of Earth.

This discovery was part of the HARPS-N Red Dwarf Exoplanets Survey (HADES), which studies red dwarf stars to determine the presence of potentially habitable planets orbiting them. This survey relies on the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) instrument — which is part of the 3.6-meter Galileo National Telescope (TNG) at the IAC’s Roque de Los Muchachos Observatory on the island of La Palma.

Using this instrument, the team collected high-resolution spectroscopic data of the GJ 625 system over the course of three years. Specifically, they measured small variations in the star’s radial velocity, which are attributed to the gravitational pull of a planet. From a total of 151 spectra obtained, they were able to determine that the planet (GJ 625 b) was likely terrestrial and had a minimum mass of 2.82 ± 0.51 Earth masses.

Moreover, they obtained distance estimates that placed it roughly 0.078 AU from its star, and an orbital period estimate of 14.628 ± 0.013 days. At this distance, the planet’s orbit places it just within GJ 625’s habitable zone. Of course, this does not mean conclusively that the planet has conditions conducive to life on its surface, but it is an encouraging indication.

The Observatorio del Roque de los Muchachos, located on the island of La Palma. Image Credit: IAC

As Alejandro Suárez Mascareño explained in an IAC press release:

As GJ 625 is a relatively cool star the planet is situated at the edge of its habitability zone, in which liquid water can exist on its surface. In fact, depending on the cloud cover of its atmosphere and on its rotation, it could potentially be habitable.

This is not the first time that the HADES project detected an exoplanet around a red dwarf star. In fact, back in 2016, a team of international researchers used this project to discover two super-Earths orbiting GJ 3998, a red dwarf located about 58 ± 2.28 light years from Earth. Beyond HADES, this discovery is yet another in a long line of rocky exoplanets that have been discovered in the habitable zone of a nearby red dwarf star.

Such findings are very encouraging since red dwarfs are the most common type of star in the known Universe — accounting for an estimated 70% of stars in our galaxy alone. Combined with the fact that they can exist for up to 10 trillion years, red dwarf systems are considered a prime candidate in the search for habitable exoplanets.

But as with all other planets discovered around red dwarf stars, there are unresolved questions about how the star’s variability and stability could affect the planet. For starters, red dwarf stars are known to vary in brightness and periodically release gigantic flares. In addition, any planet close enough to be within the star’s habitable zone would likely be tidally-locked with it, meaning that one side would be exposed to a considerable amount of radiation.

Artist’s impression of of the exoplanets orbiting a red dwarf star. Image Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).

As such, additional observations will need to be made of this exoplanet candidate using the time-tested transit method. According to Jonay Hernández — a professor from the University of La Laguna, a researcher with the IAC and one of the co-authors on the study — future studies using this method will not only be able to confirm the planet’s existence and characterize it, but also determine if there are any other planets in the system.

“In the future, new observing campaigns of photometric observations will be essential to try to detect the transit of this planet across its star, given its proximity to the Sun,” he said. “There is a possibility that there are more rocky planets around GJ 625 in orbits which are nearer to, or further away from the star, and within the habitability zone, which we will keep on combing.”

According to Rafael Rebolo — one of the study’s co-authors from the Univeristy of La Laguna, a research with the IAC, and a member of the CSIS — future surveys using the transit method will also allow astronomers to determine with a fair degree of certainty whether or not GJ 625 b has the all-important ingredient for habitability — i.e. an atmosphere:

The detection of a transit will allow us to determine its radius and its density, and will allow us to characterize its atmosphere by the transmitted light observe using high resolution high stability spectrographs on the GTC or on telescopes of the next generation in the northern hemisphere, such as the Thirty Meter Telescope (TMT).

Artist’s impression of a system of exoplanets orbiting a low mass, red dwarf star. Image Credit: NASA/JPL

But what is perhaps most exciting about this latest find is how it adds to the population of extra-solar planets within our cosmic neighborhood. Given their proximity, each of these planets represent a major opportunity for research. And as Dr. Mascareño told Universe Today via email:

While we have already found more than 3600 extra-solar planets, the exoplanet population in our near neighborhood is still somewhat unknown. At 21 ly from the Sun, GJ 625 is one of the 100 nearest  stars, and right now GJ 625 b is one of the 30 nearest exoplanets detected and the 6th nearest potentially habitable exoplanet.

Once again, ongoing surveys of nearby star systems is providing plenty of potential targets in the search for life beyond our Solar System. And with both ground-based and space-based next-generation telescopes joining the search, we can expect to find many, many more candidates in the coming years. In the meantime, be sure to check out this animation of GJ 625 b and its parent star:

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Everything You Need to Know About NASA’s Epic 7-Planet Discovery Today

Alien Worlds

It wasn’t too long ago that we thought Earth was the only habitable planet in the universe. But recent advancements in space technology have led to the discovery of one exoplanet after another, leading to the conclusion that life must exist outside of Earth.

To date, astronomers have identified a few alien planets that could potentially support life. For example, five exoplanets that are particularly promising are Wolf 1061C, a rocky exoplanet about the size of the Earth that is 13,8 light years away; Gliese 832C, a larger planet dubbed a “super-Earth;” Gliese 667Cc, which is 22light-yearss away in the Scorpius constellation; TRAPPIST-1d located in the Aquarius constellation; and Gliese 163C in the Dorado constellation.

These five are some of the closest Earth-like planets in the habitable zone of their parent star, but they are by no means the only ones that have been identified. NASA has actually discovered more than 2,000 planets that could be home to alien life – but for the most part, we know very little about them.

Today, everything changed.

NASA just held a press conference announcing the discovery of a solar system that has a host of Earth-sized planets. Three of these are located firmly in the habitable zone, meaning that they very likely have liquid water and could host life.

Here’s everything you need to know about these finds.

Reddit AMA

According to NASA’s Reddit AMA, this discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. Here are the other highlights:

How long would it take with current technology to get to this solar system?

NASA: Right now, there is no current technology that can get us to the new planetary system. That’s why we will use space-based telescopes to “remotely” investigate by observing the planets from afar. To see fledgling efforts to send tiny space craft to a different star (with one known planet) see this link.

Do we know the gravity, compared to Earth or Mars, on those 3 planets that could have water in them?

NASA: Determining the surface gravity requires knowledge of both the radius and mass. The uncertainties on the mass measurements are large, but our best guess is that the surface gravity of most of these planets is similar to that on Earth. One exception is planet f. It has the same radius as Earth but 68% the mass. That means the surface gravity will be 68% lower than on Earth.

What is the protocol if you do find any signs of life on any of the exoplanets? How long would it probably take from time of discovery to an actual announcement to the public? 

NASA: We do not yet have a protocol. Most likely, we will make a tentative discovery that will take longer to confirm. But that is a great question, and something that has been thought about a lot by many different organizations. There is a great article on this by SETI scientist Dr. Duncan Forgan, which looks at many different scenarios in the age of 24-hour news and social media

Can we expect to have the technology in the next 20-30 years that we could see, for sure, that there would be life in those planets in form of vegetation?

NASA: In order to see vegetation and any other surface features (e.g. oceans, continents), we’ll need future telescopes beyond JWST [the James Webb Space Telescope, set to launch in 2018] that will be able to directly image exoplanets. JWST will observe planets transiting their host stars. Transits are when the planet passes between us and its star, and from these transits, we can observe how gasses in the planet’s atmosphere interact with starlight passing through the atmosphere. Unfortunately, this technique doesn’t allow us to see the surfaces of exoplanets. To do that, we’ll need future technology that may become available in the coming decades that will allow us to block out the star’s light and observe the planets directly. Examples of these technologies are starlight suppression tools called coronagraphs and starshades. The planets we observe directly with these starlight suppression techniques will not be spatially resolved: they will literally be single points of light, but don’t despair because we can still learn a lot from single points of light!

When should we expect the data/results around atmospheric composition to be released or published?

NASA: The first observations of the newly discovered planets are underway, as soon as the results successfully pass through the scientific peer review process we will be able to share what we are learning. Stay tuned this system has lots more exciting things to teach us.

How well can Kepler spacecraft detect planets around TRAPPIST-1 compared to Spitzer spacecraft? 

NASA: Kepler can observe for about 80 days consecutively and will, therefore, provide a very important time series and information on the gravitational interactions between the planets which cause timing variations. It is possible that there may be additional planets not seen by Spitzer in 20 days which Kepler could uncover. Kepler and Spitzer have comparable capabilities for the detection of planets around the TRAPPIST-1 system.

 

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