EARTH LIKE PLANETS-2 (ELP-2)

Hope you’ve seen my previous blog on earth like planets. I’ve listed a few of them but there are plenty more which needs to be listed and more which are currently under observation.

As we all see it daily; we’re aiming for the mars for now. Thanks to ELON, interplanetary travel might become true one day. Form interplanetary to inter-galactic. Most of the ELP which are found are from our own galaxy i.e with required technology, we might be able to land upon other planets and settle there. Science fiction is bound to become a scientific reality one day. If not now, the future generations would be having PLANET as a record on their passports :P.

Have a look at few of these ELP.

KIC-7340288 b

Officially named KIC-7340288 b, the planet discovered by Kunimoto is just 1 ½ times the size of Earth – small enough to be considered rocky, instead of gaseous like the giant planets of the Solar System – and in the habitable zone of its star.

“This planet is about a thousand light years away, so we’re not getting there anytime soon!” said Kunimoto, a PhD candidate in the department of physics and astronomy. “But this is a really exciting find, since there have only been 15 small, confirmed planets in the Habitable Zone found in Kepler data so far.”

The planet has a year that is 142 ½ days long, orbiting its star at 0.444 Astronomical Units (AU, the distance between Earth and our Sun) – just bigger than Mercury’s orbit in our Solar System, and gets about a third of the light Earth gets from the Sun.

Kepler-9d

Kepler-9d, formerly known as KOI-377.03, is a planet in orbit around the sun-like star Kepler-9. Initially discovered by Kepler spacecraft, a terrestrial planet-searching satellite built and operated by NASA, Kepler-9d is most likely a Super-Earth, with an estimated radius approximately 60% larger than that of Earth’s, although its exact mass cannot be determined.

 Kepler-9d orbits Kepler-9 every 1.56 days at a distance of .0273 AU from its star, an extremely close distance. Although Kepler-9d is the closest planet to its star in its system, it is named Kepler-9d instead of Kepler-9b because two gas giants, Kepler-9b and Kepler-9c, were confirmed first.

The original studies into the system first suggested that Kepler-9d might be a planet, but a follow-up investigation made by the Kepler team later confirmed that it was; the confirmation of Kepler-9d as a planet was made public with the team’s paper, which was published in the Astrophysical Journal on January 1, 2011. The team used telescopes at the W.M. Keck Observatory in Hawaii to follow up on the Kepler space telescope’s initial discovery.

Kepler-186f

NASA’s Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in the “habitable zone” — the range of distance from a star where liquid water might pool on the surface of an orbiting planet. The discovery of Kepler-186f confirms that planets the size of Earth exists in the habitable zone of stars other than our sun.

While planets have previously been found in the habitable zone, they are all at least 40% larger in size than Earth and understanding their makeup is challenging. Kepler-186f is more reminiscent of Earth.

Kepler-186f resides in the Kepler-186 system, about 500 light-years from Earth in the constellation Cygnus. The system is also home to four companion planets, which orbit a star half the size and mass of our sun. The star is classified as an M dwarf, or red dwarf, a class of stars that makes up 70% of the stars in the Milky Way galaxy.

“M dwarfs are the most numerous stars,” said Quintana. “The first signs of other life in the galaxy may well come from planets orbiting an M dwarf.”

Kepler-186f orbits its star once every 130-days and receives one-third the energy from its star that Earth gets from the sun, placing it nearer the outer edge of the habitable zone. On the surface of Kepler-186f, the brightness of its star at high noon is only as bright as our sun appears to us about an hour before sunset.

Being in the habitable zone does not mean we know this planet is habitable. The temperature on the planet is strongly dependent on what kind of atmosphere the planet has,” said Thomas Barclay, research scientist at the Bay Area Environmental Research Institute at Ames, and co-author of the paper. “Kepler-186f can be thought of as an Earth-cousin rather than an Earth-twin. It has many properties that resemble Earth.”

The four companion planets, Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e, whiz around their sun every four, seven, 13, and 22 days, respectively, making them too hot for life as we know it. These four inner planets all measure less than 1.5 times the size of Earth.

The next steps in the search for distant life include looking for true Earth-twins — Earth-size planets orbiting within the habitable zone of a sun-like star — and measuring their chemical compositions. The Kepler Space Telescope, which simultaneously and continuously measured the brightness of more than 150,000 stars, is NASA’s first mission capable of detecting Earth-size planets around stars like our sun.

TRAPPIST-1e

Some 40 light-years from Earth, a planet called TRAPPIST-1e offers a heart-stopping view: brilliant objects in a red sky, looming like larger and smaller versions of our own moon. But these are no moons. They are other Earth-sized planets in a spectacular planetary system outside our own. These seven rocky worlds huddle around their small, dim, red star, like a family around a campfire. Any of them could harbour liquid water, but the planet shown here, fourth from the TRAPPIST-1 star, is in the habitable zone, the area around the star where liquid water is most likely to be detected. This system was revealed by the TRAnsiting Planets and PlanetIsmals Small Telescope (TRAPPIST) and NASA’s Spitzer Space Telescope. The planets are also excellent targets for NASA’s James Webb Space Telescope.

One of seven planets orbiting a small star, TRAPPIST-1, may be capable of supporting life as we know it on Earth, new climate models suggest. 

Located 39 light-years away from Earth, TRAPPIST-1 is a relatively cool M-dwarf star with about 9 % the mass of Earth’s sun and about 12 % its radius. This ultra-cool star is believed to host at least seven rocky planets that are about the size of Earth or smaller.

Using terrestrial climate and photochemistry models, researchers from the University of Washington (UW) simulated environmental states for each planet of the TRAPPIST-1 system. The models show that all seven exoplanets likely evolved like Venus, meaning that any water or oceans would have evaporated early on in the system’s formation, the research team said in a statement. 

According to these models, the seven planets of TRAPPIST-1 would have dense, uninhabitable atmospheres. However, one of the worlds, called TRAPPIST-1e, may host liquid water on its surface and, as a result, be able to support Earth-like life, according to the statement. 

“We are modelling unfamiliar atmospheres, not just assuming that the things we see in the solar system will look the same way around another star,” Andrew Lincowski, a UW doctoral student and lead author of the study, said in the statement. “We conducted this research to show what these different types of atmospheres could look like.”

It was one of seven new exoplanets to be discovered orbiting the star using observations from the Spitzer Space Telescope. The exoplanet is within the star’s habitable zone. Since its initial announcement, the physical characteristics have become better defined, allowing scientists to better understand its nature. TRAPPIST-1e is very similar to Earth, with just about the same mass, radius, density, gravity, temperature, and stellar flux. It is also confirmed to have a compact atmosphere like the terrestrial planets in our solar system.

More detailed studies of TRAPPIST-1e and the other TRAPPIST-1 planets released in 2018 determined that the planet is one of the most Earth-sized worlds found, with 91% the radius, 77% the mass, 102.4% the density (5.65 g/cm3), and 93% the surface gravity. TRAPPIST-1e is confirmed to be a terrestrial planet with a solid, rocky surface. It is cool enough for liquid water to pool on the surface, but not too cold for it to freeze like on TRAPPIST-1f, g, and h.

The planet receives a stellar flux 0.604 times that of Earth, about a third lower than that of Earth but significantly more than that of Mars. Its equilibrium temperature ranges from 225 K (−48 °C; −55 °F)to 246.1 K (−27.1 °C; −16.7 °F), depending on how much light the planet reflects into space. Both of these are between those of Earth and Mars as well.

TRAPPIST-1e is confirmed to have a compact, hydrogen-free atmosphere like those of our Solar System’s rocky planets, further raising the chances of habitability. Hydrogen is a powerful greenhouse gas, so if there was enough to be easily detected, it would mean that the surface of TRAPPIST-1e would be inhospitable. Since such an atmosphere is not present, it raises the chances for the planet to have a more Earth-like atmosphere instead. As it is one of the most promising potentially habitable exoplanets known, TRAPPIST-1e will be an early target of the James Webb Space Telescope. Planned for launch in March 2021, the telescope will allow more extensive analysis of the planet’s atmosphere, facilitating the search for any chemical signs of life, or biosignatures.

Kepler-20e 

NASA’s Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet’s surface, but they are the smallest exoplanets ever confirmed around a star like our sun.

Kepler-20e is the first planet smaller than the Earth discovered to orbit a star other than the sun. A year on Kepler-20e only lasts 6 days, as it is much closer to its host star than the Earth is to the sun. The temperature at the surface of the planet, around 1400 degrees Fahrenheit, is much hot to support life, as we know it.

Kepler-20e is likely to be entirely rocky and without an atmosphere. The planet is tidally locked, always showing the same side to its host star, as the moon to the Earth, and could have large temperature differences between its permanent night and day sides.

Astronomers think that the planet is likely to be geologically active, due to its own formation process and the strong gravitational interactions with its host star. In this artistic depiction, the planet is represented with active volcanoes on both the night and day sides.Kepler-20 is a star 929 light-years from Earth in the constellation Lyra with a system of five known planets.The apparent magnitude of this star is 12.51, so it cannot be seen with the unaided eye.  

It is slightly smaller than the Sun, with 94% of the Sun’s radius and about 91% of the Sun’s mass. The effective temperature of the photosphere is slightly cooler than that of the Sun at 5466 K, giving it the characteristic yellow hue of a stellar class G8 star. The abundance of elements other than hydrogen or helium, what astronomers term the metallicity, is approximately the same as in the Sun. It may be older than the Sun, although the margin of error here is relatively large.

Proxima b

Proxima Centauri b is a super Earth exoplanet that orbits a M-type star. Its mass is 1.27 Earths, it takes 11.2 days to complete one orbit of its star, and is 0.0485 AU from its star. Its discovery was announced in 2016.

The discovery of a roughly Earth-size planet around Proxima Centauri, the nearest star to Earth, has generated a lot of buzz, and even speculation that a robotic probe may visit the world in the coming decades.

But “Earth-size” is a very different thing than “Earth-like.” Even though the newfound planet, known as Proxima b, appears to orbit in its star’s habitable zone — the range of distances where water could exist in liquid form — nobody knows if it’s actually capable of supporting life.

Rory Barnes, a professor of astronomy at the University of Washington, stressed this point in an essay posted on palereddot.org, the website dedicated to the discovery team’s search for a planet around Proxima Centauri. 

If Proxima b formed relatively far away from the star (and later migrated inward to its present position), then it has a better chance of being ice-rich, ensuring a plentiful supply of water.  But if the world formed closer in, much or all of its water may have been heated to vapor and lost. Or the planet could have formed with lots of water, lost it, and then had more delivered to it by comets and/or asteroids, as the Earth did.

It is not at all clear which is true.

“It is entirely possible that this planet has water, but we cannot be certain,” Barnes wrote.

So, what’s the bottom line? Is Proxima Centauri b habitable or not?

“It’s complicated,” Barnes wrote.

Proxima b may be the closest of the thousands of exoplanets – which are planets orbiting stars outside our solar system – discovered to date, but at 4.2 light years away the prospect of a quick visit to find any Proximese aliens is still remote. Based on spacecraft today, a probe launched now would take around 70,000 years to reach the new planet.

That’s all for now. There are plenty other exo-planets and earth like planets orbiting other stars. Links to the above planets and various planets are available below. Hope you like it. ENJOY!.

REFERENCES:
https://en.wikipedia.org/wiki/Earth_analog
https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets
http://phl.upr.edu/projects/habitable-exoplanets-catalog
https://exoplanets.nasa.gov/exoplanet-catalog/1804/kepler-9-d/
https://en.wikipedia.org/wiki/Kepler-9d
https://arxiv.org/abs/1905.04426
https://www.nasa.gov/ames/kepler/nasas-kepler-discovers-first-earth-size-planet-in-the-habitable-zone-of-another-star
https://arxiv.org/abs/1404.5667
https://arxiv.org/abs/2002.10950
https://www.space.com/42512-trappist-1-planet-could-host-life.html
http://exoplanet.eu/catalog/trappist-1_e/
https://www.nasa.gov/mission_pages/kepler/multimedia/images/kepler-20e.html
https://arxiv.org/abs/1905.04309
https://www.theguardian.com/science/2016/aug/24/earth-like-planet-found-orbiting-our-suns-nearest-star-raises-hopes-for-life-proxima-b
https://www.space.com/33915-newfound-planet-proxima-b-habitability.html
https://arxiv.org/abs/1905.01336
How to characterize habitable worlds and signs of life –àhttps://arxiv.org/abs/1911.05597

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