Source: Hindu

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Context

• Astronomers have located a rocky exoplanet with an atmosphere, marking a significant discovery in the search for habitable worlds beyond our solar system.
• This rocky planet, known as 55 Cancri e or Janssen, orbits a star in the constellation Cancer, approximately 41 light-years away from Earth.

Details

Characteristics of 55 Cancri e

• Classified as a "super-Earth," 55 Cancri e is larger than Earth but smaller than Neptune.
• It orbits its host star at a close distance, completing an orbit every 18 hours.
• The planet's surface is estimated to be molten rock, with temperatures reaching 3,140 degrees Fahrenheit (1,725 degrees Celsius/2,000 degrees Kelvin).
• 55 Cancri e is likely tidally locked, meaning one side of the planet always faces its host star.
• With scorching surface temperatures and inhospitable conditions, 55 Cancri e is one of the hottest rocky exoplanets known.

Atmosphere Composition:

• Infrared observations using instruments aboard the James Webb Space Telescope revealed the presence of a substantial atmosphere around 55 Cancri e.
• The atmosphere is likely rich in carbon dioxide or carbon monoxide, with the possibility of other gases such as water vapor and sulfur dioxide.
• The exact thickness of the atmosphere remains uncertain, but it could be comparable to Earth's or even thicker than Venus' dense atmosphere.
• Due to its extreme temperatures and lack of liquid water, 55 Cancri e is deemed uninhabitable for life as we know it.

About Super-Earth Exoplanets

• Super-Earths are a class of exoplanets that are larger than Earth but smaller than Neptune, with masses typically ranging from 1 to 10 times that of Earth. 

Characteristics of Super-Earths:

• Super-Earths have masses and radii larger than Earth's but smaller than gas giants like Neptune.
• While some super-Earths may have rocky compositions similar to Earth, others may contain significant amounts of water, ice, or gases.
• Some super-Earths may possess atmospheres, which can vary in composition and thickness, impacting their potential habitability.

Detection Methods:

• Transit Method: Super-Earths are often detected using the transit method, which observes the slight dimming of a star's light as a planet passes in front of it.
• Radial Velocity Method: Variations in a star's radial velocity caused by the gravitational pull of an orbiting super-Earth can also indicate the presence of these exoplanets.
• Direct Imaging: Advanced telescopes may directly image super-Earths, although this method is challenging due to the planets' small size and proximity to their host stars.

Notable Examples of Super-Earths:

• Kepler-452b: Dubbed "Earth's cousin," Kepler-452b is located in the habitable zone of its star and shares similarities with Earth in terms of size and orbital period.
• Gliese 581d: Gliese 581d is a potentially habitable super-Earth orbiting within the habitable zone of its red dwarf star, although its exact composition and atmosphere remain uncertain.

Sources:

Hindu

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