Astronomers have discovered a planet that’s 13 times more massive than Earth and orbits a star that’s nine times less massive than the Sun. The planet, named LHS 3154 b, is roughly on par with Neptune in mass. The star it orbits, LHS 3154, is an ultracool dwarf star.
The discovery may challenge current ideas about planet formation. The planet is also wrapped in metallic clouds made of titanium and silicates that reflect most incoming light back into space.
Researchers suggest that the planet could be investigated using the James Webb Space Telescope.
And the newest curveball wrecking the minds of the astronomy community is a pretty big one, orbiting a surprisingly tiny star. A team of astronomers has detected a planet more than 13 times as massive as Earth orbiting an ultracool dwarf star called LHS 3154, which is nine times less massive than the Sun.
LHS 3154 b is an exoplanet that orbits the star LHS 3154. The planet is 13.2 times more massive than Earth, which is similar to Neptune’s mass. LHS 3154 b orbits its star every 3.7 Earth days, which is much closer than Mercury is to the sun.
Here are some other details about LHS 3154 b:
- Orbit: LHS 3154 b orbits at about 2.3% of Earth’s orbital distance from the sun.
- Distance: LHS 3154 b is located about 51.4 light-years from our solar system.
- Star: LHS 3154 b orbits the star LHS 3154, which is nine times less massive than the sun.
- Mass: LHS 3154 b has a mass just above the cutoff of supporting hydrogen fusion to be considered a star.
A study published in the journal Science says that LHS 3154 b is the most massive known planet in a close orbit around a low-mass star
The planet, which is named LHS 3154 b and was reported today in Science, tips the scales at 13.2 times the mass of Earth or more — putting it roughly on par with Neptune’s 17.2 Earth masses. Yet, its host star has just 11 percent the mass of the Sun
In the annals of planet hunting, astronomers’ latest find is a bit of a head-scratcher: a giant exoplanet tightly orbiting a star so tiny, it’s hard to understand how the star could have birthed it.
Discovering LHS 3154 b
Stefánsson and his colleagues found the planet with the 10-meter Hobby-Eberly Telescope at McDonald Observatory in Texas as they surveyed very low-mass stars. The team had at their disposal a new near-infrared spectrograph called the Habitable-zone Planet Finder. In early 2020, they began observing the star LHS 3154, classifed as an M dwarf (the least massive spectral type of star). They soon saw hints of a periodic shift in its spectrum every 3.7 days — a telltale sign that the gravitational pull of a planet on a close-in orbit was causing the star to wobble
The first exoplanets were discovered in 1992 by Aleksander Wolszczan and Dale Frail. The two planets, named Poltergeist and Phobetor, orbited a pulsar called PSR B1257+12
LHS 3154 is an ultracool dwarf star that’s located about 51.4 light-years away from our solar system. It’s classified as an M dwarf, which is the least massive spectral type of star. LHS 3154 is nine times less massive than the sun.
LHS 3154 has a planet, LHS 3154 b, that’s Neptune-sized and too big for its star. The planet’s gravitational pull causes the star to wobble every 3.7 days.
Because LHS 3154 is an ultracool star, planets that could have liquid water on their surface would be much closer to their star. However, the discovery of LHS 3154 b challenges the prevailing planetary formation theory
M dwarfs are the smallest stars, with masses ranging from 50–8% of the Sun’s mass. They are also known as red dwarfs. M dwarfs are the most common stars in the galaxy, making up over 70% of all stars. They are relatively cool, with a surface temperature of less than 3600 K.
M dwarfs are smaller and less luminous than the Sun, so their habitable zone is closer in. The habitable zone is the area around a star where liquid water can exist on the surface of an orbiting planet. Early M dwarfs are considered likely places to find extra-solar planets within a habitable zone.
M dwarfs spend about 1010 years in the main sequence, which is enough time for complex life to develop on orbiting planets. However, the habitability of planets around M dwarfs is a hotly debated issue in astronomy
NASA’s Kepler mission suggests that M dwarfs have many rocky planets. The TRAPPIST-1 system is a late-M dwarf star with seven known planets. Three of these planets are in the habitable zone, and all have masses between 0.5 and 1.5 times Earth’s
M dwarfs are a good target for searching for habitable planets because:
- They are common: M dwarfs are the most common type of star in the universe.
- They are easy to detect: M dwarfs are small and dim, making it easier to detect planets orbiting them.
- They have long lifetimes: M dwarfs live for a long time.
- They have lower astrophysical noise: M dwarfs have less astrophysical noise than G and F type stars.
- They have a lower flux: M dwarfs have a lower flux than solar-like stars.
M dwarfs are also good targets for detecting low-mass rocky planets.
LHS 3154 is an ultracool dwarf star that’s nine times less massive than the Sun. It’s one of the least massive and coldest stars in the universe
Astronomers have discovered a planet orbiting LHS 3154 that’s 13 times more massive than Earth. The planet is Neptune-sized and is the first confirmation that ultracool dwarfs can form massive close-in planets
This discovery really drives home the point of just how little we know about the universe,” said Suvrath Mahadevan, the Verne M. Willaman Professor of Astronomy and Astrophysics at Penn State and co-author on the paper. “We wouldn’t expect a planet this heavy around such a low-mass star to exist.”
The researchers spotted the oversized planet, named LHS 3154b, using an astronomical spectrograph built at Penn State by a team of scientists led by Mahadevan. The instrument, called the Habitable Zone Planet Finder or HPF, was designed to detect planets orbiting the coolest stars outside our solar system with the potential for having liquid water — a key ingredient for life — on their surfaces.
Gas giant planets can form around M dwarfs through disc instability. This can happen if the discs have at least 30% of their host star’s mass during the initial stages of formation.
Other factors that can affect the formation of planets around M dwarfs include:
- Disk mass: More massive disks form more massive planets.
- Pebble size: Smaller pebbles delay the growth of super-Earths, allowing giant planet cores to form first.(full article source google)
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