If you were a farmer looking for eggs in the chicken coop, you may find an ostrich egg instead of a chicken egg since it is considerably bigger than anything a chicken could lay.
That’s how our astronomy team felt, too, when we found earlier this year a gigantic planet, more than 13 times heavier than Earth, orbiting a chilly, dim red star, nine times less massive than the Sun.
In addition to being smaller than the Sun in our solar system, the smaller star, known as a M star, is also 100 times less bright. It shouldn’t be possible for a star of this type to have the planet-forming disk material needed to support a planet this size.
The Planet Finder for Habitable Zones
Our team at Penn State has spent the last ten years developing and constructing a novel device that can detect light from these cool, dim stars at wavelengths that are infrared, which is beyond the range of human vision. This is where the majority of the light from these cool stars is emitted.
Our device, called the Habitable Zone Planet Finder, is mounted on the 10-meter Hobby-Eberly Telescope in West Texas. It is designed to monitor the minute change in a star’s velocity caused by a planet pulling on it. The Doppler radial velocity technique is an excellent method for exoplanet detection.
An “exoplanet” is any planet-sized entity that is in orbit around a star other than the Sun; the phrase is a combination of the words extrasolar and planet.
Thirty years ago, 51 Pegasi b, the first known exoplanet circling a Sun-like star, was discovered thanks to Doppler radial velocity studies. Over the next decades, we as astronomers have refined this method.
The identification of rocky planets in habitable zones—the areas around stars where liquid water can be sustained on the planetary surface—is one of the major objectives of these ever-more-accurate observations.
The current state of technology prevents the Doppler approach from finding Earth-mass planets orbiting Sun-sized stars that are in the habitable zone. However, a greater Doppler signature is seen in the cool, faint M stars for the same-sized planet as Earth.
The planet in orbit pulls on the star more forcefully because of its smaller mass. Additionally, a shorter orbit and a closer-in habitable zone result from the decreased illumination, which also facilitates planet detection.
Our team created the Habitable Zone Planet Finder with the purpose of finding planets orbiting these smaller stars. It was rather unexpected when we announced our latest discovery, which was detailed in the journal Science, of a large planet circling around the cool, faint M star LHS 3154, also known as the ostrich egg in the chicken coop.
LHS 3154b: The planet that should not exist
Gas and dust disks are where planets form. Dust grains are drawn together by these disks, eventually forming into pebbles and a solid planetary core.
After the planet’s core forms, solid dust and ambient gases like helium and hydrogen can be drawn in by the planet’s gravity. However, for this to work well, a lot of mass and materials are required. This process of planet formation is known as core accretion.
It is expected that a star with nine times the mass of the Sun, like LHS 3154, will have a low-mass planet formation disk.
Simply put, there shouldn’t be enough solid matter or mass in a normal disk orbiting a low-mass star to be able to form a core heavy enough to form such a planet.
Our team’s computer simulations led us to the conclusion that a disk at least ten times as huge as what is usually inferred from direct observations of disks that create planets is necessary for the existence of such a planet.
An extremely huge disk is required to explain the formation of such a planet, which is incompatible with another hypothesis of planet formation called gravitational instability. In this theory, gas and dust in the disk directly collapse to create a planet.
Planets around the majority of stars
The most common stars in our galaxy are M stars, which are cool and faint. According to legend from DC comics, Superman’s home planet, Krypton, revolved around a M dwarf star.
Giant planets in close-in orbits around the most massive M stars are at least ten times uncommon than those orbiting Sun-like stars, according to findings made with the help of devices like the Habitable Zone Planet Finder.
Moreover, before the finding of LHS 3154b, we are unaware of any such big planets in close orbit around the least massive M stars.
We will be able to better grasp the formation of planets near our coolest neighbors if we can also comprehend the formation and evolution of rocky worlds around the majority of star types. Astronomers may be able to learn more about whether M stars can sustain life by following this line of inquiry.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
