Stars the size of our sun are not the most common in the Milky Way galaxy. Much smaller stars are much more common. Of all the stars in our country galaxythese little stars HOST more planets. Scientists are studying the planets of these small stars in search of worlds that could support life.
New research is providing insight into how planets form around these small stars, called very-low-mass stars, or VLMS. Chemistry of planet formation discs the gas and dust surrounding them is different from similar disks observed around stars like the sun.
The James Webb Space Telescope has collected data on a planet-forming disk, or protoplanetary, around a newborn star called ISO-Chal 147. It’s only about 11 percent the mass of the sun. Its diameter is about 43 percent that of the sun and its luminosity is about two percent that of the sun. Radiance is a measure of electromagnetic radiation.
ISO-Chal 147 is about 625 light years from Earth. A light year, the distance light travels in one year, is 9.5 trillion kilometers.
Webb’s observations showed that the gas in the protoplanetary disk of this star is rich in carbon with no evidence of water. This differs from young Sun-like stars, which have oxygen-rich gas and lots of water STEAM on their drives.
Scientists wonder if this change could affect the future habitability of rocky planets forming around these small stars.
“A planet primarily requires, among other things, that water be in a liquid state and have a suitable atmosphere for it to be habitable,” said astrophysicist Aditya Arabhavi of the University of Groningen in the Netherlands, who was lead author of the study recently published in science.
“Although we can expect the different environment of the VLMS disks to have a strong impact on the planets Compound and thus habitability, it’s hard to predict whether that makes it less likely to be habitable,” Arabhavi said.
Stars form when dense regions of gas and dust collapse under their gravitational pull. After a star appears at the center of such a cloud, the remaining material forms in a rotating disk around it. This activity fuels the growth of stars and often leads to the formation of planets.
The disks around very young sun-sized stars contain much more material than those around smaller stars. This means that bigger stars are more likely to have “gas giant” planets around them. This is the case with the sun and its planets Jupiter and Saturn.
VLMS are “the most common stars in our Milky Way,” said astrophysicist and study co-author Thomas Henning of the Max Planck Institute for Astronomy in Germany.
“These objects are currently targets in the search for rocky planets because they are easier to find around such stars. Furthermore, the masses of their planet-forming disks are generally too small to form planets. giants, but big enough to form planets,” Henning said.
Scientists have already identified rocky planets orbiting very low-mass stars, including some that orbit at just the right distance to support life.
“I would expect planets to remain habitable if they are in area where liquid water can exist,” said Henning.
Still very young, ISO-Chal 147 may become a very low-mass type of star called a red dwarf. The diameter of the star is only about four times that of Jupiter. The diameter of our sun is about 10 times that of Jupiter.
Webb, which began operating in 2022, also identified ethane in the protoplanetary disk of ISO-Chal 147. The discovery marks the first time the gas has been found outside our own star system. The research also found other carbonaceous gases never seen before in such a disk.
“Webb is certainly helping us by providing invaluable data that was never possible before,” said Arabhavi.
I’m Caty Weaver.
Caty Weaver adapted this story for VOA to learn English based on reporting by Will Dunham of Reuters.
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The words in this story
galaxy – n. a large group of stars and planets
HOST – v. to be a place where something can be found
disc – n. a round, flattened shape
STEAM – n. a gas
habitability – n. the ability to support life
suitable – adjective. something that is right for a particular situation
Compound – n. what something is made of
area – n. an area that is different from the others for a specific reason
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