The Wide Field Infrared Survey Telescope (WFIRST) is a proposed infrared space observatory which was selected by National Research Council committee as the top priority for the next decade of astronomy. The WFIRST space telescope could be in space by 2024 if it is started in 2017.
Estimates suggested that every planetary system in the galaxy booted at least one planet into interstellar space. With billions of planetary systems in the Milky Way, there may be billions, maybe even hundreds of billions, of rogue planets in the galaxy, says planetary scientist Sara Seager of MIT.
“A census of rogues,” Liu says, “is the only way we are going to fully understand the extent of what’s out there in the Milky Way.”
Two traits distinguish a star from a brown dwarf and to an extent, from a planet: mass and the presence or absence of nuclear fusion. Stars, even small ones, are at least 80 times the mass of Jupiter, which at 318 times the mass of Earth is the most massive planet in the solar system — and is often used by astronomers to gauge the size of other gaseous objects. According to theoretical calculations about how stars work, objects must be 80 Jupiter masses or more to fuse hydrogen nuclei (protons) into helium. This process liberates energy, which is how stars burn bright, speckling the night sky.
Brown dwarfs are smaller, anywhere between 13 and 80 Jupiter masses. They are not dense enough to fuse hydrogen. But they may have been big and hot enough to fuse deuterium nuclei (a proton plus a neutron) with protons or other nuclei, which means they once generated energy but no longer do.
Any sphere less than about 13 Jupiter masses is not large or dense enough to fuse any kind of atomic nuclei. As a result, some astronomers define orbs with less than roughly 13 Jupiter masses — even untethered ones — as planets.
One study suggests there could be 100,000 rogue planets for every star in the Milky way.
Astronomy and Astrophysics - CFBDSIR2149-0403: a 4–7 Jupiter-mass free-floating planet in the young moving group AB Doradus?
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MASS MATTERS Small stars, brown dwarfs and rogue planets can be similar in diameter but have different masses. Mass is one characteristic used to distinguish the objects. However, for classification purposes, astronomers may need to look beyond mass to consider how an orb formed and what elements it’s made of.
FROM LEFT: JUT13/ISTOCKPHOTO; NASA; SEGRANSAN ET AL/A&A 2008; LEECH ET AL/ASP CONFERENCE SERIES 2000; LIU ET AL/APJ LETTERS 2013
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Estimates suggested that every planetary system in the galaxy booted at least one planet into interstellar space. With billions of planetary systems in the Milky Way, there may be billions, maybe even hundreds of billions, of rogue planets in the galaxy, says planetary scientist Sara Seager of MIT.
“A census of rogues,” Liu says, “is the only way we are going to fully understand the extent of what’s out there in the Milky Way.”
Two traits distinguish a star from a brown dwarf and to an extent, from a planet: mass and the presence or absence of nuclear fusion. Stars, even small ones, are at least 80 times the mass of Jupiter, which at 318 times the mass of Earth is the most massive planet in the solar system — and is often used by astronomers to gauge the size of other gaseous objects. According to theoretical calculations about how stars work, objects must be 80 Jupiter masses or more to fuse hydrogen nuclei (protons) into helium. This process liberates energy, which is how stars burn bright, speckling the night sky.
Brown dwarfs are smaller, anywhere between 13 and 80 Jupiter masses. They are not dense enough to fuse hydrogen. But they may have been big and hot enough to fuse deuterium nuclei (a proton plus a neutron) with protons or other nuclei, which means they once generated energy but no longer do.
Any sphere less than about 13 Jupiter masses is not large or dense enough to fuse any kind of atomic nuclei. As a result, some astronomers define orbs with less than roughly 13 Jupiter masses — even untethered ones — as planets.
One study suggests there could be 100,000 rogue planets for every star in the Milky way.
Astronomy and Astrophysics - CFBDSIR2149-0403: a 4–7 Jupiter-mass free-floating planet in the young moving group AB Doradus?
MASS MATTERS Small stars, brown dwarfs and rogue planets can be similar in diameter but have different masses. Mass is one characteristic used to distinguish the objects. However, for classification purposes, astronomers may need to look beyond mass to consider how an orb formed and what elements it’s made of.
FROM LEFT: JUT13/ISTOCKPHOTO; NASA; SEGRANSAN ET AL/A&A 2008; LEECH ET AL/ASP CONFERENCE SERIES 2000; LIU ET AL/APJ LETTERS 2013
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