Atmosphere Found on TNO 2002 XV93, Second After Pluto
Why in the news
Astronomers found a faint gas layer around a small icy Kuiper Belt body, which challenges ideas about how little worlds hold on to atmospheres.
Key facts
- Object: (612533) 2002 XV93, a Trans-Neptunian Object in the Kuiper Belt.
- Status: second TNO with an atmosphere; Pluto was first.
- Method: stellar occultation, watching the object pass in front of a distant star.
- Size and distance: about 500 km across; around 39.6 AU (about 3.7 billion miles) away.
- Density: 5 to 10 million times thinner than Earth’s air.
- Likely gases: nitrogen, methane or carbon monoxide.
- Possible sources: cryovolcanism or recent impact outgassing.
Background
- A TNO is any body orbiting beyond Neptune; a dwarf planet is a subset big enough to be rounded by its own gravity, such as Pluto or Eris. This object is too small to qualify.
- Cryovolcanoes erupt volatiles such as water, ammonia or methane ice instead of molten rock.
- The Kuiper Belt is a doughnut-shaped zone from Neptune’s orbit (30 AU) to about 50 AU, home to Pluto and short-period comets.
Significance
- Offers a look at the chemistry of the early solar system, about 4.5 billion years ago.
Exam angle
- First TNO with an atmosphere: Pluto; second: 2002 XV93.
- Technique: stellar occultation.
- Related terms: Kuiper Belt, AU, cryovolcanism, dwarf planet.