TW Hydrae association

The TW Hydrae association is a group of very young low-mass stars and substellar objects located approximately 25–75 parsecs (80–240 light years) from Earth. They share a common motion and appear to all be roughly the same age, 10±3 million years old. It is the youngest such association within 100 pc from Earth.^[1]

As of 2017, 42 objects (in 23 systems^[2]) are assigned to the association confidently, and several dozens — uncertainly. Masses of its known members vary from 5 Jupiter masses to 2 solar masses, and their spectral types vary from A0 to L7.^[1]

Some of the best studied members of this stellar association are TW Hydrae (nearest known accreting T Tauri star to the Earth), HR 4796 (an A-type star with resolved dusty debris disk; the most massive known group member), HD 98800 (a quadruple star system with debris disk), and 2M1207 (accreting brown dwarf with remarkable planetary-mass companion 2M1207b).

Included in the association is WISEA 1147, which is a brown dwarf.^[3][4][5]

See also

• List of nearby stellar associations and moving groups
• β Pictoris moving group
• AB Doradus moving group
• Scorpius–Centaurus association

References

1. Gagné, J.; Faherty, J. K.; Mamajek, E. E.; et al. (2017). "BANYAN. IX. The Initial Mass Function and Planetary-mass Object Space Density of the TW HYA Association". The Astrophysical Journal Supplement Series. 228 (2): 1–62 (look p. 26, 35). arXiv:1612.02881. Bibcode:2017ApJS..228...18G. doi:10.3847/1538-4365/228/2/18.
2. Singular objects are also regarded as "systems" here.
3. Newcomb, Alyssa (20 April 2016). "Lonely Planet Unattached to a Star Found in Deep Space". ABC News. Retrieved 21 April 2016.
4. "Lone Planetary-Mass Object Found in Family of Stars". NASA. 19 April 2016. Retrieved 21 April 2016.
5. Kennell, Joanne. "Astronomers Spot a Lonely Planet-Like Object Floating Freely in Space". The Science Explorer. Retrieved 21 April 2016.