Draft:H dwarf

  • Comment: I think the topic is fantastic but, it still need more than one source to pass WP:GNG and WP:NASTRO Abdullah1099 (talk) 17:22, 27 March 2026 (UTC)
  • Comment: interesting; would be great to see some secondary sources. Astropedian (talk) 11:14, 1 March 2026 (UTC)

An object with a spectral type H (also called H dwarf or hydrocarbon brown dwarf)[1] is either a brown dwarf or a free-floating planetary mass object. They have a extremely low-mass for brown dwarfs (under the deuterium burning limit), and are predicted to be colder than Y dwarfs.[1][2]

An image of the IC 348 star-forming region, where two H-type dwarfs have been identified

Characteristics

The spectral type H was first suggested in June 2025 by astronomers, Kevin Luhman and Catarina Alves de Oliveira after they discovered two unusual brown dwarfs.[1] They are characterized by a presence of unknown aliphatic hydrocarbon in their atmospheres, and an absorption line at 3.4-3.5 μm.[1]

H-type dwarfs have very low masses for brown dwarfs with a mass between 2 and 10MJ (≤0.075 M⊙).[1][3] The least massive H-type dwarf is approximately the same mass as Jupiter, making them the least massive brown dwarf spectral type.[1] However, the least massive L-type dwarfs such as 2M1207 b have similar properties to H-type dwarfs.[1]

Only two candidate H-type dwarfs have been found which are designated LRL 11001, and LRL 11003.[1] There absorption lines are similar to the diffuse interstellar medium (also known as the ISM).[1] Although, these two brown dwarfs may be H-type dwarfs they also have a similar spectra and properties to L-type dwarfs.[1]

Location

Using the James Webb Space Telescope (JWST), Luhman and Alves de Oliveira were able to identify two potential H-type dwarfs in the IC 348 star-forming region.[1][3] No other H-type dwarfs have been discovered in other regions, but there are predicted to exist in NGC 2024 (also referred to as the Flame Nebula), and the TW Hydrae association.[1]

References

  1. ^ a b c d e f g h i j k l Luhman, Kevin (2025). "A New Spectral Class of Brown Dwarfs at the Bottom of the IMF in IC 348". The Astrophysical Journal Letters. 986 (1): L14. arXiv:2506.08969. Bibcode:2025ApJ...986L..14L. doi:10.3847/2041-8213/addc55.
  2. ^ Hensley, Kerry (2025-07-14). "Featured Image: Low-Mass Brown Dwarfs in a Class of Their Own?". AAS Nova. Retrieved 2026-04-24.
  3. ^ a b Morales-Calderón, María; Jang, Hyerin; Arabhavi, Aditya M.; Christiaens, Valentin; Barrado, David; Kamp, Inga; Dishoeck, Ewine F. van; Henning, Thomas; Waters, L. B. F. M.; Temmink, Milou; Güdel, Manuel; Lagage, Pierre-Olivier; Garatti, Alessio Caratti o; Glauser, Adrian M.; Ray, Tom P. (2025-11-01). "MINDS - Cha Hα 1, a brown dwarf with a hydrocarbon-rich disk". Astronomy & Astrophysics. 703: A18. doi:10.1051/0004-6361/202555621. ISSN 0004-6361.

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