Molecules can only exist in the atmospheres of very cool stars or in the cooler regions of stars higher in the main sequence, such as in sunspots in our own sun. Most of the observed species are diatomics and are often transitory. Brown dwarfs, on the other hand, can be cool enough to support complex molecules such as methane. Two spectral classes, L (~1300 to ~2000 K) and T (below ~1300 K), have been created for them. NOTE: Molecule identifications in the table below are intended to be representative, not exhaustive. As with any identification, certainties will vary; a molecule in italic font is a tentative detection. Sources indicate that about 25 species have been identified in the Sun. See also: The Classification of Stellar Spectra (an informative discussion on star type) and the Wikipedia article on spectral classes. |
OBJECT/TYPE | MOLECULES
(click for citation) | DISCOVERY/GENERAL CITATION |
Sun ("Sol")
![]() (G2V star) |
AlH
CaH
CH
CH+ CN CrH CuH H2 H2O HCl NH OH ScO SiH TiH TiO ZrO CO SH AlF |
On Molecules in Sunspots
H. Wöhl. Solar Phys 16:362 (1971). |
---|---|---|
DENIS J08173001- 6155158
![]() (T6 brown dwarf) |
CH4
H2O
NH3
H2 H2S |
DENIS J081730.0-615520: An Overlooked Mid-T Dwarf in the Solar Neighborhood
É. Artigau, J. Radigan, S. Folkes, R. Jayawardhana, R. Kurtev, D. Lafrenière, R. Doyon, and J. Borissova. ApJL 718:L38 (2010). |
ε Indi Ba
![]() (T brown dwarf) | CH4 H2O CO |
ε Indi B: A New Benchmark T Dwarf
R. D. Scholz, M. J. McCaughrean, N. Lodieu, and B. Kuhlbrodt. A&A 398:L29 (2003). |
IK Tauri
![]() (Mira variable star) |
CO
HCN
SiO
SiS SO SO2 H2S NaCl NS NO PO HCO+ PN H2O H2CO AlOH AlO AlCl (Al2O3)n AlF |
Observations of Extremely Cool Stars
G. Neugebauer, D. E. Martz, and R. B. Leighton. ApJ 142:399 (1965). |
IRAS 12311-3509 (N star) | SiC2 |
IRAS 12311-3509: A Carbon Star with SiC2 Emission
T. Lloyd Evans, M. E. Hurst, and P. J. Sarre. MNRAS 319:111 (2000). |
GD 165B
![]() (L brown dwarf) | CrH FeH |
The Unique Spectrum of the Brown Dwarf Candidate GD 165B and Comparison to the Spectra of
Other Low-Luminosity Objects
J. D. Kirkpatrick, T. J. Henry, and J. Liebert. ApJ 406:701 (1993). |
Gliese 229B
![]() (T brown dwarf) | CH4 H2O CO |
Discovery of a Cool Brown Dwarf
T. Nakajima, B. R. Oppenheimer, S. R. Kulkarni, D. A. Golimowski, K. Matthews, and S. T. Durrance. Nature 378:463 (1995). |
Gliese 570D
![]() (T7.5 brown dwarf) | CH4 H2O NH3 |
Discovery of a Brown Dwarf Companion to Gliese 570ABC: A 2MASS T Dwarf Significantly Cooler than Gliese 229B
A. J. Burgasser, J. D. Kirkpatrick, R. M. Cutri, H. McCallon, G. Kopan, J. E. Gizis, J. Liebert, I. N. Reid, M. E. Brown, D. G. Monet, C. C. Dahn, C. A. Beichman, and M. F. Skrutskie. ApJ 531:L57 (2000). |
Mira (ο Ceti)
![]() (M star) | TiO VO AlF |
Maxima of ο Ceti and Other Variables
R. O'Halloran. Publ Astron Soc Pac 11:246 (1899). |
Proxima Centauri
![]() (M5.5Ve red dwarf) | AlH |
A Faint Star of Large Proper Motion
R. T. A. Innes. Circular of the Union Observatory Johannesburg. 30:235 (1915). |
R Andromedae
![]() (S star) | CeO SH |
Über helle Linien im Spectrum von R Andromedae
T. E. Espin. Astronomische Nachrichten 123:31 (1890). |
VY Canis Majoris
![]() (M star, red hypergiant) |
AlO
ScO
TiO
VO NaCl | Cataloged by Lalande 7 March 1801. |
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