Sentences with word «subdwarf»

Unusually faint for its spectral type, Groombridge 1830 is a yellow - orange halo subdwarf star of spectral and luminosity type sdG8p / VI.

In 1998, nine Sol - type stars (naked - eye objects Omicron Aquilae, Kappa Ceti, and Pi1 Ursae Majoris, as well as MQ / 5 Serpentis, UU Coronae Borealis, S Fornacis, MT Tauri, BD +10 2783, and Groombridge 1830 — now believed to be a single, Halo subdwarf without a «flare star» companion) were found to have produced superflares, on average, about once per century.

We determine typical colors of M0 - T9 dwarfs, and we highlight the distinctive colors of subdwarfs and young objects.

The star may even be suspected of being a dim subdwarf (sd / VI)-- like Groombridge 1830 or Kapteyn's Star — rather than a main - sequence dwarf star (V).

Kapteyn's Star is a dim red subdwarf or main sequence (sdM0 - 1.5 or V), halo star (John E. Gizis, 1997, page 809; and NASA Star and Exoplanet Database), which is thought to be originally a member of the Milky Way galaxy's luminous halo.

The stars may be passing through a stage of stellar evolution that lasts no more than a few tens of thousands of years, the scientists say — a phase between red giants (about 30 or 40 times the size of our sun) and blue subdwarfs (stars about one - fifth the size of our sun but seven times hotter and 70 times brighter).

We analyze the kinematics of ultracool dwarfs in our catalog and find evidence that bluer but otherwise generic late - M and L field dwarfs (i.e., not subdwarfs) tend to have higher tangential velocities compared to typical field objects.

Known as subdwarfs, these stars are also fusing hydrogen in their core and so they mark the lower edge of the main sequence's fuzziness resulting from chemical composition.

Once thought to be old Population II, galactic - halo - type subdwarf stars, Zeta1 and its companion are more likely to be old disk stars (Da Silva and Foy, 1987), that may be as much as eight billion years old, but more recent analysis of chromospheric activity and rotation with spectral analysis and calibration with other Sol - type stars suggest that the two stars could be as young as 1.5 to three billion years old (Mamajek and Hillenbrand, 2008, Table 13).

The central star of M27 is quite bright at mag 13.5, and an extremely hot blueish subdwarf dwarf at about 85,000 K (so the spectral type is given as O7 in the Sky Catalog 2000).

The star is at least 5.4 billion years old based on chromospheric anaysis alone (Don C. Barry, 1998, page 3), but its halo subdwarf status would suggest that the star is at least 10 billion years old, having formed during a period of rapid collapse that lasted perhaps a billion years in the early history of the Milky Way galaxy prior the development of the galactic disk.

Charpinet, S., Fontaine, G., Brassard, P., Chayer, P., Rogers, F.J., Iglesias, C.A. and dorman, B. (1997) A driving mechanism for the newly discovered class of pulsating subdwarf B stars.

Astronomers had found 15 subdwarfs in the Solar neighborhood by 1998 (Fuchs and Jahreiß, 1998).

NASA — larger image Kapteyn's Star is a very dim red subdwarf, somewhat bluer and dimmer than Gliese 623 A (M2.5 V) and B (M5.8 Ve) at lower right.

There is also an optical binary companion system of K5 and M2 dwarf / subdwarf stars — at about 122», according to the Yale Bright Star Catalogue, 1991 5th Revised Edition notes entry for HR 1457 — that were once referred to as Stars «C» and «D.» The stars in this system are separated by around 34 AUs, and they have a combined visual luminosity of about 1.1 percent of Sol's (Kyle M. Cudworth, 1985; and R.F. Griffin, 1985).

One of these, called the Groombridge 1830 group, consists of a number of subdwarfs and the star RR Lyrae, after which the RR Lyrae variables were named.