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	Subdwarf star -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-20)
		A subdwarf star, sometimes denoted by "sd", is luminosity class VI under the Yerkes spectral classification system.
		Subdwarfs are mostly (additional info and facts about Population II) Population II stars.
		A notable subdwarf is (additional info and facts about Kapteyn's star) Kapteyn's star, and another is (additional info and facts about Groombridge 1830) Groombridge 1830.
	www.absoluteastronomy.com /encyclopedia/s/su/subdwarf_star.htm (113 words)

	subdwarf Comparison Table (Site not responding. Last check: 2007-10-20)
		A nearby high-velocity M0 subdwarf that is both the nearest halo star to the Sun and the nearest star that orbits the Galaxy backward.
		Subdwarf B star with very broad and shallow Balmer lines; fewer lines of the Balmer series are visible than for normal dwarfs.
		Subdwarf O star showing few very broad and shallow Balmer lines and a very strong He II 4686 line.
	www.csi.uottawa.ca:4321 /astronomy/subdwarf_table.html (95 words)

	Hot subdwarf stars
		Hot subdwarf stars are generally believed to be helium burning stars (He core mass 0.50 solar masses), covered with a very thin hydrogen shell (about 0.02 solar masses).
		Hot subdwarf research in Bonn started with the purpose to find good background light sources for studies of gas in the halo of the Milky Way (interstellar matter) because they are blue, have clean spectra and exist at high galactic latitudes.
		We assume a unique mass of hot subdwarfs of 0.50 solar masses, as it is suggested by their distribution in the gravity-temperature plane.
	www.astro.uni-bonn.de /~webstw/science/stwsdb.html (953 words)

	subdwarf concept from the Astronomy knowledge base (Site not responding. Last check: 2007-10-20)
		On the H-R diagram, subdwarfs lie slightly below the metal-rich Main Sequence, because they are fainter than metal-rich main-sequence stars of the same color.
		Subdwarfs are primarily Population II and lie just below the Main Sequence on the H-R diagram.
		Kapteyn's star (10 facts) (HD 33793, CD -45 1841) - A nearby high-velocity M0 subdwarf that is both the nearest halo star to the Sun and the nearest star that orbits the Galaxy backward.
	www.csi.uottawa.ca:4321 /astronomy/subdwarf.html (277 words)

	Reid's subdwarf fitting (Site not responding. Last check: 2007-10-20)
		The color-magnitude diagram defined by the stars in the sample is shown in figure 1, with stars of different abundance group in different symbols.
		Subdwarfs within different abundance bins are chosen to fit cluster main sequence with appropriate metallicity.
		Due to the steep slope of the main-sequence, it turns out that the inferred distance from this method is sensitive to the uncertainties in subdwarf colors.
	www.pha.jhu.edu /~qzhang/seminar2/node3.html (536 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		Gies calls the stripped-down star a subdwarf, a type of aging star that has passed the expansion phase - by swelling and puffing away its outer layers - and is on its way to becoming a fading white dwarf.
		The subdwarf would be the brightest object of its class in the sky (a sixth-magnitude star) if it could be seen alone.
		When the once-massive subdwarf entered its twilight years about 1 million years ago, for example, it swelled in size as it began using up its hydrogen fuel.
	ecf.hq.eso.org /stecf-pr-images/97-39.txt (1356 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		PG 0101+039 is a subdwarf B star located in the constellation of Andromeda at a distance of around 1000 light-years.
		Subdwarf B stars are around 5 times hotter than our Sun, and so dense that - at comparable masses - they are about 10 times smaller.
		Following the discovery of pulsating subdwarf B stars, it is now hoped that evolutionary theories can be constrained through the use of a technique called asteroseismology.
	www.astro.umontreal.ca /~casca/PR/Casca2005_Randall.html (477 words)

	Space Today Online: Deep Space -- Star Loss is Another's Gain
		The stripped-down star is a "subdwarf," a type of aging star that has passed the expansion phase by swelling and puffing away its outer layers and is on its way to becoming a fading "white dwarf" star.
		However, the beefed-up companion is ten times brighter in visible light than the subdwarf, which is lost in its glare and, therefore, eluded detection for many years.
		The subdwarf was detected by the Hubble Space Telescope's Goddard High Resolution Spectrograph (which was removed from Hubble February 1997 during the second servicing mission).
	www.spacetoday.org /DeepSpace/Stars/Binaries/LossGain.html (986 words)

	Subdwarf star - Encyclopedia Glossary Meaning Explanation Subdwarf star (Site not responding. Last check: 2007-10-20)
		Subdwarf star - Encyclopedia Glossary Meaning Explanation Subdwarf star.
		The term "subdwarf" was coined by Gerard Peter Kuiper in 1939, to refer to a series of stars with anomalous spectra that were previously labeled as "intermediate white dwarfs."(1) Often being members of the Milky Way's halo, they frequently have high space velocities relative to the Sun.
		A notable subdwarf is Kapteyn's star, and another is Groombridge 1830.
	www.encyclopedia-glossary.com /en/Subdwarf-star.html (222 words)

	Read about Subdwarf star at WorldVillage Encyclopedia. Research Subdwarf star and learn about Subdwarf star here! (Site not responding. Last check: 2007-10-20)
		luminosity 1.5 to 2 magnitudes lower than that of main-sequence stars of the same spectral type; this is due to subdwarfs having lower metallicity than other main sequence stars.
		Hertzsprung-Russell diagram subdwarfs appear to lie below the main sequence.
		The term "subdwarf" was coined by Gerard Peter Kuiper in 1939, to refer to a series of stars with anomalous spectra that were previously labeled as "intermediate
	encyclopedia.worldvillage.com /s/b/Subdwarf (219 words)

	Hubble - Life of Lively Duo
		Gies calls the stripped-down star a subdwarf, a type of aging star that has passed the expansion phase -- by swelling and puffing away its outer layers -- and is on its way to becoming a fading white dwarf.
		However, the beefed-up companion is ten times brighter in visible light than the subdwarf, which is lost in its glare and eluded detection for many years.
		The subdwarf was detected by the Hubble telescope's Goddard High Resolution Spectrograph (which was removed from Hubble last February during the second servicing mission), allowing scientists to identify its spectral signature.
	www.gsfc.nasa.gov /news-release/releases/1997/97-174.html (1091 words)

	The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources - I. The Bright Source Catalogue
		RE 1043+445: Identified with the hot, evolved star PG 1040+451, classified as a hot subdwarf (sdB) in the PG survey and more recently shown to be a possible hot DA white dwarf (Sansom et al., 1992).
		Because of the low signal-to-noise data the optical classification of this star is still uncertain, as indicated by the colon after the spectral type in table 1.
		RE 1236+475: Identified with the hot, evolved star PG 1234+482, classified as a hot subdwarf (sdOB) in the PG survey, and more recently shown to be a hot DA white dwarf (Jordan et al., 1991, Sansom et al., 1992).
	www.cs.wisc.edu /niagara/data/nasa/MNRAS_260_77.xml (19949 words)

	Chaboyer et al.'s subdwarf main sequence fitting (Site not responding. Last check: 2007-10-20)
		The metallicity range of the sample subdwarfs are mostly fit for the main sequence fitting for GC with -1.8 <[Fe/H]<-1.1.
		(1997), by ensuring that the mean metallicity of the subdwarf sample is close to that of the GC.
		[Fe/H] are used in weighted least squares fit, while the weighted mean abundance of these subdwarfs is -1.55, which is very similar to that of the cluster.
	www.pha.jhu.edu /~qzhang/seminar2/node5.html (211 words)

	Doctoral research project Asteroseismology of subdwarf B stars as a critical test for ...
		Doctoral research project Asteroseismology of subdwarf B stars as a critical test for...
		Asteroseismology of subdwarf B stars as a critical test for stellar evolution.
		We shall treat a single star, a close binary and a wide binary as these are the three end results of current evolutionary models of subdwarf B stars.
	www.kuleuven.ac.be /research/researchdatabase/project/3E05/3E050486.htm (171 words)

	A&A 317, 815-822 (1997) (Site not responding. Last check: 2007-10-20)
		An analysis of the observed properties of the subdwarf O6 close binary system HD 49798 and its 13.18s ultrasoft X-ray pulsating companion (WGA J0648.0-4418) is presented.
		On evolutionary grounds we show that the subdwarf must have a degenerate CO core and is in the phase of shell helium burning, which explains its high luminosity.
		We show that all observations are consistent with the X-ray source being a weakly magnetized massive white dwarf which is accreting matter from the wind of its subdwarf companion.
	www.phys.uu.nl /~pols/papers/hd49798.html (190 words)

	System Codes H04*
		Dust clouds and nebular remnants are common in the immediate area of the star, indicating that a previous generation of stars is long since gone, but this orange subdwarf is much younger than the other stars in the area.
		This blue subdwarf is fading fast, strongly indicating a probable future nova is imminent.
		One of hundreds of subdwarfs in this sector, this one is unusual only because it has captured a rogue asteroid at some point in the distant past.
	www.jestertrek.com /m64/mainmap/systems/h04.html (1334 words)

	[49.06] Hot Subdwarf Star Membership in Visual Binaries (Site not responding. Last check: 2007-10-20)
		Several per cent of these subdwarfs are found, on a statistical basis, to be reasonably convincing candidate members of wide binaries (common--proper--motion pairs of stars), and another several per cent are identified as possible c.p.m.\ candidates (wider separations, more crowded fields, etc.).
		In most cases, the red magnitude of the hot subdwarf and its proposed fellow traveler are similar, although this is partly a selection effect.
		We can nevertheless hope to exploit the (to--be--purified) sample to learn much about the luminosities, ages, and original metallicities of the hot subdwarf stars, and possibly their companions can be used as a kinematically unbiased sample of old disk stars.
	www.aas.org /publications/baas/v33n2/aas198/358.htm (234 words)

	Elizabeth M Green: Annual Report 2000 (Site not responding. Last check: 2007-10-20)
		Green continued the investigation of the origin and evolution of subdwarf B stars.
		Two complementary followup surveys were initiated: a spectroscopic survey to acquire radial velocities for the derivation of periods and velocity amplitudes of an unbiased sample of 30 to 50 post-common envelope subdwarf B binaries, and a photometric survey to obtain multiple 3-4 hr lightcurves to search for eclipses, reflection effects and ellipsoidal variables.
		Green, in collaboration with M. Reed and S. Kawaler (Iowa State University), serendipitously discovered what appears to be a new type of nonradial, multimode pulsation in subdwarf B stars, with periods of the order of an hour.
	www.as.arizona.edu /Astro/steward/annrep00/Elizabeth_Green.html (284 words)

	The detection of binary companions to subdwarf B stars (ResearchIndex)
		The detection of binary companions to subdwarf B stars
		Abstract: Intermediate dispersion spectroscopy of a sample of 40 hot subdwarf B stars between 5500 A and 9000 A has been obtained.
		The positive Ca ii identifications include known photometric binaries and new targets; all are associated with a photometric red excess.
	citeseer.ist.psu.edu /362287.html (200 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		The second meeting on hot subdwarf stars and related objects will be held in Santa Cruz de La Palma on the Canary Islands, and is organised in collaboration by the Isaac Newton Group of Telescopes and the Nordic Optical Telescope.
		Hot subdwarf stars and their relatives are believed to be important contributors to the hitherto mysterious UV upturn phenomenon in early-type galaxies; and a comprehensive investigation on this issue is being performed by the Galaxy Evolution Explorer (GALEX).
		Hot subdwarf stars are also a laboratory for studying the effects of diffusion, weak stellar winds, radiative levitation and gravitational settling.
	www.ing.iac.es /Astronomy/science/bulletin/20041201.html (634 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		Although there is not a universally accepted classification scheme for hot subdwarfs, it is fairly clear that the main criterion is a surface gravity higher than that of hot main sequence stars but less than that of hot white dwarfs.
		Probably this should be left until a clear picture of the evolution of hot subdwarf stars emerges.
		Originally the classes 'sd B' and 'sd O' were recognized by broad Balmer line absorption and the early confluence of the Balmer series; B types were classified by weak or non-existent helium lines and O types by the presence of HeII 4686 or other HeII lines (see e.
	xml.gsfc.nasa.gov /pub/adc/xml_archives/catalogs/3/3137/3137_readme.txt (1465 words)

	Subdwarf star - TheBestLinks.com - Main sequence, Star, Luminosity, Magnitude, ...
		Subdwarf star - TheBestLinks.com - Main sequence, Star, Luminosity, Magnitude,...
		Subdwarf star, Main sequence, Star, Luminosity, Magnitude, Spectral type...
		You can add this article to your own "watchlist" and receive e-mail notification about all changes in this page.
	www.thebestlinks.com /Subdwarf_star.html (131 words)

	Astron. Astrophys. 327, 577-586 (1997)
		The abundance of metals in subdwarf star atmospheres is possibly affected by upward convection of processed material but more likely by gravitational downward diffusion of the heavy elements.
		Our studies of hot subdwarf stars have two main goals: one is to determine the parameters and the evolutionary state of the subdwarf stars in the framework of stellar evolution; the other is to investigate the structure of the Milky Way using these stars.
		A relation between these two goals can be found in the connection between the age of subdwarf stars and their spatial distribution.
	aa.springer.de /papers/7327002/2300577/sc1.htm (506 words)

	National Science Foundation: Nearly-Naked Stars Boost the Pulse of Asteroseismology
		One problem is that most star cores are wrapped in a thick envelope of hydrogen gas that obscures any pulses that might occur.
		However, previous observations of the hottest subdwarf B stars revealed that their pulsations are weak and generally occur only minutes apart, making them hard to measure with conventional telescopes.
		Astronomer Elizabeth Green, working with undergraduates from the University of Arizona, has been observing 80 cooler subdwarf B stars and is now releasing eye-opening results.
	www.findarticles.com /p/articles/mi_pfsf/is_200302/ai_1372017399 (567 words)

	Nearly-Naked Stars Boost the Pulse of Asteroseismology
		Figure1: A 5x5 arcminute CCD image of the prototype gravity-mode pulsating subdwarf B star, PG1716+426, and nearby comparison stars.
		The subdwarf B star pulsator is the brightest star in the northeast quadrant.
		The image was taken through an R filter at the University of Arizona Mt. Bigelow 1.6 m telescope and is one of hundreds used to measure the light curve of the star.
	www.innovations-report.com /html/reports/physics_astronomy/report-16369.html (576 words)

	Catalogue: III/137
		The Palomar-Green survey (Green et al., 1986ApJS...61..305G) detected over 900 hot subdwarfs, mostly in the North Galactic Cap and mostly previously unknown objects; the Kitt-Peak_Downes survey found another 60 near the Galactic Plane (Downes, 1986ApJS...61..569D).
		Hot subdwarfs in binary systems have been included but not planetary nebulae nuclei classified 'sd' since the latter have been catalogued elsewhere.
		Originally the classes 'sd B' and 'sd O' were recognized by broad Balmer line absorption and the early confluence of the Balmer series; B types were classified by weak or non-existent helium lines and O types by the presence of HeII 4686 or other HeII lines (see e.g.
	cdsweb.u-strasbg.fr /viz-bin/Cat?III/137 (1633 words)

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