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	SCYON: Paper abstracts
		We develop a simple model for the UV output from OB star clusters as a function of the cluster mass and age in order to interpret constraints provided by the observed luminosity functions.
		This implies that high mass star formation, cloud disruption due to OB stars and UV production is contributed by a large range of cluster masses with equal effects per logarithmic interval of cluster mass.
		We suggest that OB star formation in a cloud core region is terminated at the point that radiation pressure on the surrounding dust exceeds the self-gravity of the core star cluster and that this is what limits the maximum mass of standard OB star clusters.
	www.univie.ac.at /webda/scyon/Scoville.html (853 words)

	Cool Cosmos
		Infrared observations have led to the discovery of a large number of stars which are too cool to be detected by their visible light or are hidden behind obscuring dust.
		This star, which is 10 million times more radiant than our Sun, was discovered in the center of our galaxy where it was hidden from visible light telescopes by thick dust.
		The image to the left shows a "spiral" star which was discovered in the infrared.
	coolcosmos.ipac.caltech.edu /cosmic_classroom/ir_tutorial/stars.html (463 words)

	A Monte Carlo Simulation of OB Star Binary Evolution (Site not responding. Last check: 2007-10-20)
		We have developed a model that tests the idea that supernovas in massive binary systems can produce the high velocity populations of runaway OB stars, High Mass X-ray Binaries (HMXB's), Be stars and radio pulsars seen in the Galaxy.
		We find that the final mass transfer ratio affects the kinematics of the HMXB's, runaway OB and Be stars studied significantly.
		The magnitude of the kick velocity strongly affects the number of HMXB's and Be stars and also greatly alters the distribution of pulsar velocities produced.
	www.aas.org /publications/baas/v25n2/aas182/abshtml/S5601.html (235 words)

	pr-01-97.html
		One possibility is that some OB stars in an OB-association are ejected due to strong gravitational effects at the time of close encounters between the members of the group.
		For instance, an OB star with a mass of 25 times that of the Sun, will explode after only 10 million years, compared to an expected life-time of about 13,000 million years for the Sun (which is not an OB star and will not become a supernova).
		Blaauw suggested that when an OB star is bound to another OB star in a binary system (a `double star'), the supernova explosion of one of the stars (the heaviest of the two would explode first) results in the rapid acceleration (in astronomical terminology, a `kick') of the other one.
	www.eso.org /outreach/press-rel/pr-1997/pr-01-97.html (1791 words)

	Nebulae and Star Formation
		The proplyds which are closest to the hottest stars of the parent star cluster are seen as bright objects, while the object farthest from the hottest stars is seen as a dark object.
		The massive stars in A1 and A2 must have formed within the last 10,000 years, since their natal gas shrouds are not yet disrupted by the powerful radiation of the newly born stars.
		But once these luminous stars began to irradiate and destroy their surroundings, the clumps became visible when their less dense surroundings were eroded away, thus exposing them to the full brunt of the ultraviolet radiation and the expanding HII region.
	faculty.rmwc.edu /tmichalik/NebandStar.htm (6462 words)

	Vela X-1 light curve
		Because one can observe the Doppler shift in pulse arrival times from the pulsar simultaneously with the Doppler shift in spectral lines from the OB star, Vela X-1 is one of the few systems that can be treated as a double-lined spectroscopic variable.
		Currently, the mass of the OB star is measured to be 23 solar masses, while the pulsar weighs in at 1.77 solar masses, the highest measured value of a pulsar mass.
		Determining neutron star masses has important ramifications for the theoretical studies of equations of state of degenerate matter, an ongoing field of research which places upper bounds on the maximum stable neutron star mass.
	heasarc.gsfc.nasa.gov /docs/objects/binaries/velax1_lc.html (382 words)

	Nat' Academies Press, High-Energy Astrophysics: American and Soviet Perspectives/Proceedings from the U.S.-U.S.S.R. ... (Site not responding. Last check: 2007-10-20)
		These are formed in the collision of gas flowing out from the WR star with either the OB star's surface or the gas of the OB star's wind.
		Young mas- sive stars of the specnal type O and B are the second components of these systems.
		The velours of the matter outflow vower) is varying from zero on the OB star surface to v(°B) for r > r* (Barlow 1982), where r* Is approximately equal to (3-5)R, R is the OB star radius.
	www.nap.edu /openbook.php?record_id=1851&page=394 (2543 words)

	Star Clusters
		Since O and B stars are very bright their lives are short (up to about 20 million years), they do not have time to wander far away from their place of origin.
		Stars lighter than those of spectral types O and B are also formed from the same cloud of gas, and reside in the same region of space.
		OB associations are sparsely populated groupings of stars, typically between a few tens and a few hundreds of light-years across.
	universe-review.ca /F06-star-cluster.htm (2480 words)

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	www.starwalls.co.za (211 words)

	04.07.99 - Two battling blue stars create unique spiral dust cloud around distant star, UC Berkeley astronomers report
		Wolf-Rayet stars are typically three times the size and 25 times heavier than our sun, says William C. Danchi, a senior space fellow and principal investigator at UC Berkeley's Space Sciences Laboratory.
		The star is too far away - 4800 light years, or 28 million billion miles, from Earth, in the direction of the constellation Sagittarius - to obtain detail through conventional imaging techniques on any standard optical telescope, including the world's largest, the Keck.
		Wolf-Rayet stars are not only much bigger than the sun, they also are 100,000 times brighter, the same as the ratio of the brightness of the sun to the moon.
	www.berkeley.edu /news/media/releases/99legacy/4-7-1999b.html (1169 words)

	The initial mass function and star formation history of the Upper Scorpius OB association
		OB associations are large aggregates of hundreds to several thousand young stars.
		Since they are the dominant birthplaces for stars in our galaxy, a good knowledge of their properties and their formation history is essential for our understanding of the galactic structure and evolution.
		Unlike stellar clusters, which can be easily recognized on the sky, OB associations are often very inconspicuous: since they extend over huge areas in the sky (often several hundred square-degrees) its is very hard to "see" them, because most stars in the area actually are unrelated foreground or background stars.
	www.mpifr-bonn.mpg.de /staff/tpreibis/usco.html (735 words)

	Category:Stars - Wikipedia, the free encyclopedia
		The main article for this category is Stars.
		For star clusters, see the sub-category Star clusters.
		Timeline of white dwarfs, neutron stars, and supernovae
	en.wikipedia.org /wiki/Category:Stars (108 words)

	ONC
		Ten of the IRAS sources are associated with an OB star and 19 with a stellar cluster, although three OB stars are not identified with a cluster.
		Thus rich clusters around OB stars contribute substantially to the stellar population currently forming in the W3/W4/W5 region.
		Finally, we find that 4 of the 5 known embedded massive star forming sites in the W3 molecular cloud are found along the interface with the W4 HII region despite the fact that most of the molecular mass is contained in the interior regions of the cloud.
	www.astro.caltech.edu /~jmc/papers/w3 (707 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		The detection of a new runaway star, HIC 35707 (=HD 57682), whose motion is directed away from the derived center of expansion, supports this scenario and provides an independent age for the supernova remnant, assuming that the runaway star was the binary companion of the supernova.
		Finally, the latest-type IC 2602 stars are heavily Li depleted, with their Li content being as low as the lowest measured among the Pleiades.
		To appear in Astronomy and Astrophysics ABSTRACT: A refined value P=(4.4916+/-0.0002)d is derived for the rotation period of the Bp star HD 137509, from the simultaneous consideration of photometric data recorded in the Geneva system and of measurements of the mean longitudinal magnetic field and of the crossover.
	www.eso.org /gen-fac/pubs/pprints/science/science-pp-1997.txt (4377 words)

	Curriculum Vita
		Runaway OB stars are thought to be formed in two ways: cluster ejection of a member of an OB association through 3 and 4 body interactions (Leonard and Duncan 1988, 1990), or a supernova explosion in a massive binary system that leaves the surviving OB secondary with a recoil runaway velocity (Blaauw 1961).
		We were quite successful in generating a population of runaway OB stars that matched the observed Galactic population in both average velocity and in the fraction of O and B stars that are runaway.
		The effect of mass transfer evolution reduces the fraction of the system's mass that is ejected by the primary explosion which increases the fraction of surviving runaway OB stars with a compact companion.
	www.termanweb.net /cv.html (2274 words)

	MAST:FUSE:Stellar
		The second catalog, placed directly below the Galactic OB star catalog, is a table that serves data for 47 OB stars in the Large and Small Magellanic Clouds (see Walborn et al.
		Each group of stars is highlighted by a dark blue bar with a link "view montage" on the right.
		Clicking on the links on the right hand columns opposite the star name brings the reader to the gzipped fits file of the data (be sure to click on the mouse button combination that allows you to "save link as").
	archive.stsci.edu /prepds/atlasfuse (724 words)

	Star Types
		Looking at a star to determine temperature is not a very scientific way to go about things, so scientists turn to something called a spectrum.
		Every chemical element present in a star produces a line in the spectrum and by studying these lines scientists can determine a star's temperature and what the star is made of.
		These stars are almost identical to the state that they were born in.
	members.ncats.net /astro/reference/types.html (764 words)

	RobO's literature for: Neutron stars (Site not responding. Last check: 2007-10-20)
		Lett \\ It is generally considered that the neutron star cooling scenarios involving fast neutrino emission, from a kaon or pion condensate, quark matter, or the direct Urca process, require the presence of baryon pairing in the central core of the star to control the strong neutrino emission and produce surface temperatures compatible with observations.
		We study the four double neutron star systems found in the Galactic disk in terms of the orbital characteristics of their immediate progenitors and the natal kicks imparted to neutron stars.
		We identify the constraints imposed on the immediate progenitors of the observed double neutron stars and calculate the ranges within which their binary characteristics (orbital separations and masses of the exploding stars) are restricted.
	ad.usno.navy.mil /~olling/My_Lit_Dat/NeutronStars.html (1777 words)

	X-ray Binaries
		It often happens that this point is close to the companion's surface, so that some of the material in the star's outer edges (on the edge of the Roche lobe) finds itself no longer bound to the star.
		The Vela X-1 binary system is composed of a neutron star orbiting an OB supergiant (a class of giant star).
		By looking at the X-ray pulses in conjunction with the optical (visible light) lines from the OB star, we can make accurate estimates of the masses of both stars in the binary.
	www.airynothing.com /high_energy_tutorial/sources/binaries.html (662 words)

	13CO Observations of Cometary Cloud in IC 1396
		They also pointed out the possibility that this star formation was induced by the interaction with the strong UV field from the O6 star HD 206267, based on the fact that the dense head core of the cometary globule, covered by the ionization front, faced toward this O6 star.
		This agreement and the fact that the densest part of the globule is facing toward the exciting star may be due to the interaction between the molecular cloud and the UV radiation or stellar wind from the exciting star(s) of IC 1396.
		One is that within a single globule, star formation progresses continuously according to the movement of the densest part of the compressed gas along the symmetry axis from the exciting-star side to the tail side.
	ecf.hq.eso.org /~ralbrech/sepdec97apjl/5154.html (3872 words)

	Colliding-wind binary stars
		A survey of X-ray emission from WR stars [2] confirmed that binaries were stronger X-ray sources than single WR stars - and the brightest of these was WR140.
		The northern radio source is non-thermal emission from the region where the WN8 stellar wind collides with that of the OB star.
		This occurs between the two stars and is closer to the OB star because it has a weaker stellar wind than the WN8 star.
	www.roe.ac.uk /~pmw/Wr140cwb.htm (343 words)

	Wolf-Rayet Stars
		Their spectra indicate that the stars are embedded in luminous and turbulent shells of ejecta flowing outwards at speeds comparable to the expansion velocities of novae (Cherepashchuk 1992, p.
		The progenitor stars might be red supergiants, luminous blue variables or possibly binary stars which have lost their outer envelope to a close companion through Roche-lobe overflow.
		The stars showing broadened emission lines are supposed to occupy the left side of the W-R ‘funnel’ (marked B in fig.
	www.peripatus.gen.nz /Astronomy/WolRaySta.html (3355 words)

	Neutron Star X-ray binaries
		The spectral features of the late type star are usually outshone by the reprocessing at optical wavelengths of the X-ray flux intercepted by the accretion disc and the star.
		G) of young neutron stars confines the infalling plasma to the polar caps, thereby increasing dramatically the accretion rate per unit area (compared to weakly magnetic neutron stars) and giving rise to steady (as opposed to flash-like) thermonuclear burning in the accreting material (Fujimoto, Hanawa and Miyaji 1981; Hanawa and Fujimoto 1984).
		The identification of the optical counterparts of bright transients, in crowded and often heavily absorbed regions of the galactic plane, is often made easier by the optical flux increase associated with the outburst.
	www.mporzio.astro.it /~gianluca/phdthesis/node11.html (4115 words)

	wr104 (Site not responding. Last check: 2007-10-20)
		There must be another star lurking in the middle, making this a binary star system, and although the companion is not quite a twin brother to the Wolf-Rayet, it is nevertheless a luminous blue OB star with a strong stellar wind of its own.
		When the stellar wind from the OB companion meets the wind from the Wolf-Rayet star, a shock front forms which compresses the material from the stellar winds.
		Despite this, we have seen this star also has a spiral outflow tail, and we have made a movie showing its motion, which is displayed to the right.
	www.astro.lsa.umich.edu /~monnier/WR104/wr104.htm (1481 words)

	NASA's Solar System Exploration: News & Events: 12.13.04: Star Gazing
		On Dec. 8, the MESSENGER spacecraft spent three hours looking for a star, specifically a Leo (a 1.35-magnitude OB class star) to confirm that the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) instrument was functioning as designed.
		These observations were part of the instrument's first post-launch calibration and maintenance operation since the commissioning checkout early in the mission that certified it had survived the intensity of launch.
		The second test was a 48-hour maintenance check that included prompting the instrument shutters, slits and grating drive to open and close to verify they were operational and that the detectors will have an unfettered view when their science mission begins.
	solarsystem.nasa.gov /news/display.cfm?News_ID=10195 (583 words)

	Can Field OB Stars Ionize the WIM?
		However, a careful census of the field star population is required.
		The concentration of OB field stars in the general areas near HII regions could well give rise to similar spectral characteristics for the WIM as the leaking HII region model.
		Some of the far-UV light in regions of WIM could be due to light scattered from OB stars inside HII regions.
	www.atnf.csiro.au /pasa/15_1/walterbos/paper/node4.html (412 words)

	[No title]
		Each target should be observed during 3 hours in H band in the 8"x8" mode (0.25" arcsec pixel scale).
		For each object the observations have been splitted in 3 OBs of 1 hour on target each.
		Characteristics of the OBs are the following: DIT NDIT NumberOfABseq 900s 1 2 Total exposure time is 900x2x2=3600s Since the sources are relatively small, we have chosen to use a dithering pattern that always keeps the source in the field (no pure sky frames).
	www.eso.org /science/vltsv/sinfonisv/README_Kstarbursts.txt (522 words)

	Wind-fed accretion
		In many X-ray binaries the mass-losing star does not fill its Roche lobe and the compact object accretes from the wind of the star.
		This is called wind-fed accretion and occurs in systems where the donor star is an OB-star.
		-axis is directed from the donor star to the accretor.
	www.astro.su.se /Xgamma/sara/node5.html (791 words)

	LARGE SCALE DISTRIBUTION AND PHYSICAL PROPERTIES OF MOLECULAR CLOUDS AND REGIONS OF MASSIVE STAR FORMATION IN THE MILKY ...
		Regions of OB star formation in the galactic disk are detected as IRAS point-like sources with FIR colors characteristic of UC HII regions.
		Our intention is to give the best rendition of the large scale distribution of molecular clouds and regions of OB star formation in the galactic disk.
		An important difficulty to remove is the two-fold distance ambiguity within the solar circle: we will use for this purpose observations of HI in absorption from the new Australia Telescope Southern Survey.
	www.conicyt.cl /bases/fondecyt/proyectos/01/2001/1010431.html (591 words)

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