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Topic: Stellar classification

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List of mnemonics for star classification

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	Stellar - Space Wiki - a Wikia wiki
		Stellar aberration is an astronomical phenomenon defined as an apparent motion of the heavenly bodies due to a combination of the motion of the Earth and the finite velocity of light.
		Stellar astronomy is the study of stars and the phenomena exhibited by the various forms/developmental stages of stars.
		Stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequenly refined in terms of other characteristics.
	space.wikia.com /wiki/Stellar (435 words)

	Stellar classification at AllExperts (Site not responding. Last check: 2007-10-26)
		In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics.
		Stellar spectroscopy offers a way to classify stars according to their absorption lines; particular absorption lines can be observed only for a certain range of temperatures because only in that range are the involved atomic energy levels populated.
		This classification is based on spectral lines sensitive to stellar surface gravity which is related to luminosity, as opposed to the Harvard classification which is based on surface temperature.
	en.allexperts.com /e/s/st/stellar_classification.htm (2592 words)

	News: Stellar Classification Systems Using Neuroshell 2 (Site not responding. Last check: 2007-10-26)
		The problem of stellar classification is an amazingly good fit for the application of ANNs.
		The second interesting part of the story (from the point of view of the applicability of ANNs to the problem) was the development of the modern stellar classification system in the 1940s by Morgan and Keenan.
		Classification of large numbers of normal stars in certain areas of the sky let us understand something of the local structure and, perhaps, dynamics of our Milky Way Galaxy.
	www.wardsystems.com /news.asp?13 (766 words)

	Stellar - Wikipedia, the free encyclopedia
		A stellar fl hole is a fl hole formed by the collapse of a massive star at the end of its lifetime.
		Stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics.
		A stellar engine is a hypothetical propulsion device that employs a significant part of a star's radiation to change the star's velocity (literally: an engine for a star).
	en.wikipedia.org /wiki/Stellar (531 words)

	World Almanac for Kids
		The photographic study of stellar spectra was initiated in 1885 by the American astronomer Edward Charles Pickering at the Harvard College Observatory and carried out principally by the American astronomer Annie J. Cannon.
		This research led to the important discovery that stellar spectra can be arranged in a continuous sequence, based on the relative intensity of certain absorption lines occurring in the spectra.
		Theories of stellar evolution are based primarily on clues obtained from studies of the stellar spectra related to luminosity.
	www.worldalmanacforkids.com /explore/space/star.html (3216 words)

	ScienceDaily: Scientists Track Collision Of Powerful Stellar Winds
		Red giant -- A red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars.
		Stellar classification -- In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral...
		Stellar evolution -- In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat.
	www.sciencedaily.com /releases/2005/04/050413095400.htm (1941 words)

	The Classification of Stellar Spectra (Site not responding. Last check: 2007-10-26)
		Important lines are the hydrogen Balmer lines, lines of neutral and singly ionized helium, iron lines, the H and K doublet of ionized calcium at 396.8 and 393.3 nm, the G band due to the CH molecule, the 422.7 nm neutral calcium line, several metal lines around 431 nm, and the lines of titanium oxide.
		Ordered from highest temperature to lowest, the seven main stellar types are O, B, A, F, G, K, and M. Astronomers use one of several mnemonics to remember the order of the classification scheme.
		This may nicely explain several stellar types which seem analogous with K and M stars temperature-wise, but show some other spectral features as if their outer atmospheres had been enriched with heavier element.
	zuserver2.star.ucl.ac.uk /~pac/spectral_classification.html (1913 words)

	Efficiency and Completeness of the Survey
		Of the 219 candidates, 97 were classified as stellar on both plates, 29 as stellar on the E plate only, and 93 as stellar on the blue plate only.
		The reliability of the APM classifier is magnitude dependent: all 11 QSOs which are stellar on the O plate only are 18th magnitude or brighter on the O plate.
		Seventy-four fainter candidates are included in the initial sample of 219 because of a stellar classification from only the O plate; all but 6 of these have O-E colors redder than 2.0.
	sundog.stsci.edu /first/fbqs/node4.html (788 words)

	Galaxies and the Universe - Galaxy Classification
		Unfortunately, this nomenclature is opposite to that of the dominant stellar population in these types, and to the early-late nomenclature in the Yerkes classification.
		This classification uses a form factor E,S,B, or D (for symmetric but non-E or S systems) and inclination class 1-7 (7 most elongated) plus a spectroscopic type corresponding to the nearest stellar equivalent to the spectroscopic appearance of a typical galaxy of similar morphological structure (confused yet?).
		Classifications of this kind, based on light concentration, have received renewed interest in the context of high-redshift galaxies, and with the recognition that they can be made robust even for poorly resolved systems by appropriate modelling.
	www.astr.ua.edu /keel/galaxies/classify.html (2853 words)

	eSky: Spectral Classification
		The classification of stars according to their spectra; each major spectral classification is given a letter, with additional numbers providing further subdivisions.
		A star's full spectral classification often also includes a 'luminosity class', a Roman numeral from I to VII indicating the star's luminosity, which correlates with its mass.
		For example, the full spectral classification for Achernar is B3Vp, with 'p' indicating that it has a peculiar spectrum, while Castor in Gemini is classified as A2Vm, with 'm' demonstrating that the spectrum contains strong metal lines, and so on.
	www.glyphweb.com /esky/concepts/spectralclassification.html (1065 words)

	[2.0] Touring The Sun & The Stars (Site not responding. Last check: 2007-10-26)
		This means that the coordinates of stellar objects in terms of declination and right ascension vary over time, and properly declination and right ascension have to be given along with a date.
		Along with stellar composition, radial velocity, and rotation rate, spectroscopy can be used to determine the size of orbits in binary systems, which allows a determination of stellar mass.
		One of Pickering's assistants, Wilhelmina Fleming, gave the stellar classes a nice neat alphabetical sequence early in the group's stellar classification effort, but by the end of the work, they had been forced to drop some classes and shuffle others around.
	www.vectorsite.net /tastga2.html (4163 words)

	Kepler Mission > Goals and Objectives (Site not responding. Last check: 2007-10-26)
		The planet's semi-major axis is derived from the measured period and stellar mass, using Kepler's Third Law.
		As above, the semi-major axis is derived from the orbital period and the stellar mass.
		Stellar age and mass is determined from Kepler p-mode measurements.
	www.ulo.ucl.ac.uk /~diploma/year_one/NASA_Kepler/goals.html (578 words)

	Recent progress in quantitative spectral classification from stellar spectral libraries (Site not responding. Last check: 2007-10-26)
		Spectral classification based on low resolution spectra is a powerful tool in astronomy providing the main physical parameters (effective temperatures, absolute magnitudes, metallicities) for large samples of stars, the results are applied to galactic studies.
		The majority of the available classification data have been obtained visually in the MK system on photographic emulsions (wavelength range 3900-4900 A, about 2A resolution), many thousands of stars have been classified by now.
		Some appropriate spectral libraries have been created by different authors with the aim of using the data in modelling stellar atmospheres, spectral classification and in spectral synthesis of the stellar populations of galaxies.
	www.asu.cas.cz /~kubat/AIB/malyuto.html (257 words)

	Spectral Classification of Stars
		The resulting classification was a key step in elucidating the underlying physics that produces stellar spectra.
		Astronomers reordered the classification sequence such that the hottest stars came first, but they retained the letters originally assigned to each star based on their Balmer line strengths.
		Rewrite the classification sequence you found in Table 4 to include L, M and T stars.
	www.astro.washington.edu /labs/clearinghouse/labs/word_documents/classifying_stars.html (2164 words)

	stellar - Search Results - MSN Encarta
		Magnitude, term used in astronomy to designate the brightness, real or apparent, of a celestial object.
		The photographic study of stellar spectra was initiated in 1885 by the American astronomer Edward Charles Pickering at the Harvard College...
		The extended corona, or outer atmosphere, of the Sun has a temperature of 1 million K and has been well studied by X-ray telescopes (both imaging and...
	uk.encarta.msn.com /stellar.html (141 words)

	Stellar classification
		Class W is subdivided into subclasses WN and WC according to the dominance of nitrogen or carbon in their spectra (and outer layers).
		Class R and N stars are carbon stars (red giants thought to reach the end of their life) which run parallel to the normal classification system from roughly mid G to late M. These have more recently been remapped into a unified carbon classifier C, with N0 starting at roughly C6.
		For stars cool enough for CO to form that molecule tends to "eat up" all of whichever element is less abundant, resulting in "leftover oxygen" on the normal main sequence, "leftover carbon" on the C sequence, and "leftover nothing" on the S sequence.
	www.blogmyway.com /artiframe/document.php?id=1213 (2236 words)

	PointedEars' LCARS: UFPDB: Stellar Classification System
		A classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics.
		The most popular stellar classification system on Terra, thus becoming Earth Starfleet standard (2065 to 2161 CE) and Federation standard (since 2161 CE) later, is described below.
		It was developed by Annie Jump Cannon of the Harvard College Observatory from 1915 to 1924 CE while she and her colleagues were ordering 225,300 stars into stellar spectra of types O, B, A, F, G, K and M into what was published as the Henry Draper Catalogue shortly after.
	pointedears.de /ufpdb/celestia/?file=stellarcl (134 words)

	IMSA Astrophysics: Distance Ladder
		In the course of the Harvard classification study, some of the old spectral types were consolidated together, and the types were re-arranged to reflect a steady change in the strengths of representative spectral lines.
		The early spectral classification system was based on the appearance of the spectra, but the physical reason for these differences in spectra were not understood until the 1930’s and 1940’s.
		The spectral classification system used today is a refinement called the MK system, introduced in the 1940’s and 1950’s by W. Morgan and P.C. Keenan at Yerkes Observatory to take account of the fact that stars at the same temperature can have different sizes.
	staff.imsa.edu /science/astro/astrometry/stellarclass_a.html (1199 words)

	Kepler Mission > Stellar Variability (Site not responding. Last check: 2007-10-26)
		The shallow slope beyond this region is attributed to the combined effects of gravity oscillations and the non-solar noise injected into the data set.
		The differences in the high frequency levels of the measurement noise are due to the varying amounts of shot noise at the different stellar magnitudes represented.
		Hence, convection depends only on stellar mass while magnetic processes are highly sensitive to a star's rotation rate.
	kepler.nasa.gov /sci/basis/variability.html (894 words)

	Galaxy Classification Lab - Astro 113 - Matthew A. Bershady
		This hoped-for insight is prompted most directly by how the spectral classification of stars provided astronomers with the impetus and framework to comprehend the physics that make stars shine.
		There have been many subsequent variants, but largely the classification has been based on subjective, qualitative assessments of the distribution of optical light -- what is often referred to as 'galaxy morphology.' There are many problems with the approach, yet it has remained paramount for over 70 years.
		In this context, a 'meaningful' classification is one where there were reasonably close counterparts in the reference sequence.
	www.astro.wisc.edu /~mab/education/astro113/galclass_lab.html (2607 words)

	[No title] (Site not responding. Last check: 2007-10-26)
		The contributions range from spectral classification of ultra cool dwarfs through infrared classification of A-M type stars, to using the data anticipated from the GAIA spacecraft to determine the basic physical parameters of stars.
		A first attempt at a near-infrared classification scheme for T dwarfs is made, based on the strengths of CH4 and H2O bands and the shapes of the 1.25, 1.6, and 2.1 micron flux peaks.
		Although ISO SWS data cover from 2.35 micron to 45.2 micron, the classification scheme will be restricted to the shorter wavelength region because of the quick drops of the stellar brightness, the lack of molecular and atomic line lists, and the unknown circumstellar contribution in the longer wavelength region.
	stellar.phys.appstate.edu /ssn/ssn31.txt (1434 words)

	Data Mining in Astrophysics
		Stellar parameters from very low resolution spectra and medium band filters.
		Spectral analysis of stellar light curves by means of neural networks.
		Automated classification of stellar spectra - part one - initial results with artificial neural networks.
	www.cs.queensu.ca /home/mcconell/DMAstroStars.html (552 words)

	Star classification - Scientia Astrophysical Organization
		This is called “Morgan-Keenan spectral classification”, even though its form was already by Annie Cannon, also based on the work of other astronomers from the Harvard College Observatory.
		While these descriptions of stellar colors are traditional in astronomy, they really describe the light as we see them from Earth, after it has been scattered by the atmosphere.
		The Sun is not in fact a yellow star, but has the color temperature of a body of 5780 K, that is a white with no trace of yellow which is sometimes used as a definition for standard white.
	www.astrophysical.org /starclassification.php (882 words)

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