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Topic: Dwarf elliptical galaxies

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 dwarf elliptical galaxy   (Site not responding. Last check: 2007-11-06)
A dim, low-surface-brightness, gas-poor dwarf galaxy, large numbers of which are found in clusters of galaxies, especially in the vicinity of large galaxies.
Despite their name, dwarf ellipticals are not really fainter versions of true elliptical galaxies, but are structurally distinct.
Dwarf ellipticals are of special interest because it is possible that they are very similar to the fragments from which larger galaxies formed.
www.daviddarling.info /encyclopedia/D/dwarf_elliptical.html   (247 words)

 book near-field cosmology with dwarf elliptical galaxies, essential astronomy, cosmology, lavoisier publishers
Present-day dwarf galaxies, the easily studied survivors of the primordial galaxy population, are important targets for research in the quest to provide local benchmarks for cosmological studies, in particular theories of structure formation.
The interpretation of the faint blue galaxy excess, the mismatch of the observed dwarf galaxy numbers with popular cosmological model predictions, and the puzzling diversity of star-formation histories among Local Group dwarf elliptical galaxies, are amongst the topical questions covered.
Dwarf galaxy specialists and cosmologists map out strategies and outline a framework for progress on important issues related to near-field cosmology with dwarf elliptical galaxies.
www.lavoisier.fr /notice/gb412190.html   (202 words)

 galaxy galaxies stars
Galaxies are a massive ensemble of hundreds of millions of stars,all gravitationally intreacting,and orbiting about a common center.All the stars and planets that we see visionally from earth belong to the earth's galaxy,the Milky Way.
The galaxy M100 (100th object in the Messier Catalog of non-stellar objects) is one of the brightest members of the Virgo Cluster of galaxies.
Though the galaxy is estimated to be tens of millions of light-years away, Hubble reveals the sort of detail only seen previously (with ground based telescopes) in neighboring galaxies that are ten times closer.
www.geocities.com /CapeCanaveral/Hall/1491/galaxy.html   (809 words)

 Dwarf Elliptical Galaxies in the Coma Cluster Core   (Site not responding. Last check: 2007-11-06)
The dwarf elliptical (dE) galaxies are confined to a well-defined sequence in the color range given by 0.7 \le (B-R) \le 1.9 mag; within this interval and complete to R = 22.5 mag, there are 2535 dE candidates in the cluster core, and 694 objects on the associated control field (2.57\times less area).
The composite luminosity function for Coma galaxies was modeled as the sum of a log-normal distribution for the giant galaxies and a Schechter function for the dE galaxies.
Decomposing the galaxy luminosity function in this manner, I found that the early-type dwarf-to-giant ratio (EDGR) for the Coma cluster core is identical with that of the Virgo cluster.
www.aas.org /publications/baas/v27n4/aas187/S063003.html   (364 words)

 Chapter 24: The Local Galaxies
Dwarf elliptical galaxies appear to be the most common type of galaxy, and most of them may be satellite attendants to larger galaxies.
However, remember that the classification of galaxies is based on the roughly 10% of the mass of the galaxy that emits light.
Irregular galaxies contain almost pure Population I. Spiral galaxies contain a mixture of the two populations, with Population I star-forming regions concentrated in the spiral arms and Population II stars in the central bulges.
mywebpage.netscape.com /GWBlaylock/Astr1010/Chapter24.html   (1165 words)

 Dwarf Spheroidals   (Site not responding. Last check: 2007-11-06)
The term dwarf spheroidal (dSph) is applied to the twelve low luminosity dwarf elliptical galaxies that are companions to the Milky Way and to the similar systems that are companions to M31 (The Andromeda Galaxy).
Since the individual stars in dSph galaxies can be resolved, their study will contribute to the understanding of the origin and evolution of dwarf galaxies in general.
The existence of this latter population is revealed by, for example, the presence of carbon stars on the AGB with luminosities above that of the first giant branch tip, and by the presence of main sequence stars whose luminosities exceed that of the turnoff for an old population.
www.astro.uu.se /~ns/review.html   (434 words)

 Elliptical Galaxies   (Site not responding. Last check: 2007-11-06)
Elliptical galaxies constitute approximately 10% of observed galaxies.
Some other examples of elliptical galaxies include M32, which is an E2 dwarf elliptical near the Andromeda Galaxy, and the E6 elliptical galaxy M110, another satellite of the Andromeda Galaxy.
Elliptical galaxies exhibit far less evidence for young stars, gas, or dust than do spiral galaxies, and have larger random motion of stars than in spiral galaxies where the motion is a more ordered rotation.
csep10.phys.utk.edu /astr162/lect/galaxies/elliptical.html   (257 words)

 dwarf galaxy
Dwarf irregular galaxies tend to contain a lot of gas and usually show strong signs of ongoing star formation, whereas dwarf elliptical galaxies (of which dwarf spheroidal galaxies are a subcategory) tend to be gas-poor, lower in mass and luminosity, and quiescent.
Dwarf galaxies are the commonest variety in the Local Group and, almost certainly, in the Universe as a whole.
It has been speculated that heavy elements escaping from dwarf galaxies in the early universe may have played a dominant role in enriching the intergalactic gas from which other galaxies form.
www.daviddarling.info /encyclopedia/D/dwarfgal.html   (288 words)

 Elliptical Galaxies   (Site not responding. Last check: 2007-11-06)
Elliptical galaxies are also named because of their shapes.
Elliptical galaxies range from circular (remember, a circle is an ellipse!) to long, narrow, and cigar-shaped.
Elliptical galaxies are denoted by the letter E. They are also given a number from 0 to 7.
cas.sdss.org /dr4/en/proj/basic/galaxies/ellipticals.asp   (149 words)

 Dwarf elliptical galaxy
"Dwarf elliptical galaxies, such as NGC 185, pose a complex and little understood problem that might even be said to have a 'social' guise among astrophysicists," explains Aparicio, who heads the IAC's Stellar Populations group, which has carried out the study.
This is because these galaxies were directly involved in the construction of one of the key paradigms of the astrophysics of this century: the concept of stellar populations, introduced by Walter Baade (1893-1960), an astronomer at the Carnegie Institute in Pasadena (California, USA).
The observation of recent star formation in the galaxy NGC 187 contradicts the scheme established in the 1940s by the distinguished astronomer Walter Baade according to which dwarf elliptical galaxies are populated only by old stars.
www.xs4all.nl /~carlkop/dwarfell.html   (831 words)

 Curious About Astronomy? Galaxies
Galaxies with prominent bulges and pronounced spiral arms are classified as "Sb" (M31, M81) or "SBb" (M95, NGC 4725).
Though the origin of lenticular galaxies is still debated the most plausible explanation to date is that the gas and stars that would reside in the galaxy disk have been stripped by interactions with the hot gas in clusters and groups of galaxies.
This irregular class of galaxies is a miscellaneous class, comprising small galaxies with no identifiable form like the Magellanic clouds (the Large Magellanic Cloud and Small Magellanic Cloud are two satellite galaxies of the Milky Way) and "peculiar" galaxies that appear to be in disarray like NGC 1313.
curious.astro.cornell.edu /galaxies.php   (1813 words)

 Durrell - Intracluster Stars   (Site not responding. Last check: 2007-11-06)
The name `dwarf elliptical' is actually a bit of a misnomer, as this class of LSB object is not really a fainter version of a true elliptical galaxy, but structurally different.
These small galaxies are of interest to astronomers as it is possible that they (or really, their progenitors) are the `fragments' from which the larger galaxies formed (in the `bottom-up'scenario of galaxy formation).
Although these are the smallest galaxies known, they often have very different star formation histories -- a surprising result as these objects were not expected to be able to hold onto any of the gas needed for stars to form.
cc.ysu.edu /~prdurrel/Research/DwarfGalaxies/DwarfGalaxies.html   (346 words)

Dwarf galaxies may not be as impressive in appearance as their larger brethren, but they are at least as interesting from a scientific point of view.
Dwarf galaxies are present in all major clusters of galaxies and dominate by numbers in the universe.
The galaxies that are found to have smooth light distributions are of special interest, because it is then possible to measure their approximate distance by means of the so-called Surface Brightness Fluctuation method [2].
www.eso.org /outreach/press-rel/pr-2000/pr-12-00.html   (1111 words)

 The Local Group   (Site not responding. Last check: 2007-11-06)
The vast clouds of cool hydrogen gas which envelop galaxies are not visible in optical, ultraviolet or infrared images; but by superimposing a radio map (shown in blue) of the 21-centimeter radiation of hydrogen on an optical image of M33, the hidden becomes visible.
If such stars did not exist, the galaxies would be much fainter, and in so-called elliptical galaxies stars exist in large numbers, but no hot, bright stars have recently formed, making such galaxies far fainter and less impressive than their masses would warrant.
Until recently, it was suspected that such metal-poor galaxies were very old, but because of their small size, it seemed possible that they might have formed so recently that their stars simply hadn't had a chance to develop heavy metals yet.
cseligman.com /text/galaxies/local.htm   (1267 words)

The Sagittarius dwarf galaxy represents a subclass of dwarfs known as nucleated dwarf elliptical galaxies.
Curiously the origin of nucleated dwarf elliptical galaxies is believed to have occurred by one of two mechanisms; either the decay of the orbit of a pre-existing globular cluster or the in situ formation of a giant cluster.
The dwarf galaxy is so large and extended that it represents a barely perceptible increased stellar concentration from the sky foreground.
www.robgendlerastropics.com /Sagdwarftext.html   (820 words)

 Elliptical Galaxies
Elliptical galaxies are spheroidal concentrations of billions of stars that resemble Globular Clusters on a grand scale.
Elliptical galaxies span a very wide range of sizes and luminosities, from giant Ellipticals hundreds of thousands of light years across and nearly a trillion times brighter than the sun, to dwarf Ellipticals just a bit brighter than the average globular cluster.
M 86 is a normal Elliptical galaxy in the Virgo cluster of galaxies.
docs.kde.org /stable/en/kdeedu/kstars/ai-ellipgal.html   (533 words)

 Dwarf Elliptical Galaxies   (Site not responding. Last check: 2007-11-06)
New observations of 16 dwarf elliptical galaxies in the Virgo Cluster indicate that at least seven dEs have significant velocity gradients along their optical major axis, with typical rotation amplitudes of 20-30 km/s.
These observations reaffirm the possibility that some cluster dwarf elliptical galaxies may be formed when the neutral gaseous medium is stripped from dwarf irregular galaxies in the cluster environment.
We hypothesize that several different mechanisms are involved in the creation of the overall population of dE galaxies, and that stripping of infalling dIs may be the dominant process in the creation of dEs in clusters like Virgo.
www.astro.indiana.edu /~vanzee/html/dE.html   (242 words)

Galaxies are large systems of stars and interstellar matter, typically containing several million to some trillion stars, of masses between several million and several trillion times that of our Sun, of an extension of a few thousands to several 100,000s light years, typically separated by millions of light years distance.
The most massive galaxies are giants which are a million times more massive than the lightest: Their mass range is from at most some million times that of our Sun in case of the smallest dwarfs, to several trillion solar masses in case of giants like M87 or M77.
Our Milky Way Galaxy, a spiral galaxy, is among the massive and big galaxies with at least 250 billion solar masses (there are hints that the total mass may even be as large as 750 billion to 1 trillion times that of the Sun) and a disk diameter of 100,000 light years.
www.seds.org /messier/galaxy.html   (1771 words)

 Normal Galaxies and Hubble’s Law
Elliptical galaxies are designated with the letter “E.”  These are divided into eight subcategories, E0, E1, E2, E3, E4, E5, E6, and E7.
Just as we can use the motion of objects within galaxies to determine that they must contain 3-10x more material than we can see (in the form of dark matter), we can use the motions of galaxies within galaxy clusters to determine that the clusters contain even more dark matter.
Galaxies are not homogeneously distributed on small scales.
www.physics.rutgers.edu /~abragg/110/lecture21.html   (1533 words)

 UF ASTRONOMERS: UNIVERSE SLIGHTLY SIMPLER THAN EXPECTED   (Site not responding. Last check: 2007-11-06)
Galaxies, the building blocks of the visible universe, are enormous systems of stars bound together by gravity and scattered throughout space.
This scouring phenomenon had tended to dim the centers of giant elliptical galaxies, which ran counter to the trend that bigger galaxies tend to have brighter centers.
Building on recent revelations showing a strong connection between the mass of the central fl holes and the properties of their host galaxies, Graham and his colleagues introduced a new mathematical model that simultaneously describes the distribution of stars in the inner and outer parts of the galaxy.
www.napa.ufl.edu /2003news/galaxies.htm   (742 words)

 Elliptical Galaxies   (Site not responding. Last check: 2007-11-06)
Elliptical galaxies are a cornerstone in our understanding of the galaxy formation process in a cosmological frame.
According to the currently most popular models, elliptical galaxies are the outcome of (multiple) merging of already formed units, as a natural result of the hierarchical models which successfully account for the large scale structure observed in the local universe.
Unfortunately, the vast majority of ellipticals cannot be resolved into single stars, and the age-dating of their stellar content relies on studies of the their integrated light.
www.bo.astro.it /report99/node36.html   (387 words)

 Independent Florida Alligator - NEWS   (Site not responding. Last check: 2007-11-06)
The duo published their findings in this month's edition of The Astronomical Journal, saying that the commonly found "dwarf elliptical" galaxies and the much larger "giant elliptical" galaxies should no longer be categorized differently by the research community.
Galaxies are giant groups of stars scattered through space that are held together by gravity.
Graham said the difference in size of the two types of galaxies is likely just a result of the initial size of the gas cloud from which the given galaxy is believed to have originated.
www.alligator.org /edit/news/issues/stories/030617universe.html   (271 words)

 Beginners – galaxies
Hubble studied galaxies for a very long time, and after seeing many, many galaxies, he realized that he could put them into groups based on their shape: spirals, ellipticals, or irregulars (fig.
It is important to realise that this diagram, sometimes referred to as the "tuning fork diagram of galaxies" is not an indication of the evolution of galaxies.
Spiral galaxies are complex objects and have several components: a disk, a bulge, and a halo.
www.fortunecity.com /meltingpot/alameda/1194/HTMLobj-93/page4.html   (750 words)

 Dwarf Elliptical Galaxies   (Site not responding. Last check: 2007-11-06)
Stellar Populations of Dwarf Elliptical Galaxies: UBVRI Photometry of Dwarf Elliptical Galaxies in the Virgo Cluster
We present UBVRI surface photometry for 16 dwarf elliptical galaxies in the Virgo Cluster with previously measured kinematic properties.
We recover the well known color-magnitude relation for cluster galaxies, but find no significant difference in dominant stellar population between rotating and non-rotating dwarf elliptical galaxies; the average age of the dominant stellar population is 5-7 Gyr in all 16 galaxies in this sample.
www.astro.indiana.edu /~vanzee/html/dE_UBVRI.html   (290 words)

 Spectral observations of Dwarf Elliptical Galaxies   (Site not responding. Last check: 2007-11-06)
I have been involved in spectral observations of Dwarf Elliptical Galaxies using the Double Spectrograph at the Palomar Observatory, California.
The September 2001 run was spent looking for the signature of rotation in three of the dwarf elliptical companions of the Andromeda galaxy.
Dwarf elliptical galaxies (like their giant counterparts) are not supposed to rotate according to accepted knowledge, but in March 2001 (in the first observing run for this project) Liese and Martha found evidence that at least some in the Virgo Cluster do.
astrosun.tn.cornell.edu /~masters/dwarfEs.html   (332 words)

 Dwarf elliptical galaxy - Wikipedia, the free encyclopedia
Dwarf elliptical galaxies are elliptical galaxies that are much smaller than others, classified as dE.
A subtype of dwarf ellipticals is called a dwarf spheroidal galaxy.
There is evidence that when our galaxy (the Milky Way) collides in 3-4 billion years with the Andromeda Galaxy, the newly combined galaxy will become a elliptical galaxy.
en.wikipedia.org /wiki/Dwarf_elliptical_galaxy   (227 words)

 Universe Slightly Simpler Than Expected
University of Florida researchers have concluded that two forms of galaxies thought to be different are instead versions of the same type, a finding that will make it easier to understand how galaxies form.
The resulting dimming of the galaxy center was one reason they were thought to be a different than the type classified as dwarf elliptical.
The resulting sample revealed that the structural properties of the galaxies varied continuously between the allegedly different dwarf and giant galaxy classes -- in other words, these two types were just relatively extreme versions of the same object.
www.spacedaily.com /news/cosmology-03u.html   (891 words)

Galaxies are also known by their "name", with the two most popular naming schemes being those of the Messier (M) and the New General Catalog (NGC).
In the infrared light, M82 is the brightest galaxy in the sky.
Galaxies that are relatively close to the Milky Way do not necessarily recede from us; some are actually approaching us because of gravitational attraction.
www.physics.fsu.edu /users/Dobrosavljevic/Galaxies.htm   (849 words)

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