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Topic: Hubble sequence


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  Hubble sequence - Wikipedia, the free encyclopedia
The Hubble sequence is a classification of galaxy types developed by Edwin Hubble in 1936.
It is also called the tuning-fork diagram as a result of the shape of its graphical representation.
Hubble based his classification on photographs of the galaxies through the telescopes of the time.
en.wikipedia.org /wiki/Hubble_sequence   (406 words)

  
 EDWIN HUBBLE 1889-1953 By Allan Sandage (1989, JRASC Vol. 83, No.6)   (Site not responding. Last check: 2007-10-21)
There is Hubble's zone of avoidance, the Hubble galaxy type, the Hubble sequence, the Hubble luminosity law for reflection nebulae, the Hubble luminosity profile for E galaxies, the Hubble constant, the Hubble time, the Hubble diagram, the Hubble redshift-distance relation, the Hubble radius for the universe, and now the Hubble Space Telescope.
As with Hubble's Cepheid paper 5 years before, and his space distribution paper to come 5 years in the future, Hubble's (1929b) discovery paper of the expansion was written so convincingly that it was believed almost immediately.
In perhaps the most important paper on the series, Hubble and Humason (1931) showed beyond doubt (a) the existence of the effect, (b) that it was linear with distance, and (c) that the brightest members of clusters are predominantly E galaxies (a major discovery related to galaxy and cluster formation).
antwrp.gsfc.nasa.gov /diamond_jubilee/1996/sandage_hubble.html   (4767 words)

  
 Galaxy - Wikipedia, the free encyclopedia
Since the Hubble sequence is entirely based upon visual morphological type, it may miss certain important characteristics of galaxies such as star formation rate (in starburst galaxies) or activity in the core (in active galaxies).
In 1936, Hubble produced a classification system for galaxies that is used to this day, the Hubble sequence.
The Hubble Deep Field, an extremely long exposure of a relatively empty part of the sky, provided evidence that there are about 125 billion galaxies in the universe.
en.wikipedia.org /wiki/Galaxy   (2439 words)

  
 Burned-Out Stars Give Reading On Age Of The Universe
Because earlier Hubble observations show that the first stars formed less than 1 billion years after the universe’s birth in the Big Bang, finding the oldest stars puts astronomers well within arm’s reach of calculating the absolute age of the universe.
Though previous Hubble research sets the age of the universe at 13 to 14 billion years based on the rate of expansion of space, the universe’s birthday is such a fundamental and profound value that astronomers have long sought other age-dating techniques to cross-check their conclusions.
In 1997, Hubble astronomers broke this impasse, triumphantly announcing a reliable age for the universe calculated from a very precise measurement of the expansion rate.
www.unisci.com /stories/20022/0425022.htm   (848 words)

  
 Galaxy classification - Wikipedia, the free encyclopedia
It has been suggested that Hubble sequence be merged into this article or section.
Astronomers classify galaxies based on their overall shape (elliptical, spiral or barred spiral) and further by the specific properties of the individual galaxy (for example degree of ellipse, number of spirals or definition of bar).
There is an extension to the Hubble sequence that is in wide use; these are the de Vaucouleurs extensions.
en.wikipedia.org /wiki/Galaxy_classification   (711 words)

  
 Hubble sequence   (Site not responding. Last check: 2007-10-21)
Hubble based his classification on photograph s of the galaxies through the telescope s of the time.
Seqhound is a sequence retrieval system that provides access to biological sequence, structure and functional annotation data.
Swiss-Prot is a curated database of protein sequences that are highly annotated and have a minimal level of redundancy.
www.serebella.com /encyclopedia/article-Hubble_sequence.html   (1435 words)

  
 Hubble Heritage
Hubble astronomers expect the light echo to continue to change its appearance and brightness over the next several years.
A dissolve sequence of six images taken by Hubble's Advanced Camera for Surveys shows a CAT-scan-like probe of the three-dimensional structure of the shells of dust surrounding the aging star V838 Monocerotis.
The sequence reveals dramatic changes in the way a brilliant flash of light from the star is reflecting off surrounding dusty cloud structures.
heritage.stsci.edu /2005/02/supplemental.html   (1073 words)

  
 The Hubble Sequence   (Site not responding. Last check: 2007-10-21)
Hubble is perhaps better known for his observations which demonstrated that the Universe is expanding (borne out in the by now infamous Hubble Law), but he was also responsible for another important development of extragalactic astronomy - the Hubble Sequence.
It should not be surprising that Hubble spent many years surveying thousands of galaxies, and during the course of his work, he noticed a trend - galaxies could be ordered into a sequence based on their morphology, the so called Hubble Sequence.
On the left hand side of the sequence, which is commonly called a Tuning Fork diagram, we have the ellipticals which range from E0 up to E7 based on their ellipticity.
www.cv.nrao.edu /~jhibbard/students/CPower/report/report/node3.html   (429 words)

  
 HubbleSite - Release Text about "Hubble Reveals Stellar Fireworks Accompanying Galaxy Collisions"
Earlier Hubble pictures show that nearly a third of very distant galaxies, which existed early in the history of the universe, appear to be interacting galaxies, like the Antennae.
The Hubble observations of the Antennae galaxies, as well as several other nearby colliding galaxies, were conducted by Whitmore (STScI) and co-investigators Francois Schweizer and Bryan Miller (Department of Terrestrial Magnetism, Carnegie Institution of Washington), and Michael Fall and Claus Leitherer (STScI) over the past several years.
Observing other galaxy collisions, the Hubble team discovered the presence of young star clusters which were very bright and blue in the case of ongoing collisions, but had faded to become fainter and redder for the older merger remnants.
www.hubblesite.org /newscenter/newsdesk/archive/releases/1997/34/text   (686 words)

  
 CNN.com - Shuttle grabs Hubble telescope for repairs - March 3, 2002
Columbia is carrying $172 million in new equipment for Hubble, including solar wings, a power-control unit, a steering mechanism, a more advanced camera and a system to restart a disabled infrared camera.
Hubble already has given scientists an impressive view of the universe since it was launched in 1990.
The Hubble Space Telescope is a joint venture of NASA and the European Space Agency.
www.cnn.com /2002/TECH/space/03/03/shuttle.grab/index.html   (425 words)

  
 Hubble sequence
In Hubble's scheme, which is based on the optical appearance of galaxy images on photographic plates, galaxies are divided into three general classes: ellipticals, spirals, and irregulars.
The Hubble sequence classifies spirals on the amount of winding in their spiral arms, tightly wound spirals are type Sa, more open spirals are classed Sc.
The Hubble sequence divides spirals into two classes, normal and barred spirals depending on the prescence of a bar shaped bulge in the galaxy's center.
zebu.uoregon.edu /~js/ast123/lectures/lec11.html   (1332 words)

  
 Physics 7 Lecture #15 - Galaxies   (Site not responding. Last check: 2007-10-21)
Hubble detected Cepheid variables in Messier 31 - the Andromeda Galaxy - and other Local Group galaxies, establishing distances of hundreds of thousands to millions of light years.
Hubble divided galaxies into two principal catagories Elliptical and Spiral, with a third "Irregular" category left to catch those galaxies which defied regulae classification.
Originally Astronomers thought that the Hubble sequence might be an evolutionary sequence with galaxies evolving from right-to-left (or vice versa) along the tuning fork.
cassfos02.ucsd.edu /physics/ph7/Galaxies.html   (1087 words)

  
 Kids.net.au - Encyclopedia Galaxy -   (Site not responding. Last check: 2007-10-21)
He was able to resolve the outer parts of some spiral nebulae as collections of individual stars and identified some Cepheid variables, thus allowing to estimate the distance to the nebulae: they were far too distant to be part of the Milky Way.
The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by Herschel in 1785 by carefully counting the number of stars in different regions of the sky.
In the 1970s it was realized that the total visible mass of galaxies (from stars and gas) does not properly account for the speed of the rotating gas, thus leading to the postulation of dark matter.
www.kidsseek.com /encyclopedia-wiki/ga/Galaxy   (1085 words)

  
 HubbleSite - Release Text about "Hubble Uncovers Oldest "Clocks" in Space to Read Age of Universe"
The new age-dating observations were done by Richer and colleagues by using Hubble to go hunting for elusive ancient stars hidden inside a globular star cluster located 5,600 light-years away in the constellation Scorpius.
Hot, dense spheres of carbon "ash" left behind by the long-dead star's nuclear furnace, white dwarfs cool down at a predictable rate — the older the dwarf, the cooler it is, making it a perfect "clock" that has been ticking for almost as long as the universe has existed.
In 1928, Edwin Hubble's measurements of galaxies made him realize that the universe was uniformly expanding, which meant the universe had a finite age that could be estimated by mathematically "running the expansion backward." Edwin Hubble first estimated the universe was only 2 billion years old.
www.hubblesite.org /newscenter/newsdesk/archive/releases/2002/10/text   (778 words)

  
 Galaxies
The entire main sequence of a cluster is used in the same way to find the distance to the cluster.
The Hubble Law is calibrated using rung 4 methods for nearby galaxy distances and rung 5 methods for larger galaxy distances.
The Hubble Law is also used to determine the overall geometry of the universe (how the gravity of the universe as a whole has warped it).
www.astronomynotes.com /galaxy/s16.htm   (1776 words)

  
 Hubble studies sequences of star formation in neighbouring galaxy
The sequence begins with a cluster of stars outside the top of the Hubble image which led to the birth of the collection of blue- and white-coloured stars near the left of this new Hubble image.
'Grandmother' stars (outside the top of the Hubble image) that have carved a large superbubble, leading to the birth of the cluster of massive blue-white 'mother' stars seen near the top of this image.
This image was taken with Hubble's Wide Field Planetary Camera 2 using filters that isolate light emitted by oxygen (a 1200 seconds exposure) and hydrogen gas (a 1000 seconds exposure).
www.eurekalert.org /pub_releases/2004-07/eic-hss062804.php   (460 words)

  
 Near-Infrared Galaxy Morphology Atlas
The Hubble sequence, at first glance, appears to be simply a qualitative "roadmap" giving convenient names to the wide variety of galaxies observed in the Universe.
Hubble and Humason (1931) understood that the morphological sequence was correlated to the galaxy density environment: galaxy clusters contain more lenticular and elliptical galaxies than the typical field density.
A true infrared/optical "sequence" would have the advantage of being minimally affected from dust extinction-particularly important for understanding bar features-and would be more representative of the stellar populations that dominate the system mass.
spider.ipac.caltech.edu /staff/jarrett/papers/morph/nir_morph.htm   (7144 words)

  
 edwin_hubble   (Site not responding. Last check: 2007-10-21)
Hubble's name is attached to many everyday astronomical life.
A few are: Hubble's zone of avoidance, the Hubble galaxy type, the Hubble sequence, the Hubble time, the Hubble constant, the Hubble luminosity law for reflection nebulae, the Hubble diagram, and the Hubble Space Telescope.
Hubble found that the distant galaxies are moving away from us faster than the ones closer to us.
www.tfsd.k12.id.us /rs/astro/edwin_hubble.htm   (225 words)

  
 Hubble finds the missing pieces of Comet LINEAR
Hubble's powerful vision has settled the fate of the mysteriously-vanished solid nucleus of the comet, which disappeared from the view of Earth-bound telescopes following its passage around the Sun on July 26
Hubble's exceptional resolution and sensitivity allowed it to reveal the nuclei as separated bodies at a level of detail never before seen in a disintegrating comet.
Hubble fortuitously caught a piece blowing off on July 5 - which may have been the first of the cometesimals or a piece of crust.
science.nasa.gov /headlines/y2000/ast07aug%5F1m.htm   (873 words)

  
 ESA Portal - Hubble captures Deep Impact collision with comet
This image is one of a sequence from the NASA/ESA Hubble Space Telescope which shows the comet before and after the impact.
Hubble continued to monitor the comet after the impact, snapping another image 62 minutes after the encounter.
In this photo, the gas and dust ejected during the impact are expanding outward in the shape of a fan.
www.esa.int /esaCP/SEMOOY5DIAE_index_1.html   (305 words)

  
 On the light-profiles of spiral galaxy bulges and the Hubble sequence for spirals   (Site not responding. Last check: 2007-10-21)
On the light-profiles of spiral galaxy bulges and the Hubble sequence for spirals
Abstract: Recent studies have claimed that the Hubble sequence of late-type spirals, and spirals in general, is scale-free.
Within the photometric data used in these works, a trend exists between morphological type and bulge profile shape such that late-type spiral bulges are described by an exponential luminosity profile, where-as the early-type spiral bulges are better described by an $r^{1/2}$ or $r^{1/4}$ law.
www.iac.es /galeria/agraham/Preprints/spiral_conf_99.html   (162 words)

  
 Galaxies: Classification, Formation, and Evolution
Edwin Hubble's discovery of Cepheid variables in the Andromeda Galaxy put to rest any discussion about the Milky Way being the "entire universe." At the time, Hubble was also using the 100-inch Hooker telescope to take thousands of photographic plates of the nebulous objects now known as galaxies.
With the deep field images of the Hubble Space Telescope, and with nearly a century of research since the creation of the "Hubble Sequence," astronomers today question even the relevance of the sequence.
The Hubble researchers are intrigued by the fact that the quasars studied do not appear to have obviously damaged the galaxies in which they live.
www.astro.washington.edu /larson/Astro101/LecturesBennett/Galaxies/galaxies.html   (3079 words)

  
 Kormendy & Bender Revision of the Hubble Sequence for Elliptical Galaxies   (Site not responding. Last check: 2007-10-21)
Kormendy & Bender Revision of the Hubble Sequence for Elliptical Galaxies
The Hubble classification scheme has a well known drawback for elliptical galaxies: the sequence E0-E6 correlates primarily with inclination and not with fundamental properties.
Specifically, we suggest that the Im-spiral-S0 sequence be connected to disky ellipticals and thence to boxy ellipticals.
ifa.hawaii.edu /publications/preprints/96preprints/Kormendy_96-20.html   (216 words)

  
 John Kormendy: Revised Hubble Classification   (Site not responding. Last check: 2007-10-21)
A Proposed Revision of the Hubble Sequence for Elliptical Galaxies
ABSTRACT The Hubble classification scheme has a well known drawback for elliptical galaxies: the sequence E0 - E6 correlates primarily with inclination and not with fundamental properties.
The sequence is continuous from S0s to disky Es.
chandra.as.utexas.edu /~kormendy/tuningfork.html   (220 words)

  
 Top Story - HUBBLE'S INFRARED CAMERA IS BACK IN BUSINESS -- NEW IMAGES RELEASED - June 05, 2002
Sequence starts with Hubble's Wide Field Planetary Camera 2 view, zooms and dissolves to Hubble's composite view from the newly restored NICMOS camera, and dissolves to the NICMOS view, showing the light emitted primarily by hydrogen gas at the center of the galaxy.
Comparison of the new "cryocooler" to the original solid ice cooling method for NICMOS is essentially the same as the comparison of a modern refrigerator to the icebox of one hundred years ago.
Installed on Hubble in February 1997, NICMOS used infrared vision to probe dark, dusty, never-before-seen regions of space with the optical clarity that only Hubble can provide.
www.gsfc.nasa.gov /topstory/20020605nicmos.html   (1105 words)

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