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Topic: Absolute magnitude


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In the News (Wed 20 Mar 19)

  
  Absolute magnitude - Wikipedia, the free encyclopedia
In defining absolute magnitude it is necessary to specify the type of electromagnetic radiation being measured.
Many stars visible to the naked eye have an absolute magnitude which is capable of casting shadows from a distance of 10 parsecs; Rigel (−7.0), Deneb (−7.2), Naos (−7.3), and Betelgeuse (−5.6).
In this case, the absolute magnitude is defined as the apparent magnitude that the object would have if it were one astronomical unit (au) from both the Sun and the Earth and at a phase angle of zero degrees.
en.wikipedia.org /wiki/Absolute_magnitude   (843 words)

  
 Apparent magnitude - Wikipedia, the free encyclopedia
The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth.
The absolute magnitude, M, of a star or galaxy is the apparent magnitude it would have if it were 10 parsecs (~ 32 lightyears) away; that of a planet (or other solar system body) is the apparent magnitude it would have if it were 1 astronomical unit away from both the Sun and Earth.
The absolute magnitude of the Sun is 4.83 in the V band (yellow) and 5.48 in the B band (blue).
en.wikipedia.org /wiki/Apparent_magnitude   (1197 words)

  
 absolute magnitude concept from the Astronomy knowledge base   (Site not responding. Last check: 2007-10-21)
Absolute magnitude is defined as the apparent magnitude the star or galaxy would have if it were 32.6 light-years (10 parsecs) from Earth.
A star that is one absolute magnitude brighter than another (e.g., +4 versus +5) is 2.5 times intrinsically brighter; a star that is 5 absolute magnitudes brighter is 100 times intrinsically brighter; and a star that is 10 absolute magnitudes brighter is 10000 times intrinsically brighter.
has definition The absolute magnitude (g) of a solar-system body such as an asteroid is defined as the brightness at zero phase angle when the object is 1 AU from the Sun and 1 AU from the observer.
www.site.uottawa.ca:4321 /astronomy/absolutemagnitude.html   (239 words)

  
 Absolute Visual Magnitude - Hutchinson encyclopedia article about Absolute Visual Magnitude   (Site not responding. Last check: 2007-10-21)
In astronomy, measure of the intrinsic brightness of a celestial body in contrast to its apparent brightness or magnitude as seen from Earth.
For a non-self-luminous body, such as an asteroid, the absolute magnitude is the magnitude it would appear to have if it were one astronomical unit (149.6 million km/92.6 million mi) from both the Sun and the Earth with the phase angle zero.
For a self-luminous body, such as a star or galaxy, the absolute magnitude is the magnitude it would appear to have if it were at a distance of 10 parsecs or 32.616 light years.
encyclopedia.farlex.com /Absolute+Visual+Magnitude   (162 words)

  
 Magnitude   (Site not responding. Last check: 2007-10-21)
Apparent magnitude is the brightness of an object as it appears to an observer on Earth.
Absolute magnitude on the other hand is a measure of intrinsic luminosity, regardless of how far away objects are.
Photographic magnitude is the magnitude measured by a standard photographic emulsion, which responds chiefly to the blue and violet part of the spectrum (although different photographic materials have very different colour responses).
www.historyoftheuniverse.com /magnitude.html   (618 words)

  
 What Is Visual Magnitude?   (Site not responding. Last check: 2007-10-21)
This means a difference in magnitudes of 5 units (from magnitude 1 to magnitude 6, for example) corresponds to a change in brightness of 100 times.
Absolute magnitude is defined as how bright a star would appear if it were exactly 10 parsecs (about 33 light years) away from Earth.
Absolute magnitudes are often written with a capital (upper case) "M".
liftoff.msfc.nasa.gov /academy/universe/MAG.HTML   (385 words)

  
 Absolute magnitude: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-10-21)
The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received...
Sirius (α cma / α canis majoris / alpha canis majoris) is the brightest star in the nighttime sky, with a visual apparent magnitude of −1.46....
Absolute magnitudes for stars generally range[Click link for more facts about this topic] from -10 to +17.
www.absoluteastronomy.com /encyclopedia/a/ab/absolute_magnitude.htm   (2248 words)

  
 Stellar Magnitudes
The former is a convolution of the true brightness and the effect of distance on the observed brightness, because the intensity of light from a source decreases as the square of the distance (the inverse square law).
The apparent magnitude of various objects determined using light from the visible part of the spectrum is given in the adjacent table.
The brightness of an object (whether apparent or absolute) depends on the wavelength at which we observe it, as we saw clearly in the discussion of radiation laws.
csep10.phys.utk.edu /astr162/lect/stars/magnitudes.html   (802 words)

  
 absolute magnitude of stars   (Site not responding. Last check: 2007-10-21)
A star’s absolute magnitude is the apparent magnitude it would have if it were 10 parsecs away (an arbitrarily chosen distance) and there were no intervening gas or dust.
Absolute magnitude is calculated from the star's apparent magnitude and its distance.
The absolute bolometric magnitude of a star is the bolometric magnitude it would have if it were at a distance of 10 parsecs.
www.sizes.com /units/magnitude_absolute.htm   (196 words)

  
 Project Glossary   (Site not responding. Last check: 2007-10-21)
Absolute magnitude is a fixed way of representing the magnitude of a star without the effects of its distance from the Earth.
Apparent magnitude is the magnitude of a star's intensity as measured from the Earth.
Magnitudes are on a logarithmic scale to model the fact that the human eye perceives intervals of brightness as ratios, rather than differences, of intensity.
www.rpi.edu /~linc/ProjectGlossary.html   (520 words)

  
 Chapter 8 Review Questions   (Site not responding. Last check: 2007-10-21)
The absolute magnitude is the magnitude that the stars would have if they were all at a common distance from the observer (at 10 parsecs).
The absolute visual magnitude is then related to the intrinsic brightness of the star in the visible portion of the electromagnetic spectrum.
The absolute visual magnitude is related to the portion of the total luminosity emitted only in the visible portion of the electromagnetic spectrum.
www.goshen.edu /nasc/NaSc200/ReviewQuestions/ch8review.html   (926 words)

  
 Cool Cosmos
Luminosity is also referred to as the absolute magnitude or absolute brightness of an object.
The apparent magnitude or apparent brightness of an object is a measure of how bright an object appears to be to an observer.
absolute magnitude = apparent magnitude - 5 × log(distance in parsecs) + 5.
coolcosmos.ipac.caltech.edu /cosmic_classroom/cosmic_reference/luminosity.html   (535 words)

  
 Troubled Times: Magnitude
The scale is logarithmic, so, a difference in magnitude of 8 (between the actual and apparent magnitude of the 12th) consists in a factor of nearly 3000.
A magnitude of 10 is reasonable for an object the size and distance of the 12th planet.
Hence, telescopes, designed to measure magnitude by assuming that light is emanating from the full area of a sphere, classify it as magnitude 11.0, and the actual magnitude from the vantage point of earth is 11.0, regardless of whether certain faint, irregular hisps of light occasionally make it to earth with magnitude 2.0 brightness.
www.zetatalk.com /theword/tword03k.htm   (780 words)

  
 Stellar Magnitude
The magnitude scale, like the sensitivity of the naked eye, is logarithmic and, by convention, defined so that brighter stars have smaller magnitude values.
Absolute magnitude is the apparent magnitude that a star would have if it were located at a standard distance of 10 parsecs from the Earth.
Apparent and absolute magnitudes are measured by instruments sensitive to a small wavelength interval of the radiation continuum, such as the visual band: approximately 400 nm/7
www.peripatus.gen.nz /Astronomy/SteMag.html   (454 words)

  
 Brightest
Originally the plan was to call the brightest visible stars "stars of the first magnitude" or magnitude = 1 and on down to the faintest visible "stars of the sixth magnitude" or magnitude = 6.
The absolute magnitude is the magnitude the stars would have if viewed from a distance of 10 parsecs or some 32.6 light years.
Absolute magnitudes are how bright a star would appear from some standard distance, arbitrarily set as 10 parsecs or about 32.6 light-years.
exobio.ucsd.edu /Astronomy/brightest.htm   (496 words)

  
 Magnitude   (Site not responding. Last check: 2007-10-21)
The brightest stars were given a magnitude of 1 and the dimmest stars a magnitude of 6.
Absolute magnitude, M. The absolute magnitude of a star, M - is really a league table of how bright stars are compared to each other.
By measuring, the apparent magnitude in the night sky, m and knowing the absolute magnitude M, the distance can easily be calculated.
freespace.virgin.net /gareth.james/astro/alevel/magnitude.html   (580 words)

  
 [No title]
Magnitudes --- are the astronomical way of talking about the brightness (energy per unit time entering the eye or a detector) or luminosity (energy per unit time emitted) of objects.
Apparent Magnitude --- The magnitude that is measured depends both on how bright an object is intrinsically and how far away it is. Light falls off as the square of the distance from an object, the inverse square law.
Absolute Magnitude --- To facilitate comparison between intrinsic luminosities, it is essential to remove the effects of distance.
www.ifa.hawaii.edu /~acowie/class99b/class_15.html   (988 words)

  
 [No title]
1st magnitude described the brightest stars; 2nd magnitude the 2nd brightest, and so on down to 6th magnitude which described the faintest that could normally be seen by the naked eye.
Apparent magnitude depends on both the luminosity of the star (energy per unit time in the wavelength band of interest) and distance through the inverse-square law of light.
Absolute magnitude is the apparent magnitude of the astro-body as measured at 10 parsecs (or about 32.62 lyr) (Cl-8): see parsec.
www.physics.unlv.edu /~jeffery/astro/magnitude/magnitude.html   (835 words)

  
 SkyEye - Brightest Stars
Thus, a star of magnitude -1 is brighter than one of magnitude +1 which in turn is brighter than one of magnitude +6.
Absolute magnitude, however, is the brightness of a star supposing that it was located exactly 10 parsecs (about 32.6 light years) away from Earth.
We use the apparent magnitudes of stars to form constellations but we use the absolute magnitudes of stars to tell us something about their physics.
www.obliquity.com /skyeye/misc/bright.html   (361 words)

  
 More About Stars
The magnitude system originated with Hipparchus in the second century B.C.  He grouped the stars into six categories by brightness.  The brightest stars were assigned to the “first magnitude” group and the faintest to the “sixth magnitude group.”  Stars corresponding to sixth magnitude are the faintest stars visible to the naked eye.
To modernize the magnitude system, we define the scale such that a difference of five magnitudes is exactly a factor of 100 in apparent brightness.  Also, the scale is extended to magnitudes smaller than 1 and larger than 6.  Decimal magnitudes are also permitted.
A star’s absolute magnitude is equal to the apparent magnitude that it would have if located at a distance of 10 pc from the observer.
www.physics.rutgers.edu /~abragg/110/lecture7.html   (750 words)

  
 Stars' Brightness   (Site not responding. Last check: 2007-10-21)
A star brighter than another one by one magnitude puts out 2.5 times more light, it doesn't matter whether one is magnitude 3 and the other magnitude 4, or whether one is magnitude 26 and the other one is magnitude 27.
Presently, all magnitudes are measured with a photometer mounted on a telescope.
Absolute magnitude is related to the luminosity of the star, which is the amount of energy that a star gives off per second.
www.mira.org /fts0/stars/115/txt001w.htm   (1068 words)

  
 Properties of Stars
The other intervals of magnitude were based on the 19th century belief of how the human eye perceives differences in brightnesses.
On the quantified magnitude scale, a magnitude interval of 1 corresponds to a factor of 100
The absolute magnitude is a measure of the star's luminosity---the total amount of energy radiated by the star every second.
www.astronomynotes.com /starprop/s4.htm   (1430 words)

  
 Zoom Astronomy Glossary: A
Absolute magnitude is a measure of the inherent brightness of a celestial object.
Albireo (beta Cygni) is a third magnitude star in the constellation called Cygnus (Albireo is the head of the swan and the second-brightest star in Cygnus).
Apparent magnitude is a measure of the brightness of a celestial object as seen from Earth.
www.enchantedlearning.com /subjects/astronomy/glossary/index.shtml   (4918 words)

  
 Telescopes In Education (TIE) - User Guide
Magnitude measurements are proportional to light intensity and distance.
If we can assure that two stars being measured for magnitude are at the same distance, then the ratio of their light intensity (magnitude) should be the same regardless of their distance from us.
When the apparent magnitudes of stars in an open cluster are measured, the diffrences of their apparent magnitudes must also be the differences of their absolute magnitudes.
www.telescopesineducation.com /workbook/project_7.html   (1039 words)

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