Spectral Class
Related Category: Astronomy: General
in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C. Pickering began the first extensive attempt to classify the stars spectroscopically.
Spectral class
In astronomy one method of classifying stars is through the analysis of their absorption spectra, by this method stars are assigned a spectral class.
spectral class
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Essential reading Compare
side-by-side A Dictionary of Astronomy The Columbia Encyclopedia, Sixth Edition ...
Spectral Classes
Table of Spectral Class Features
Luminosity Classes ...
Harvard Spectral Classification
The absorption features present in stellar spectra allow us to divide stars into several spectral types depending on the temperature of the star.
SPECTRAL CLASSIFICATION
Stellar spectra like those shown in Figure 17.12 were obtained for many stars well before the start of the twentieth century as observatories around the world amassed spectra from stars in both hemispheres of the sky.
spectral class
the designation of a star based on its spectrum, which is determined by its surface temperature
spectral line ...
spectral class Classification scheme, based on the strength of stellar spectral lines, which is an indication of the temperature of a star.
SPECTRAL CLASS - Classification scheme, also called the "Harvard Spectral Sequence," based on the strength of stellar spectral lines, which indicate a star's temperature.
Spectral Class
A star's position in the temperature classification system O,B,A,F,G,K, and M. Based on the appearance of the star's spectrum.
Spectral Sequence ...
Spectral Classification
Commonly, the system devised by Annie Cannon combining the perceived colour of a star with its spectral characteristics.
Spectral Class - A categorization, based on the pattern of spectral lines of stars, that groups stars according to their surface temperatures
Spectrograph - A device used to produce and record a spectrum ...
The Yerkes spectral classification, also called the MKK system from the authors' initials, is a system of stellar spectral classification introduced in 1943 by William Wilson Morgan, Phillip C. Keenan and Edith Kellman from Yerkes Observatory.
Spectral Classes
Star Type Color Approximate Surface Temperature Average Mass (The Sun = 1) Average Radius (The Sun = 1) Average Luminosity (The Sun = 1) Main Characteristics Examples O
Blue
over 25,000 K ...
Spectral classes are further subdivided by Arabic numerals (0-9). For example, A0 denotes the hottest stars in the A class and A9 denotes the coolest ones.
Spectral Class (Spectral Type)
A classification scheme that groups stars according to their surface temperatures and spectral features.
Spectral Line ...
SPECTRAL CLASS
Spectral classes are groups of stars that have similar characteristic emission lines in their spectra (indicating that they have similar compositions).
A spectral classification system for stars; see MKK system. [H76]
Ylem ...
Its spectral class is A0 V (Sirius, an A1 V, is slightly less luminous) and it is firmly in the main sequence (dwarf), fusing hydrogen to helium in its core. It is twice as massive as our Sun and about fifty times as luminous.
The spectral classes are based on the spectrum lines of the star. So, the elements present in the star can be known once the spectral class is known.
The spectral classification system has been pretty steady for more than 70 years. However, there have been some studies that have come up with some stars that are even cooler than M types. These have been labeled the L and T type stars.
1. What spectral class of star is needed to ionize an H II region?
O stars and only the hottest of the B stars (B0 and B1).
2. Why does a reflection nebula appear blue?
The Sun, a spectral class G2 star that contains 99.86% of system's mass.
The planets of the solar system are those nine bodies traditionally labelled as such; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
Yellow Giant (Spectral Class G5 III). Approximately the same color and temperature as the sun but a giant star.
How Far Away:
46 light years ...
Problems with spectral classification Originally, spectral designations were based on inferences of an asteroid's composition.
Stars arranged by spectral class and variable star class using proper names.
Stars arranged by spectral class and variable star class using Greek letter names.
The Natures of the Stars provides a linked introduction to stars and star lives.
Stars of different spectral classes have different mean orbital velocities.
Which is hotter, a spectral class A star or an F star? If you saw strong hydrogen lines in a star's spectrum, what spectral class would it likely be?
Star A and Star B have the same spectral type and luminosity.
peculiar stars (NASA Thesaurus) Stars with spectra that cannot be conveniently fitted into any of the standard spectral classifications. They are denoted by a "p" after their spectral type.
Including Sol itself, around 74 "bright" stars (spectral classes O, B, A, F, G, and K) are currently believed to be located within 10 parsecs (or 32.6 light-years) of Sol.
Here is a list of 70 of the brighter stars, including common names, Bayer names, positions on the celestial sphere, and spectral class.
The Flamsteed Naming System ...
In the more modern system of spectral classification, called the MK system (after the American astronomers William W. Morgan and Philip C. Keenan who introduced it), luminosity class is assigned to the star along with the Draper spectral class.
Stars are divided into groups called spectral types (also called spectral classes) which are based on the strength of the hydrogen absorption lines.
Other attributes of the Diagram are the Spectral Classifications: O, B, A, F, G, K, M. These are used by astronomers as basic categories into which the stars can be placed, for all stars within a spectral class share some very basic characteristics.
It measures the luminosity of a star versus it's spectral class. When you plot many stars on such a diagram, you will find that most stars fall along a single straight line running diagonally across the chart. This is known as the main sequence.
Its spectral classification is "G2 V." The G2 part basically means it's a yellow-white star, and the roman numeral V means it's a "main sequence" dwarf star (by far the most common) as opposed to supergiant, or sub-dwarf, etc.
Below is a version of the Hertzsprung-Russell diagram, which shows how the size, color, luminosity, spectral class, and absolute magnitude of stars relate.
A classical Cepheid is a young, Helium-burning, supergiant star (spectral class F-K) that regularly pulsates in size and changes in brightness (with a period from 1-50 days).
classification used to sort stars by photospheric temperature and intrinsic brightness. The seven spectral classes O-B-A-F-G-K-M, listed in order of decreasing temperature, include 99% of all known stars.
spectral sequence - The sequence of spectral classes of stars arranged in order of decreasing temperatures of stars of those classes.
Stars are assigned to different spectral classes.
Edit Parts of stars
corona
stellar core
chromosphere ...
Early-type star. Any hot star of spectral class O, B or A. Sometimes referred to as 'early spectral-type.
Various types of star - spectral classes A, F, G, K and M (A stars are hotter, whilst M stars are cooler red dwarfs) - have been targeted in the survey.
Some of them may burn out, leaving inert residues of stony material-possibly cataloged in some cases as Apollo asteroids of spectral class C, P or D.
Brightest Stars: Antlia is a faint constellation void of bright stars. Its least faint star is α Ant: being Antlia's principal star its apparent brightness is still only 4.25 mag. Its spectral class is K4 III.
Beta Hydri is also the closest confirmed subgiant star to Sol and one of the older as well as highly evolved stars of the Sun's spectral class in the Solar neighborhood. It is a member of the Zeta Herculis stellar moving group.
 See also: Star, Light, Giant, Distance, Sun
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