1)one _____ _____ is the distance travelled by light in one year
2)The milky way is a ____galaxy
3)Astronomers have recognised and named ___ constellation
4)The constellation ____has a curving tail and a red super giant star
5)In the sun energy is released when hydrogen is converted into_____
6)Mercury is very hot during the day and very cold at night because it has no _____
7)Venus is the hottest planet because of the ____effect
8)Seasons are caused by the revolution of the earth around the sun and its tilted ______
9)A meteriods that reaches the earths surface is called a _____
10)the moon is a ______satellite of the earth and INSAT 2E is a/an _____satellite of the earth
Answers
Answer:
Stars are classified as supergiants on the basis of their spectral luminosity class. This system uses certain diagnostic spectral lines to estimate the surface gravity of a star, hence determining its size relative to its mass. Larger stars are more luminous at a given temperature and can now be grouped into bands of differing luminosity.[2]
The luminosity differences between stars are most apparent at low temperatures, where giant stars are much brighter than main-sequence stars. Supergiants have the lowest surface gravities and hence are the largest and brightest at a particular temperature.
The Yerkes or Morgan-Keenan (MK) classification system[3] is almost universal. It groups stars into five main luminosity groups designated by roman numerals:
I supergiant;
II bright giant;
III giant;
IV subgiant;
V dwarf (main sequence).
Specific to supergiants, the luminosity class is further divided into normal supergiants of class Ib and brightest supergiants of class Ia. The intermediate class Iab is also used. Exceptionally bright, low surface gravity, stars with strong indications of mass loss may be designated by luminosity class 0 (zero) although this is rarely seen.[4] More often the designation Ia-0 will be used,[5] and more commonly still Ia+.[6] These hypergiant spectral classifications are very rarely applied to red supergiants, although the term red hypergiant is sometimes used for the most extended and unstable red supergiants like VY Canis Majoris and NML Cygni.[7][8]
The "red" part of "red supergiant" refers to the cool temperature. Red supergiants are the coolest supergiants, M-type, and at least some K-type stars although there is no precise cutoff. K-type supergiants are uncommon compared to M-type because they are a short-lived transition stage and somewhat unstable. The K-type stars, especially early or hotter K types, are sometimes described as orange supergiants (e.g. Zeta Cephei), or even as yellow (e.g. yellow hypergiant HR 5171 Aa).[9]
Explanation:
Answer:
the period of revolution of Halley's Comet