stars below about 1.5 times the mass of the sun are a type of star found on the lower end of the main sequence, based on its spectral class.
stars below about 1.5 times the mass of the sun are a type of star found on the lower end of the main sequence, based on its spectral class.
which is a type of star found on the lower end of the main sequence, based on its spectral class?
stars below about 1.5 times the mass of the sun
at a stellar core temperature of 18 million kelvin, the pp process and cno cycle are equally efficient, and each type generates half of the star's net luminosity. as this is the core temperature of a star with about 1.5 , the upper main sequence consists of stars above this mass. thus, roughly speaking, stars of spectral class f or cooler belong to the lower main sequence, while a-type stars or hotter are upper main-sequence stars. the transition in primary energy production from one form to the other spans a range difference of less than a single solar mass. in the sun, a one solar-mass star, only 1.5% of the energy is generated by the cno cycle. by contrast, stars with 1.8 or above generate almost their entire energy output through the cno cycle.
main sequence
four principal stars, delta, gamma, epsilon, and beta corvi, form a quadrilateral asterism known as "the "spica's spanker" or "the sail". although none of the stars are particularly bright, they lie in a dim area of the sky, rendering the asterism easy to distinguish in the night sky. gamma and delta serve as pointers toward spica. also called gienah, gamma is the brightest star in corvus at magnitude 2.59. its traditional name means "wing", the star marking the left wing in bayer's "uranometria". 154±1 light-years from earth, it is a blue-white hued giant star of spectral type b8iii that is times as massive, and 355 times as luminous as the sun. around million years old, it has largely exhausted its core hydrogen and begun expanding and cooling as it moves away from the main sequence. a binary star, it has a companion orange or red dwarf star of spectral type k5v to m5v that is about 0.8 times as massive as the sun. around 50 astronomical units distant from gamma corvi a, it is estimated to complete an orbit in 158 years. delta corvi, traditionally called algorab, is a double star divisible in small amateur telescopes. the primary is a blue-white star of magnitude 2.9, around 87 light-years from earth. an enigmatic star around 2.7 times as massive as the sun, it is more luminous (65–70 times that of the sun) than its should be for its surface temperature of 10,400 k, and hence is either a 3.2 million year-old very young pre-main sequence star that has not settled down to a stable main sequence life stage, or a 260-million-year-old star that has begun to exhaust its core hydrogen and expand, cool and shine more brightly as it moves away from the main sequence. its spectral type is given as a0iv, corresponding with the latter scenario. warm circumstellar dust—by definition part of its inner stellar system—has been detected around delta corvi a. delta corvi b is an orange dwarf star of magnitude 8.51 and spectral class k, also surrounded by circumstellar dust. a post t-tauri star, it is at least 650 au distant from its brighter companion and takes at least 9400 years to complete an orbit. delta corvi's common name means "the raven". it is one of two stars marking the right wing. located 4.5 degrees northeast of delta corvi is struve 1669, a binary star that is divisible into two stars 5.4" apart by small amateur telescopes, 280 light-years from earth. the pair, both white stars, is visible to the naked eye at magnitude 5.2; the primary is of magnitude 5.9 and the secondary is of magnitude 6.0.
corvus (constellation)