Estimate the Kelvin-Helmholtz lifetime in year of a 17 solar
mass main sequence star. You will...
Estimate the Kelvin-Helmholtz lifetime in year of a 17 solar
mass main sequence star. You will need the mass-luminosity relation
and main sequence stellar class G0.
A main sequence star has the spectral classification of B5.
Estimate its luminosity from the HR diagrams in your text. Explain
in words how you can find its distance. What is this method of
finding stellar distance called?
(please type not write down the answer) astronomy
3. A main sequence star of mass 15 M⊙ has a luminosity of
approximately 10,000 L⊙ . a. At what rate does mass vanish as H is
fused to He in the star’s core? Note: When we say “mass vanish”
what we really mean is “gets converted into energy and leaves the
star as light”. b. At what rate is H converted into He? To do this
you need to take into...
1. The first set of data you receive is a spectrum of a main
sequence star taken with the MacDonald Spectrometer onboard HST.
Based on the fact that the star’s spectrum has strong Hydrgen
absorption lines and many molecular absorption lines, what spectral
type do you believe this star to be? Explain.
2. Based on this star’s spectral type, explain the evolutionary
stages that it will go through after it completes the main sequence
phase of its life. How will...
A 1
solar mass star has two planets. One is observed to transit every
year and the other twice a year. If their orbits are circular, how
can you determine the distance between their orbits? How could the
transits show that they are circular? How might transit
observations provide estimates of the density of the planets? How
could you tell if the orbits were parallel to the star's spin
axis?
1. What is the chemical composition of the core of a one solar
mass star during the red super giant (asymptotic giant) phase? a)
mainly carbon and oxygen b) mainly helium c) mainly hydrogen 2.
What kind of stellar remnant will be left when the sun dies? a) red
giant b) black hole c) white dwarf d) neutron star Which of the
following Is not true of the cosmic background radiation? a) it is
nearly equally bright in all directions...
a) At what distance from a 2 solar mass neutron star would a
planet like the Earth be tidally disrupted (that is, literally
pulled apart)? That is, how close would the planet need to be to
the NS for the difference between the NS’s gravity at the center of
the planet and at the surface of the planet to be greater than the
gravity holding the planet together?
b) Would the asteroid Pallas be able to get any closer? (Pallas...
Describe the life history of a 1 solar mass star from the
moments after the helium flash when the star moves into the
horizontal branch through to the white dwarf stage. Include as many
details as possible and describe its evolutionary track on the H-R
diagram as it progresses.
Explain (in your own words) the shape of the Hayashi track for a
pre-main sequence star, noting the
most important physical changes that occur in a star as it moves
from being a collapsing cloud of
gas to being a hydrogen burning main sequence star. Explain how
this varies for low and high mass
stars. What is the best wavelength range to detect pre-main
sequence stars, explain why.
Please answer all sections as they are about the same
concept.
We observe a B-type main sequence star (MV = -1.1) in the
direction of a large region of interstellar gas and dust. The
visual extinction looking through the cloud is 1.1 magnitudes. The
thickness of the nebula is estimated to be 20 pc and its center is
located 700 pc from Earth.
a. If the star is in front of the nebula, what would be its
apparent visual magnitude?
b. If the star is behind the nebula, what would be...