Exploring Starlight Flashcards
What is Apparent Magnitude?
Apparent Magnitude is the brightness of a object in the sky from Earth
What is Absolute Magnitude?
Absolute Magnitude is the brightness of a celestial object at 10 parsec
Which is brighter? A star with a magnitude of 6 or a star with a magnitude 2?
The star with magnitude of 2 is brighter then the star with a magnitude of 6.
How many times brighter is a star with a magnitude of 5 compared to a magnitude of 6?
Magnitude 5 is 2.5x brighter then magnitude 6, each time the magnitude goes up by 1 it is 2.5x brighter
What is the distance modulus formula
M = m+5 - (5 log d)
What does the distance modulus formula find out?
The distance modulus formula determines the apparent or absolute magnitude of a star
What information can be obtained from a stellar spectrum.
Chemical Composition, Temperature, radial velocity, sunspot cycle, wavelength
Understand how stars are classified according to the spectral type?
It uses the Morgan Keenan System (O,B,A,F,G,K,M) with M being the coolest of the stars and O being the hottest.
How are stars colour and spectral type related to their temperature.
The surface temperature of a star determines the colour light it emits. Blue stars are hotter then yellow stars, which are hotter then red stars
How does a stars life cycle relate to the Hertz Sprung Russel Diagram(Those weird clumped up areas of stars diagram)
Stars life cycle relates to the OBAFGKM which determines its position on the HR diagram with M being the longest living and O being the shortest
What the inverse square relationship between distance and brightness/intensity.
1/d2 or I/d2
How many arc seconds are in a arc minute
60 arc seconds
How many arc seconds are in a degree?
3600 arc seconds (60 arc minutes)
What is a parsec?
The distance to a star.
How to use the Hertz Sprung Russel Diagram to determine the distance to a star
Use Spectroscopic parallax which uses luminosity and temperature which you can use from the HR Diagram
What is a binary star?
A binary star is a stellar system consisting of two stars orbiting around their centre of mass.
What is a eclipsing binary?
An eclipsing binary is two stars moving in an orbit in line to Earth . That the light at one time can be hidden behind the other like a eclipse.
Which of the following are used by astronomers to show how the brightness of a star varies over time.
A. Light Curve
B.Light Graph
C.Light Sabre
A. Light Curve
What is a cataclysmic star?
A star which irregularly increases in brightness by a large factor then drop back down
What is a Cephied star?
A Cephied variable is a type of star that pulsates radially varying in both diameter and temperature and produces changes in brightness
When a star expands does its temperature fall or increase?
When a star expands the temperature falls.
Using primary and secondary star, explain the cause of the variability in an eclipsing binary.
The primary and secondary stars are not aligned giving rise to constant brightness. The smaller/secondary dip occurs when the secondary star occurs is behind the primary star.
How do you find apparent magnitude using distance modulus formula.
m = M - 5 + (5 log d) (d = parsec)
Name one the following are not bound together by gravitation?
Double stars
What is a RR Lyrae variable.
RR Lyrae variable stars are periodic variable stars commonly found in global clusters.
HR Diagram/Spectroscopic: Which object splits up light from astronomical objects into a spectrum?
Diffraction grating
Hertzsprung russell diagram are usually obtained by plotting? etc luminosity to temperature
luminosity against spectral type
Which star is the hottest? A. B4 B. A9 C. B8 D. A6
A.B4
What is the spectral type of the sun
G2
Explain the connection line between dark absorption lines and the chemical composition of the stars
Light passing through outer layers of a star is made of all wavelengths/energies; some of this light has the correct wavelength/energy to excite atoms in the stars outer layer
When the atoms de-excite
They emit radiations/photons of the same wavelengths energy but in a random direction
Exploring starlight: How many times does star a appear brighter than star b.
Star a = 0.8
Star b = 1.8
2.5x brighter
How many times does star B appear brighter than star y
Star b = 1.8
Star y = 3.8
6.25x brighter
How to do it: 3.8 - 1.8 = 2.5^2(to the power of 2) = 6.25
how many light years are in 1 parsec
3.26 ly
In a constellation, star b appears brighter then star e by a factor of 16
The apparent magnitude of e is 3.7; deduce the apparent magnitude of B
square root 16 to the power of 2.5 which rounded is equal to 3 and do 3.7-3 = 0.7
Apparent magnitude of b = 0.7
In a constellation, the brightest star a appears 40 times brighter than the faintest star N
The apparent magnitude of a is 0.3 deduce the star of magnitude of N
Square root 40 to the power of 2.5 = 4.37
At its faintest, A sco is 250x brighter than a globular cluster that lies close to Scorpius
Deduce the apparent magnitude of the globular cluster
A = 0.9
Square root 250 by 2.5 = 9.1 - 0.9 = 8.2 apparent magnitude
What is a astronomical unit
Average distance from the centre of the earth to the distance to the centre of the sun.
How do you find distance in parsec.
Distance = 1/parralax angle
Parralax angle = 1/distance
How many arc seconds and arc minutes are in half a degree.(0.5)
1800 seconds are in half a degree which is 30 arc minutes in a degree
A star has a parallax angle of 0.25 degrees how far away is the star.
distance = 1/parallax angle = 1/0.25 = 4 parsec
Which types of telescopes can be located at sea level?
A. infra red and optical telescopes
B. optical and radio telescopes
C. Radio and gamma-ray telescopes
D. X-ray and optical telescopes
B. optical and radio telescopes
Which two types of electromagnetic radiation are not blocked by the Earths Atmosphere
Visible light and radio waves do not get blocked
To determine the structure and rotation of our Galaxy (the Milky Way), astronomers often use electromagnetic radiation with a wavelength of 21 cm. In which region of the electromagnetic spectrum does this radiation lie?
Radio Waves
The ratio of the diameters of objective elements for a radio telescope and an optical telescope is 6000:1. The corresponding ratio of wavelengths is 360000:1
Determine the ratio: resolution of optical telescope / resolution of radio telescope
360000/6000 = 60 or 1/60 if inverse square law
