Stars and the Night Sky Flashcards
What is an Asterism?
part of a bigger constellation (e.g. Orions belt)
What does it mean if the the star has a smaller magnitude?
It is brighter star
what happens if the stars magnitude is >6?
You cannot see it with the naked eye.
What colour are little stars?
yellow
what size is the star if it is blue?
big (bigger than yellow stars)
what colour is and old star?
Red
what temperature is a red star?
3 000 kelvin (cool)
what stars are around 6 000 kelvin?
yellow stars (like the sun)
how hot are blue stars?
12 000 kelvin
What is declination?
(in degrees) is the sky equivalent of latitude. the celestial equator is 0 degrees, directly above the south pole is -90 degrees.
What is right ascension?
(in hours and minutes) is the sky equivalent of longditude. it is measured from a point in Pisces, ORA (it used to be in Aries).
what is a double star?
2 stars that appear close in the sky but in relaity are very far apart.
What do you call 2 stars which orbit each other?
binary stars
What are eclipsing binary stars?
where the binary stars pass in front of each other: the when the little star is infront there is a secondary eclispe where the magnitude drops slightly but when the bigger star is infront there is a secondary eclispe and the magnitude drops alot.
what does M = m+5(logd) work out?
how bright a star is
What is trigonometric parallax?
This depends on the apparent motion of near by stars compared to more distant stars.
how do you work out the distance to a star?
D = 1 / parallax angle (arcseconds)
What is a Stellar nebula?
Where stars are born (protostars are formed in it when hydrogen is converted into helium)
what are the two main sequence stars?
yellow dwarf and blue super giant
what are the two types of red star?
red giant and red super giant
what does a red giant star turn into?
planetary nebula
what does a red super giant turn into?
Supernova (the star reaches high enough temperatures to turn helium into carbon)
why does a planetary nebula turn into a white dwarf?
because the carbon continues to contract. Once it can’t contract any more its supported by electron pressure making it a white dwarf.
what does a white dwarf turn into?
a black dwarf
what does supernova create?
a black hole or a neutron star
What does OBAFGKM mean?
it is a way of star classification.
What does O mean in the OBAFGKM?
ionized and neutral helium, blue, 31000k+
What does B mean in the OBAFGKM?
neutral helium, stronger hydrogen, blue-white, 9750k - 31000 k
What does A mean in the OBAFGKM?
strong hydrogen, ionized metals, white, 7100-9750 K
What does F mean in the OBAFGKM?
weak hydrogen, ionized metals, yellow-white, 5950-7100 K
What does G mean in the OBAFGKM?
weaker hydrogen, ionized+neutral metals, yellow 5250-5950 K
What does K mean in the OBAFGKM?
weaker hydrogen, neutral metals, orange, 3800-5259 K
What does M mean in the OBAFGKM?
little hydrogen,neutral metals, molecules, red, 2200-3800k
What is the Herztsrung Russell Diagram?
The HR diagram a tool to study star evolution. it plots temperature of the stars against luminosity or colour against their absolute magnitude.
What is a Parsec?
the distance to a star with a parallax angle of 1 second of an arc.
how do you work out distance to a star?
distance (parsecs) = 1/parallax angle (seconds of arc)
