Largest Star by Massive : pistol star
-200 times of solar mass
-25000 light years far away
Largest Star by Luminosity : LBV 1806-20
-38 million solar luminosity
-30000-40000 light years far away
Largest Star by Radius : VY Canis Majoris
-1800 radii
-5000 light years far away
How could they know?
Massive-Star birth
Giant molecular cloud, GMC collapse because of the instability gravitational of the molecules.
And it became a protostar. Which some of them have larger mass than the sun but some don’t.
Luminousity
apparent magnitude
Δm = mf − mb
2.512Δm = ΔL
mf-magnitude number of a brighter star
mb- magnitude number of a fainter star
ΔL- variation in brightness
Radius
Angular size
It means if it far the angular size is small so we have to use the things to help.
Angular size(arc second) = size(km) / distances(parsec)
Things help to find angular size.
1.Inferometer
2. Telescope
Largest Star by Radius : VY Canis Majoris
-1800 radii
-5000 light years far away
How could they know?
Massive-Star birth
Giant molecular cloud, GMC collapse because of the instability gravitational of the molecules.
And it became a protostar. Which some of them have larger mass than the sun but some don’t.
Luminousity
apparent magnitude
Δm = mf − mb
2.512Δm = ΔL
mf-magnitude number of a brighter star
mb- magnitude number of a fainter star
ΔL- variation in brightness
Radius
Angular size
It means if it far the angular size is small so we have to use the things to help.
Angular size(arc second) = size(km) / distances(parsec)
Things help to find angular size.
1.Inferometer
2. Telescope
ไม่มีความคิดเห็น:
แสดงความคิดเห็น