Type I supernovas

what are binary stars?

two stars that orbit around a common centre of mass due to their mutual gravitation

what do binary stars have to do with centre of masses? how does it work?

they orbit around a centre of mass and if 2 stars have equal mass, the centre of mass is between them, but if one star is more massive, the centre of mass shifts closer to the more massive star.

How do binary stars move in relation to their common center of mass, and what is the shape of their orbits?

each star executes an elliptical orbit such that at any instant, the 2 stars are on opposite sides of the centre of mass

what are visual binaries?

when many stars are in binary pairs, the measurement of their orbital motion allows determination of the masses of the stars, they can be measured directly

how can spectroscopic binaries be measured?

using their doppler shifts

how can eclipsing binaries be measured?

using the changes in luminosity as one star passes in front of the other

what is a nova?

A nova is a sudden, temporary brightening of a star caused by a nuclear explosion on the surface of a white dwarf in a binary system. It occurs when the white dwarf pulls in hydrogen from its companion star, leading to a burst of fusion that makes the star shine thousands of times brighter for a short time.

What happens when enough material falls onto a white dwarf from its main-sequence companion in a binary system?

material falls onto the white dwarf from its main-sequence companion, when enough material has accreted, fusion can reignite very suddenly, burning off new material and the material keeps being transferred to the white dwarf resulting in a Type I supernova.

what is a carbon-detonation supernova?

a white dwarf that has acculumated too much mass from its binary companion and once it exceeds 1.4 solar masses, electron-degeneracy can’t keep the core from collapsing resulting in a carbon explosion

what is the difference between a type I supernova and a type II supernova?

a type I supernova is a carbon-detonated supernova and a type ll supernova is the death of a high-mass star

What is the maximum luminosity a white dwarf can reach during an outburst, and how long can it last?

the maximum luminosity is that of a billion suns and it can last around 3+ months

Why do all Type-I supernovae reach the same maximum luminosity, and what causes them to occur?

because they originate from an exploding white dwarf when it reaches the mass limit of 1.4 solar masses and every type of type-l supernova reaches the same luminosity

how can type-l supernovas be considered as standard candles?

because a standard candle can be used to measure distance by measuring the apparent brightness and comparing it to actual brightness - they’re used as standard candles to measure distance

what is the fate of a low-mass star (<10 SM)

they never get hot enough for fusion past carbon to take place, they die smoothly with the outer envelop becoming a planetary nebula and the carbon core leaving a white dwarf with a mass up to 1.4 SM

what is the fate of a high mass star? (> 10 SM?)

it can continue to fuse elements in its core up to iron, then it dies with a big explosion called a supernova and turns into a type-ll supernova

What causes a nova to flare up suddenly on a white dwarf in a binary star system?

material falls onto the white dwarf and when enough material has been accumulated, fusion can reignite burning of the new material and it will create a nova that flares up suddenly

what is the fate of a white dwarf > 1.4 SM?

as the dwarf increases, it can’t withstand gravity and it stars to collapse, its temperature rises to where carbon can fuse into heavier elements causing carbon-detonation supernova or a type-l supernova because fusion began everywhere through the white dwarf