Astronomy MASTER STUDY GUIDE #2 - Semester 2

Which is the best definition for a nova?

A star that flares up very suddenly and then returns to its former luminosity

A high mass star can fuse elements up to about ______ in its core.

iron

At the end of a high mass star’s life, inward pressure becomes so great that neutrons are compressed so greatly, and a giant explosion called a ______ is observed.

supernova

When comparing brightness, a supernova can be ___ brighter than a nova.

1,000,000x’s (a million times)

The two types of supernovae are:

high mass and carbon detonation

Supernovae are rare. There has not been one in our galaxy for about ___ years.

400

On Earth, there are ___ stable elements that came from star formation.

81

On Earth, there are 10 ______ elements that came from star formation.

radioactive

After a Type II supernova, part of the core may survive. It is very dense — as dense as an atomic nucleus — and is called a:

neutron star

A very rapidly spinning version of the object described in question 9 (neutron star) is known as a:

pulsar

Why are the objects described in question 10 (pulsars) nearly impossible to detect?

They don’t last long, and their jets have to be pointing at the Earth.

Most pulsars have a period of about ___ seconds.

0.03-0.3

The newest class of pulsars discovered more recently is called the:

millisecond pulsars

The most likely reason that the newest type of pulsar exists is because they are being:

Spun up by in-falling matter

Gamma-ray bursts were first stumbled upon by:

Satellites looking for violations of nuclear test-ban treaties

Because no clumping of radiation was detected, it is inferred that gamma-ray bursts must occur:

Outside of our galaxy

How can distance to gamma-ray bursts be measured?

Using the Spectrum

Two models (probably both correct) have been proposed as the source for gamma-ray bursts. They are:

merging neutron stars or a hypernova

The longer gamma-ray bursts are most likely produced by:

supernovae

The Schwarzschild radius is defined as:

The radius at which the escape speed from the black hole equals the speed of light

Once the black hole has collapsed, the Schwarzschild radius takes on a new name, called the:

event horizon

What is true of the location described in question 21 (event horizon)?

Nothing can escape the black hole within this area.

Which of the following is NOT part of the theory of Special Relativity?

There is absolutely no difference in acceleration or direction for the observer.

A black hole occurs when the “indentation” caused by the mass of the hole becomes:

infinitely deep

Matter encountering a black hole begins to experience enormous:

tidal forces

What is inside of a black hole?

No one knows; it remains a mystery.

Which is considered a strong black hole candidate?

Cygnus X-1

The centers of many galaxies contain ______ that total about ___ solar masses.

Supermassive black holes; 1 million

Intermediate mass black holes, though not well-understood, are believed to have ___ solar masses.

100-1,000

Two ways the theory of relativity was tested involved analyzing:

Solar Eclipse of 1919 and Mercury’s orbit

The shape of the Milky Way Galaxy is best believed to be a:

spiral

One of the first attempts at mapping our galaxy was done by:

Herschel

The two types of intrinsic variables that have been found are:

RR Lyrae stars and Cepheids

A Cepheid variable star has a period of about ___ days.

1-100

Much of the early work in astronomy was done by analyzing photographs by computers, which at the time were:

Actually groups of women

Where are the youngest stars located in the Milky Way Galaxy?

galactic disk

This area of the Milky Way contains very old stars and no gas or dust:

halo

What is the current estimate for the length of one galactic year?

225-250 million years

The orbital speed of an object depends only on the amount of ______ between it and the galactic center.

mass

Low-mass white dwarfs could account for as much as ___ of the mass needed to explain dark matter.

20%

Which is NOT true of our galactic center?

Its location is not known.

The innermost star of the Milky Way Galaxy is called:

S-2

Spiral galaxies are classified according to the size of:

Their central bulge

Hubble classified galaxies as:

Sa, Sb, Sc (with Sc being smallest)

Which of the following is NOT a component of a spiral galaxy?

rim

We know that elliptical galaxies have:

No spiral arms and no disk

Elliptical galaxies are classified from:

E0-E7

A popular schematic used in galactic classifications is:

Hubble’s tuning fork

Correlating a galaxy’s rotation speed with its luminosity is done with the:

Tully-Fisher relation

What can be used as “standard candles?”

Type I supernovae