Module 3: Formation of Stars and Planets

Question 1

Composition of the Universe

Answer 1

Dark Energy, Dark Matter, (Visible) Matter

Question 2

Cosmic Microwave Background

Answer 2

Validates the composition of the universe

Question 3

CMB Analyser

Answer 3

shows the energy signature varies as some of the more important input parameters of our universe are modified

composition of the universe:
Atoms
(Cold) Dark Matter
Dark Energy

Hubble constant
Reionization Redshift
Spectral Index

Question 4

Hubble Constant

Answer 4

indicates how fast the universe is currently expanding (in units of kilometres per sec per Megaparsec).

It is a measure of how fast an object is moving away from us based upon its distance from the Earth today.

Question 5

Reionization Redshift

Answer 5

The era when the first stars formed, expressed in redshift units.

The radiation produced by the first stars stripped electrons off hydrogen atoms in the surrounding gas.

Question 6

Spectral Index

Answer 6

Describes the initial density ripples in the universe.

A smaller spectral index means the ripples with longer wavelengths are stronger and with shorter wavelengths weaker.

Question 7

% composition of the universe

Answer 7

Atoms: 4%
Cold Dark Matter: 22%
Dark Energy: 74%

Hubble Constant: 73
Reionization Redshift: 11
Spectral Index: 0.95

Question 8

What could be one of the reasons why there is an uneven distribution of matter?

Answer 8

clue: Influence of one of the fundamental forces

Question 9

Stellar Evolution

Answer 9

A description of the way that stars change with time.

The primary factor determining how the star evolves is its mass as it reaches the main sequence.

Question 10

Hertzsprung-Rusell Diagram

Answer 10

the most important tools in the study of stellar evolution.

1900s

Ejnar Hertzsprung and Henry Norris Russell

it plots the temperature of star against their luminosity

Question 11

Low-mass Stars

Answer 11

<8 solar masses

Question 12

High-mass stars

Answer 12

> 8 solar masses

Question 13

(Solar) Nebular Hypothesis

Answer 13

formation of our solar system

1. Large bodies in the solar system have orderly motions.
2. There are two types of planets: terrestrial and Jovian planets
3. Asteroids and comets ecist in certain regions of the solar system
4. Notable exceptions to these trends stand out( unusual rotation axis tilts, large moons, unusual orbits)

Question 14

Terrestrial Planets

Answer 14

smaller size and mass
higher density
solid surface
few moons and rings
closer to the sun

Mercury, Venus, Earth, Mars

Question 15

Jovian Planets

Answer 15

large size and mass
lower density (H and He)
no solid surface
rings and many moons
farther to the sun

Jupiter, Saturn, Uranus, Neptune

Question 16

Two Principle in Nebular Theory

Answer 16

1. Newton’s Law of Gravity (Gravitational potential energy ➡️heat)
2. Conservation of Angular Momentum (rotational motion is conserved)

Question 17

Solar Nebula

Answer 17

Is the cloud of gas from which our own Solar System formed.

Question 18

Formation of Planets

Answer 18

1. Cloud Collapse
2. Formation of Protoplanetary disk
3. Growth of planets

evidences of the nebular theory were observed through cosmic event in the neighboring galactic nebula, M16

Question 19

Why Pluto is no longer considered as a planet

Answer 19

three criteria waits

Question 20

It is a type of matter which does not interact with the electromagnetic force. This means that it does not absorb, reflect, or emit light, making it extremely hard to detect.

Answer 20

Dark Matter

Question 21

What percentage of visible matter (the matter we know that makes up all stars and galaxies) is present in the universe?

Answer 21

5%

Question 22

What percentage is the composition of dark matter in the whole universe?

Answer 22

27%

Question 23

It is the very first generation of stars which do not have any metal at all.

Answer 23

Population III stars

Question 24

These are old, metal-poor stars.

Answer 24

Population II stars

Question 25

These are stars rich in atoms heavier than helium; nearly always a relatively young star found in the disk of the galaxy.

Answer 25

Population I stars

Question 26

This is the minimum mass that a clump of gas must have to collapse under its gravity which is proportional to the square of the gas temperature and inversely proportional to the square root of the gas pressure.

Answer 26

Jeans mass

Question 27

It is defined by the Oxford English Dictionary as a state of “violent commotion, agitation, or disturbance,” with a turbulent fluid further defined as one “in which the velocity at any point fluctuates irregularly.” It plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions.

Answer 27

Turbulence

Question 28

This hypothesis posits that a giant cloud of molecular gas and dust underwent gravitational collapse, possibly due to shock waves from a nearby supernova explosion. Pockets of dust and gas began to collect into denser regions. As the denser regions pulled in more and more matter, conservation of momentum caused it to begin rotating, while increasing pressure caused it to heat up. Most of the material ended up in a ball at the center while the rest of the matter flattened out into a disk that circled around it. While the ball at the center formed the Sun, the rest of the material would form into the protoplanetary disk.

Answer 28

Nebular hypothesis

Question 29

The formation of the planets is believed to follow a sequence of these steps.

Answer 29

1. Gravitational collapse
2. From dust to planetisimals
3. From planetisimals to protoplanets
4. From protoplanets to giant planets
5. From protoplanets to terrestrial planets
6. Orbital migration

Question 30

These planets include Mercury, Venus, Earth, and Mars — are closer to the Sun and they consist of a core composed mostly of iron, a mantle composed of rock (mostly silicates), and an atmosphere whose mass is a negligible fraction of the total mass of the planet.

Answer 30

Terrestrial planets

Question 31

These planets include Jupiter and Saturn are 300 and 100 times more massive than the Earth, respectively, and are mostly composed of a mixture of hydrogen and helium in the same proportion as is found in the Sun.

Answer 31

Gas giants

Question 32

These planets include Uranus and Neptune are at the outer edge of the solar system, are roughly 15 times more massive than the Earth, and are composed of roughly equal parts each of rock, ice, and a hydrogen-helium mix.

Answer 32

Ice giants

Question 33

What are the different categories of exoplanets seen so far?

Answer 33

▪ Hot Jupiters
▪ Giant planets with eccentric orbits
▪ Super-Earths

Question 34

These exoplanets are Jupiter-like planets orbiting very close to their stars with periods of only a few days.

Answer 34

Hot Jupiters

Question 35

These exoplanets are generally found in compact systems of two to four planets each, orbiting their stars at distances from 0.006 to 1 au in periods ranging from more than 100 days down to hours. Although there are no super-Earths in our Solar System, they orbit at least 40% of all nearby Sun-like stars, which makes them the most common type of planet found.

Answer 35

Super-Earths