All nuclei are positively charged so for them to collide a very large electrostatic force must be overcome, which can done with a very high speed.
CloseWhen 2 objects are separated by 1 astronomical unit, at an angle of 1 arc second, then the distance to both objects is 1 parsec. \(1 \text{ parsec} = 3.26 \, \text{ly}\).
CloseBrightness is given by \( b=\frac{L}{4\pi d^2} \), so we can see if we triple the distance, b will decrease by a factor of 9.
CloseWhen we decrease the temperature the curve shifts down, reducing the power emitted (area under the curve), and the peak shifts to the right, increasing the average wavelength.
CloseTheir luminosity is about \(10^6\) times larger than the Sun's, and their radius \(1000\) times larger.
CloseSince the star is colder than the sun, it will be to the right of the sun. Additionally it has a radius similar to the sun, but a colder temperature, so its luminosity will also be smaller, so it will be under the Sun, hence we can deduce it will be in the bottom right quadrant.
CloseIn a stable star, the inward gravitational force pulling matter towards the core is balanced by the outward radiation pressure produced by fusion reactions. This balance prevents the star from collapsing under its own gravity or expanding uncontrollably.
CloseThe correct answer is: A.
Fusion in stars requires both high temperature and high density. High temperature gives the particles enough kinetic energy to overcome the electrostatic repulsion between them, while high density ensures that the particles collide frequently enough for fusion to occur.
CloseThe correct answer is: A.
Low-mass stars have lower core temperatures and burn their fuel more slowly than high-mass stars. As a result, they can last for billions of years, while high-mass stars burn fuel more quickly and have much shorter lifespans.
CloseStellar parallax involves measuring the apparent shift in a star's position when observed from two different points in Earth's orbit, typically six months apart. The angle of this shift can be used to calculate the star's distance using basic trigonometry.
CloseThe correct answer is: A.
Stars on the Main Sequence are in the phase of their lifecycle where they are primarily fusing hydrogen into helium in their cores. This includes stars of various luminosities and temperatures.
CloseLow-mass stars, after burning through their hydrogen, become red giants and eventually shed their outer layers, leaving behind a white dwarf. High-mass stars, on the other hand, undergo more dramatic changes, eventually leading to supernovae.
CloseThe correct answer is: B.
To determine the radius of a star, we commonly use the Stefan-Boltzmann law. This method relates the star's luminosity (\(L\)), temperature (\(T\)), and radius (\(R\)) through the formula:
\[ L = 4 \pi R^2 \sigma T^4 \]
Where \(L\) is the luminosity, \(R\) is the radius, \(\sigma\) is the Stefan-Boltzmann constant, and \(T\) is the temperature of the star. By knowing these values, we can determine the star’s radius accurately.
Close| Option | Necessary Conditions for Fusion |
|---|---|
| A | High density and high temperature are required for fusion to occur. |
| B | Low density and low temperature are sufficient for fusion reactions to take place. |
| C | Only a high temperature is needed to start fusion, regardless of density. |
| D | Fusion cannot occur in stars due to insufficient pressure. |
| Option | Effect of Stellar Mass on Evolution |
|---|---|
| A | Low-mass stars live longer and burn their fuel more slowly than high-mass stars. |
| B | High-mass stars live longer because they burn fuel more slowly than low-mass stars. |
| C | The mass of a star has no effect on its lifespan or the way it evolves. |
| D | Stars with masses below 1 solar mass cannot undergo fusion reactions. |
| Option | Region of the HR Diagram |
|---|---|
| A | The Main Sequence |
| B | The Red Giant Branch |
| C | The White Dwarf Region |
| D | The Supergiant Region |
| Option | Method for Determining Stellar Radius |
|---|---|
| A | Measuring the star's parallax angle. |
| B | Using the Stefan-Boltzmann law, based on the star's luminosity and temperature. |
| C | Determining the star’s mass using its gravitational effects on nearby objects. |
| D | Using spectroscopic data to measure the star's rotation speed. |