10 Solar Astronomy Flashcards
How can you safely observe the Sun?
- Pinhole projection
- H-alpha filter
- Telescopic projection
What are sunspots?
Sunspots are cooler areas of the Photosphere where the Sun’s magnetic field rises from below the Sun’s surface and the magnetic regions poke through. They are darker in colour as they are expending less energy and have a lower temperature
What is the average temperature of a Sunspot?
Umbra is ~3800K
Penumbra is ~5600K
How can you calculate solar rotation period?
If the difference in longitude (ΔL) of a sunspot occurs in a time interval, then rotation period (T) can be calculated by:
T . . 360°
—- = ——
Δt . . ΔL
What is the earliest Nuclear Fusion?
The earliest Nuclear Fusion is when hydrogen (H) nuclei fuse into Helium (He) nuclei.
Why can Nuclear Fusion only happen in the Sun’s core?
The temperature has to be high enough to overcome the mutual electrostatic repulsion of the positively-charged nuclei
What is the chain of reaction that happens in the Sun?
The Proton-Proton or Deuterium-Deuterium chain
What happens in each stage in the proton-proton chain?
At each stage in the chain, mass (m) is lost and converted into energy (E). This is in accordance with Einstein’s equation E=mc², where c is the speed of light
How much mass does the Sun lose?
The Sun loses 4 million tonnes of mass every second, this is insignificant as the Sun’s total mass is 2.0 × 10²⁷ tonnes
What is the zone above the Sun’s core?
Radiative zone
What happens in the radiative zone?
This zone is where the energy in the form of photons (gamma-radiation) is transferred in a random manner due to the scattering of photons by electrons outwards
What is the zone outside the radiative zone?
The convection zone
How thick is the convection zone?
~200 000 km
What happens in the convection zone?
The convection zone is where the thermal energy is transported to the photosphere by rising convection currents of hot plasma.
What is at the top of the convection zone?
The photosphere
How hot is the photosphere?
The photosphere is ~2 million K at the base. At the visible part of the photosphere, the temperature is 5800 K
How thick is the photosphere?
100 km
How does the Sun radiate energy?
The Sun radiates energy in the form of visible light but also to a lesser extent of infra-red, ultra-violet and X-Radiation
What are the parts of the Sun’s atmosphere?
The chromosphere and corona
How thick is the chromosphere?
2000 km thick
How hot is the chromosphere?
400 K - 100 000 K at the top
How hot is the corona?
2 million K
How far can the corona extend?
The corona can extend outwards for millions of km into space
What is ‘slow’ solar wind?
An outflow of charged particles (mostly protons and electrons)
Where does ‘slow’ solar wind come from?
The Corona
What is the speed of ‘slow’ solar wind?
~400 km/s
Where does ‘fast’ solar wind originate from?
Coronal holes
What is ‘fast’ solar wind associated with?
Coronal mass ejections and Solar Flares
What is solar wind responsible for?
Solar wind is responsible for aurora and the creation of cometary tails
What is the Butterfly Diagram?
The butterfly diagram is a diagram that shows the solar cycle of sunspots. The cycle begins with a few spots at mid latitude. The numbers of sunspots fall and rises, and they drift towards the solar equator
How long does the solar cycle last?
11 years
What is a Type II Supernova?
A Red Supergiant collapses
What is a Type Ia Supernova?
A Type Ia Supernova occurs when Red Giant star is in a binary system with a white dwarf. Over time, the white dwarf will gravitationally steal matter from the Red Giant, resulting in the increase of mass. It will surpass the Chandrasekhar limit and the electron degeneracy pressure will be insignificant in preventing the collapse, resulting in a supernova
What stage of a star does a planetary nebula represent?
Death
What is Fast solar wind?
A build up of of magnetic energy which is released from a sunspot
What is slow solar wind?
Particles that are emitted from all over the Sun.
They are slowed by the magnetic fields of the Sun
They are mostly charged protons and electrons
When is there more fast solar wind?
During the middle of a Sunspot cycle where there are the most amount of Sunspots
Why does Nuclear fusion only take place in the Sun’s core?
The particles need to be hot enough to withstand the electric repulsive forces. They have to hit each other fast so they need to be at very high pressure (15 Million Kelvin)
What are sunspots?
Sunspots are black spots on the surface of the Sun that are formed where the the magnetic field leaves the surface. It is a cool area where no convection occurs
What prevents the ionising rays from reaching the surface of the Earth?
Magnetosphere
What is the equation that tells you how to find longitude in the UK?
Local Mean Time - Mean Solar Time In Greenwich
_______________________________________
. . . . . . . . . . . . . . . . . . . . . . . 4
=Degrees of Longitude to the East
What is the First Umbral Contact for a solar eclipse?
The First Umbral Contact is when the Moon starts to cover the Sun
What is the Second Umbral Contact for a solar eclipse?
The second Umbral contact is when the Moon has just finished covering the Sun
What is the Third Umbral contact for a solar eclipse?
The Moon is on the cusp of leaving the Umbra of the Sun
What is the Fourth Umbral Contact for a solar eclipse?
The fourth Umbral Contact is when the Moon has just left the Sun
What is an Annular solar eclipse?
When the Moon is too small to fully cover the Sun so a ring of light surround the Sun
Why does an Annular Solar eclipse occur?
An Annual Solar Eclipse occurs when the Moon’s orbit is in an apogee and the the Moon appears to small to cover the entire Sun compared to normal eclipses.
What is an accretion disk?
An accretion disk consists of hot, swirling gas captured by a white dwarf ( or neutron star or black hole ) from a binary companion star.
When can white dwarf supernova occur?
A white dwarf supernova can occur only in a binary system, and all such events are thought to have the same luminosity.
What are the Sun’s internal divisions in order?
Photosphere
Convective zone
Radiative zone
Core
How does a H-alpha filter make the observation of the Sun safe?
A H-alpha filter makes the observation of the Sun safe as the intensity of light received from the Sun is reduced
Where does the Sun rotate faster?
The Sun rotates faster at the equator then the poles
How hot is the Corona?
2 million K
How hot is the Core of the Sun?
15 million K
How hot is the photosphere?
5800 K
How hot is the top of the Chromosphere?
100 000 K
How hot is a typical Sunspot Umbra?
3800 K
How hot is a typical Sunspot Penumbra?
5600 K
