Space Physics Flashcards

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1
Q

Formation explained by accretion model

A
  • Gravity attracts particles in interstellar gas and dust clouds.
  • Clouds contain varied elements, with heavier ones closer to the center.
  • Material rotation forms accretion disc around central protostar.
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2
Q

Elliptical Orbits and Conservation of Energy

A
  • Objects in elliptical orbits around the Sun travel faster when closer to it.
  • This is explained by the conservation of energy principle.
  • As objects move closer to the Sun, their gravitational potential energy decreases, leading to an increase in kinetic energy and velocity.
  • Conversely, as objects move farther from the Sun, their gravitational potential energy increases, causing a decrease in kinetic energy and velocity.
  • This phenomenon demonstrates the balance between potential and kinetic energy to maintain a constant total energy in orbits.
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3
Q

Characteristics of Galaxies and Astronomical Distances

A
  • Galaxies comprise many billions of stars.
  • The Sun, our star, resides in the Milky Way galaxy.
  • Other stars within the Milky Way are much farther away from Earth than the Sun.
  • Astronomical distances are often measured in light-years, where one light-year represents the distance light travels in one year in the vacuum of space.
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4
Q

Definition:
Redshift

A

Redshift is the observed increase in the wavelength of electromagnetic radiation emitted from receding stars and galaxies.

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4
Q

Life Cycle of a Star

A
  • Stars form from interstellar clouds of gas and dust containing hydrogen.
  • A protostar forms when an interstellar cloud collapses, increasing in temperature due to gravitational attraction.
  • A protostar becomes a stable star when gravitational attraction balances the outward force from high internal temperature.
  • Stars eventually exhaust hydrogen fuel for nuclear reactions.
  • Most stars expand into red giants, while more massive stars become red supergiants after converting most hydrogen to helium.
  • Less massive stars form planetary nebulae with a white dwarf at their center after becoming red giants.
  • Red supergiants explode as supernovae, leaving behind nebulae containing hydrogen and new heavy elements, with a neutron star or black hole at the center.
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5
Q

Definition:
Cosmic Microwave Background Radiation (CMBR):

A

Microwave radiation of a specific frequency observed throughout space is known as cosmic microwave background radiation (CMBR).

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6
Q

Determining Galaxy Velocity (v):

A

The speed at which a galaxy moves away from Earth can be found from the change in wavelength of the galaxy’s starlight due to redshift.

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7
Q

Define:
Hubble Constant (H₀):

A

is defined as the ratio of the speed at which a galaxy is moving away from the Earth to its distance from the Earth.

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7
Q

Calculating Galaxy Distance (d)

A

The distance of a far galaxy can be determined using the brightness of a supernova in that galaxy.

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8
Q

Current Estimate for H₀:

A
  • The current estimate for H₀ is approximately 2.2 × 10^(-18) per second.
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9
Q

Equation:
Age of the Universe

A

d / v = 1 / H₀

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