Podcast
Questions and Answers
Who started the catalog of 'fuzzy objects' which helped distinguish them from comets?
Who started the catalog of 'fuzzy objects' which helped distinguish them from comets?
- Henrietta Swan Leavitt
- John Herschel
- William Parsons
- Charles Messier (correct)
The Andromeda Galaxy is referred to as M31.
The Andromeda Galaxy is referred to as M31.
True (A)
What type of variable stars are Cepheids?
What type of variable stars are Cepheids?
Radial pulsating stars
Henrietta Swan Leavitt discovered the Period-______ Law.
Henrietta Swan Leavitt discovered the Period-______ Law.
Match the following entities with their descriptions:
Match the following entities with their descriptions:
What was the primary function of the telescope known as the Leviathan of Parsonstown?
What was the primary function of the telescope known as the Leviathan of Parsonstown?
Cepheid variables have periods that range from 1 to 100 hours.
Cepheid variables have periods that range from 1 to 100 hours.
What significant discovery did Henrietta Swan Leavitt make?
What significant discovery did Henrietta Swan Leavitt make?
What is a characteristic feature of globular clusters?
What is a characteristic feature of globular clusters?
Globular clusters typically last only a few hundred thousand years.
Globular clusters typically last only a few hundred thousand years.
What did Edwin Hubble use to demonstrate the presence of Cepheid variables in spiral nebulae?
What did Edwin Hubble use to demonstrate the presence of Cepheid variables in spiral nebulae?
The distance to the spiral nebulae was determined using Leavitt's Law and the presence of __________.
The distance to the spiral nebulae was determined using Leavitt's Law and the presence of __________.
Match the following concepts with their descriptions:
Match the following concepts with their descriptions:
During the Great Debate, what were the two positions regarding spiral nebulae?
During the Great Debate, what were the two positions regarding spiral nebulae?
Galaxies evolved without any common origin or evolutionary ideas.
Galaxies evolved without any common origin or evolutionary ideas.
What did Hubble identify by studying the Doppler shift in galaxies?
What did Hubble identify by studying the Doppler shift in galaxies?
Flashcards
Galaxy
Galaxy
A large collection of stars, gas, dust, and dark matter held together by gravity.
Cepheid Variable
Cepheid Variable
A type of variable star that pulsates in brightness with a period directly related to its luminosity.
Period-Luminosity Law
Period-Luminosity Law
The relationship between a Cepheid variable's pulsation period and its intrinsic brightness, allowing astronomers to calculate distances.
Standard Candle
Standard Candle
A celestial object used to determine distances in space, such as Cepheids.
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Galactic Halo
Galactic Halo
The spherical halo of stars and dark matter surrounding a galaxy.
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Globular Cluster
Globular Cluster
A tightly packed cluster of hundreds of thousands, or even millions, of stars.
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Galactic Bulge
Galactic Bulge
The central bulge of a spiral galaxy, containing older stars and a supermassive black hole.
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Galactic Disk
Galactic Disk
The flat, rotating disk of a spiral galaxy, containing younger stars, gas, and dust.
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Redshift
Redshift
The measurement of the change in wavelength of light emitted by a distant object due to its motion.
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Hubble's Law
Hubble's Law
A law that states that galaxies are moving away from each other at a speed proportional to their distance apart.
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Galaxy Phylogenetics
Galaxy Phylogenetics
The study of the history and evolution of galaxies.
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The Great Debate
The Great Debate
The debate about the nature of spiral nebulae, whether they were distant galaxies or nearby nebulae within the Milky Way.
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Hooker Telescope
Hooker Telescope
The telescope that Edwin Hubble used to observe Cepheid variables in distant galaxies, providing evidence they were independent of the Milky Way.
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Astrophysical Concepts
- PH222 is an astrophysical concepts course taught by Aaron Golden at the University of Galway.
- The course covers topics such as gravity, galaxies, and their evolution.
Gravity IV
- This section of the course is focused on gravity.
Stars and Giant Planets
- This topic discusses stars (and giant planets).
Expanding Horizons
- The presenter suggests expanding the current understanding beyond previously explored topics.
Andromeda Galaxy (M31)
- A spiral galaxy.
- Information about M31 as an astrophysical object.
Galaxies Before 1845
- Charles Messier, a key figure in astronomy, compiled a catalog of diffuse astronomical objects.
- This catalog helped astronomers distinguish between fuzzy and point source objects.
Modern Telescopes
- The course discusses advanced telescopes, like the HST and JWST, and their impact on astronomical discoveries.
- Details regarding the size of early telescopes, like the Leviathan of Parsonstown, and William Parson’s measurements.
M51
- M51 is an important target for astronomical observations.
- Details on William Parsons' observations and analysis.
- The resolution of the telescope and its optics are significant developments.
Galactic Anatomy
- The Milky Way is classified as a spiral galaxy.
- Composed of parts like the nuclear bulge, disk, and halo.
- Dimensions are discussed in kiloparsecs (kpc).
- Contains stars and a supermassive black hole.
Galactic Halos
- Discussion of globular clusters.
- Globular clusters are composed of stars and have an age greater than billions of years.
- They possess a spherical and regular shape, tightly bound.
Galaxy Types
- Spiral galaxies (roughly 30%): Examples include the Milky Way and Andromeda, often with a central bar structure.
- Elliptical (about 50%): M87 is a prominent example. Characterized by a lack of gas, dust, and the ability to form new stars.
- Irregular (around 20%): Lack structural regularity.
Interlude 3
- The universe contains many galaxies.
- Ideas about the evolution of galaxies are touched upon.
Hubble's Law
- A relationship exists between the distance and the rate of recession of remote galaxies.
- The Hubble constant has a value of (67.80 ± 0.77) km s−1 Mpc−1.
Quasars
- Quasars (3C 273) are subjects of study.
- Calculations for distance (in Mpc) and redshift (z) are included.
- These calculations apply to the specific case of the quasar 3C 273.
Wrap Up
- The history of the universe and its astronomical observations are mentioned.
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