Hubble's Discovery of Cepheid Variable Stars in Galaxies

In summary, Hubble was able to determine the distance to galaxies by using Cepheid variable stars as "standard candles." These stars are bright and have a predictable period, making them useful for measuring distances. With the help of modern instruments, Cepheids can now be detected up to 60 million light years away. Hubble's discovery of other galaxies aside from the Milky Way was groundbreaking and continues to be an area of research.
  • #1
Holocene
237
0
Cepheid variable star?

How was Hubble able to determine that one of these stars was within what was then called a nebula?

You're telling me that back in the early 1900's, he was able to detect a single star within a distant galaxy?
 
Astronomy news on Phys.org
  • #2
A supernova explosion is so bright that it can outshine entire galaxy. Not only that, it can shine for a couple of weeks before dimming. That can give an astronomer plenty of time to find it in the sky and analyze it.
 
  • #3
Didn't Hubble use Cepheids, and not supernovas, to deduce the distance to galaxies?
 
  • #4
Well, since Cepheids are variable stars, some of them are very big and get very bright, which yes, was visible with telescopes in the early 1900's. I imagine that after noticing the predictable period, he discerned it was a Cepheid and was able to use it as a "standard candle"
 
  • #5
Here are a couple of links that show images that Hubble used:
http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/galaxies.htm"
http://www.ottawa.rasc.ca/features/marchHubble/index.html"
 
Last edited by a moderator:
  • #6
matt.o said:
Here are a couple of links that show images that Hubble used:
http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/galaxies.htm"
http://www.ottawa.rasc.ca/features/marchHubble/index.html"

Great links, thanks.
 
Last edited by a moderator:
  • #7
Hubble made an amazing discovery with relatively weak instruments - that other galaxies aside from the MW exist. Cepheids in the Andromeda galaxy [at a distance of about 3 million light years] were near the limit of detectability by instruments available to Hubble in the early 20th century. Modern instruments can detect cepheids out to around 60 million light years. It's still an exciting area of research. Studies indicate metallicity is an important variable in the absolute luminosity of Cepheids. Other distance indicators have helped calibrate Cepheid derived distances.
 

1. What is Hubble's discovery of Cepheid Variable Stars in Galaxies?

Hubble's discovery of Cepheid Variable Stars in Galaxies was a groundbreaking observation made by astronomer Edwin Hubble in the 1920s. He found that certain stars, called Cepheid variables, varied in brightness over time and that this variability could be used to measure the distances to galaxies. This discovery revolutionized our understanding of the size and scale of the universe.

2. How do Cepheid variables help us measure the distances to galaxies?

Cepheid variables are stars that pulsate in a regular pattern, with their brightness increasing and decreasing over time. The rate of this pulsation is directly related to the star's intrinsic brightness, so by measuring the period of the pulsations, we can determine the star's true brightness. By comparing this to the apparent brightness of the star, we can calculate its distance from us. This method, known as the period-luminosity relationship, has been used to measure the distances to thousands of galaxies.

3. Why was Hubble's discovery of Cepheid variables significant?

Hubble's discovery of Cepheid variables was significant because it provided a reliable and accurate way to measure the distances to galaxies. Before this, astronomers had no way of knowing how far away these objects were, and as a result, had no understanding of the true size and scale of the universe. With this discovery, Hubble was able to confirm that the universe is much larger than previously thought, with billions of galaxies spread across vast distances.

4. What impact did Hubble's discovery have on our understanding of the universe?

Hubble's discovery of Cepheid variables had a profound impact on our understanding of the universe. It confirmed that the universe is much larger than previously thought, and that it is expanding. This discovery also helped to establish the concept of a "Big Bang" origin for the universe, as well as the idea of an expanding universe, which has become a cornerstone of modern cosmology.

5. How does Hubble's discovery continue to impact our understanding of the universe today?

Hubble's discovery of Cepheid variables continues to have a significant impact on our understanding of the universe today. The period-luminosity relationship has been refined and expanded upon, allowing us to measure even greater distances to galaxies and gain a better understanding of the structure and evolution of the universe. This discovery also paved the way for future space missions, such as the Hubble Space Telescope, which continues to provide us with invaluable insights into the cosmos.

Similar threads

Stargazing Hubble Spots Farthest Star Ever Seen
    • Astronomy and Astrophysics
Replies
9
Views
1K
B Vulpecula, pulsars and neutron stars
    • Astronomy and Astrophysics
Replies
10
Views
1K
B Questions about Supermassive stars in the Milky Way Galaxy
    • Astronomy and Astrophysics
Replies
6
Views
2K
I SN 2019hgp, new type of supernova? Wolf-Rayet progenitor?
    • Astronomy and Astrophysics
Replies
1
Views
850
Stargazing How do we know how bright a cepheid variable star is?
    • Astronomy and Astrophysics
Replies
5
Views
2K
I Questions on stars and planets: ratio of planet radius to star, distance between the two, temperature of a star and a planet, planet rotation speed
    • Astronomy and Astrophysics
Replies
12
Views
1K
Stargazing Is There an Unidentified Object Near the Horsehead Nebula?
    • Astronomy and Astrophysics
Replies
14
Views
509
B Trying to understand the differences between distant & local galaxies
    • Astronomy and Astrophysics
Replies
5
Views
1K
I Challenges to the Redshift Method and Hubble's Law
    • Astronomy and Astrophysics
Replies
5
Views
2K
B Why most stars seem to rotate the same direction in a galaxy?
    • Astronomy and Astrophysics
Replies
6
Views
2K

Hot Threads

Recent Insights

Back
Top