U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Science and Technology > Space
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
 
Old 09-20-2012, 01:24 PM
 
Location: Texas
5,070 posts, read 9,076,032 times
Reputation: 1632

Advertisements

Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Way's mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.[LEFT]
Read more here: NASA Telescopes Spy Ultra-Distant Galaxy Amidst Cosmic 'Dark Ages' - PR Newswire - The Sacramento Bee
[/LEFT]
Reply With Quote Quick reply to this message

 
Old 09-21-2012, 10:38 AM
 
Location: Wasilla, Alaska
17,825 posts, read 20,496,555 times
Reputation: 6500
I have a couple of issues with the article. First and foremost is using gravitational lensing to measure redshift. Gravitational lensing distorts the light, and therefore distorts the spectrum. Redshift, on its own, is not a good measure of distance. A much better "standard candle," especially for vast distances, are type 1a supernovas. We know the absolute magnitude of all type 1a supernovas. By viewing the type 1a supernova in the visible spectrum we can determine its apparent magnitude. With both the absolute and apparent magnitudes we can calculate distance. Combined with an analysis of the spectrum we get a much better idea of its distance.

Second, they did not mention the name of the galaxy in the article. However, upon further research I believe the galaxy is called "MACS1149-JD1," but if that is the case then this discovery was made in April 2012, not September as the article implies.

Lastly, the article states that "[t]he first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron, a state that the gas has remained in since that time." The very first luminous stars would have formed before galaxy formation, about 30 million years after the Big Bang. Galaxies formed around 300 million years after the Big Bang.

Originally they estimated the Epoch of Reionization lasted about one billion years, but recent findings suggest that it may have only taken about 500 million years to reach the ~10% opacity that we see today as a result of ULIRGs.

The article below says that MACS1149-JD1 was discovered using "a Hubble survey called CLASH (Cluster Lensing and Supernova Survey with Hubble) to find the lensing cluster, MACS1149" because the object is too distant to be seen by Hubble in the visible spectrum.

Source:
Infant galaxy offers tantalizing peek at early Universe : Nature News & Comment

Last edited by Glitch; 09-21-2012 at 10:49 AM..
Reply With Quote Quick reply to this message
 
Old 09-25-2012, 12:37 AM
 
Location: Texas
5,070 posts, read 9,076,032 times
Reputation: 1632
Quote:
Originally Posted by Glitch View Post
I have a couple of issues with the article. First and foremost is using gravitational lensing to measure redshift. Gravitational lensing distorts the light, and therefore distorts the spectrum. Redshift, on its own, is not a good measure of distance. A much better "standard candle," especially for vast distances, are type 1a supernovas. We know the absolute magnitude of all type 1a supernovas. By viewing the type 1a supernova in the visible spectrum we can determine its apparent magnitude. With both the absolute and apparent magnitudes we can calculate distance. Combined with an analysis of the spectrum we get a much better idea of its distance.

Second, they did not mention the name of the galaxy in the article. However, upon further research I believe the galaxy is called "MACS1149-JD1," but if that is the case then this discovery was made in April 2012, not September as the article implies.

Lastly, the article states that "[t]he first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the universe to ionize, or lose an electron, a state that the gas has remained in since that time." The very first luminous stars would have formed before galaxy formation, about 30 million years after the Big Bang. Galaxies formed around 300 million years after the Big Bang.

Originally they estimated the Epoch of Reionization lasted about one billion years, but recent findings suggest that it may have only taken about 500 million years to reach the ~10% opacity that we see today as a result of ULIRGs.

The article below says that MACS1149-JD1 was discovered using "a Hubble survey called CLASH (Cluster Lensing and Supernova Survey with Hubble) to find the lensing cluster, MACS1149" because the object is too distant to be seen by Hubble in the visible spectrum.

Source:
Infant galaxy offers tantalizing peek at early Universe : Nature News & Comment
I took a few minutes to pass on your note to see if there is a reply from zheng@pha.jhu.edu, Wei Zheng at Johns Hopkins.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:

Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Science and Technology > Space
Follow City-Data.com founder on our Forum or

All times are GMT -6. The time now is 11:55 AM.

© 2005-2019, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 - Top