Tau.Neutrino said:
What Telescope Will Be Needed to See the First Stars in the Universe? The Ultimately Large Telescope
The oldest stars in the Universe are cloaked in darkness. Their redshift is so high, we can only wonder about them. The James Webb Space Telescope will be our most effective telescope for observing the very early Universe, and should observe out to z = 15. But even it has limitations.
more…
> The title of the new paper is “The Ultimately Large Telescope – what kind of facility do we need to detect Population III stars?” Lead author is Anna Schauer, a Research Affiliate in the Department of Astronomy at the University of Texas, Austin. The paper is available at the pre-press site arxiv.org.
Unless, of course, population III stars don’t exist, which is possible if they have life-spans so short … OK, I’m being Devil’s advocate here.
> Scientists theorize that most of these Pop 3 stars exploded as pair-instability supernovae. In this terminology, “pair” doesn’t mean binary pair. It describes the production of pairs of electrons and positrons in the star, that leads to the collapse of the star, then the runaway thermonuclear explosion of the star when it goes supernova.
I’ve think I’ve heard of pair-instability supernovae before. Isn’t this where iron degrades back into smaller particles (alpha particles?) before explosion? I could be wrong here. Wikipedia gives this diagram.
> The ULT would need to have a 100 meter mirror. That’s absolutely enormous, considering that the largest optical telescope under construction now—the European Extremely Large Telescope (EELT)—will have a 39.3 meter mirror.
> According to the authors, this monstrosity would have to be built on the Moon.
Um, what!
Perhaps I’m showing my age here, but a 100 metre telescope on Earth is roughly equivalent to a 15 metre telescope on the Moon. Which is 2.3 times the diameter of the James Webb. Something that size could perhaps be done, but not 100 metre on the Moon.
What field of view are we talking about here? Unstated, but of the order of a square arcminute. By way of comparison, the JWST field of view is of the order of 10 arcminutes.
> Brown Dwarfs: Due to their red colour, brown dwarfs are a common contaminant for high-redshift sources.
Huh. I’d call finding brown dwarfs a main aim. Small brown dwarfs are free planets – in our galaxy.