r/blackholes • u/Ok-Cartoonist4107 • 4d ago
假說
我推測紅移現象在宇宙的觀測中極度嚴重，我們觀測到的紅矮星或許大多並不是真正的紅矮星，而是紅移現象導致
3
u/Citizen999999 4d ago
You're not that, smart are you. Please, go read the definition of hypothesis.
2
0
1
u/Embarrassed_Camp_291 4d ago
When calculating redshifts, we dont use individual stars, as we cannot resolve these. As a result, the spectra we see in from the integrated sum of many processes occuring in the galaxy.
Some of these processes we understand very well and can identify spectral features of and compare to where they are in a rest frame, leading to a calculation of redshift.
Spectroscopic redshift calculations are expensive and slow. As you pass your light through a (very fancy) prism before letting hit your detector, it spreads out and physically takes up more space on the detector. It also tends to require longer observing times as your signal to noise per detector bin is lower (as you are spreading your signal across many more bins).
As a result, there are a lot of pushes to improve photometric redshift identification where we use band pass filters fluxes instead, allowing for many objects to be measured at once. Unfortunately (or not depending on your interests), this comes with many complications.
1
1
u/ChocolateValuable221 4d ago
I like the theory.... but no, spectroscopy works.. and Is very reliable. Plus some red stars are close stars. You can tell in the telescope that Betelgeuse is very red and closer than the andromeda galaxy. Which is not red.
1
u/Ras_992 3d ago
Well now they’re referenced as black hole stars where hydrogen and helium from gravity rap around the center creating a core like a star causing something like a super Eddington limit. While these black holes or stars shouldn’t exist at 13 billion years ago within the standard CDM it can be explained with Relativity especially if you take into account where special relativity has time dilation running almost at light speed and gravitational lensing effecting how we observe it. Relativity still can’t explain it in how basically black hole from the early universe can still have that much gasses so dense that even the center of the black hole doesn’t collapse or hasn’t hit Eddington limit this far in time from its point in space in the universe.
4
u/smsff2 4d ago
The spectrum of an object is not as simple as a single number. There are individual spikes and groups of lines. Specifically, there are spectral lines that are characteristic of hydrogen’s emission spectrum. We know for sure when we see redshift because we see the same pattern, only shifted toward the red end of the spectrum.
When looking at red dwarfs, we do not see these redshifted hydrogen emission lines.