Questions tagged [age]
Questions about the temporal duration of a celestrial object.
47 questions
0
votes
0
answers
85
views
Could the huge mass density in the very early universe have caused gravitational time dilation that delayed light and makes the universe look younger?
I'm wondering if this could explain the galaxies that appear to be older than is possible.
Webb found these six bright, red, extremely distant galaxies that appear to be too massive to exist that ...
8
votes
1
answer
2k
views
What would evidence of stars and galaxies significantly older than 13.8 billion years old look like? In what parts of space has it not been found?
The September 19, 2023 podcast with transcript Why the earliest galaxies are sparking drama and controversy among astronomers includes the following:
An article published earlier this year in the ...
- 30.7k
-2
votes
3
answers
2k
views
Why is Earth 1/3 the age of the universe?
The Earth is 4.6 billion years old
The universe is 13.8 billion years old.
3 times the age of the Earth
Are there other planets with ages that are close to say 1/4 1/5 etc the age of the universe? Why ...
user48394
3
votes
0
answers
85
views
Cosmic microwave background the same as the first visible light at 379,000 yrs after the Big Bang? How do these measure the age of the universe?
Was the CMB emitted at the same time as visible light at 379,000 yrs after the BB ? Was this a one time event ? If headed away from us, how does it measure the age of the universe?
- 31
3
votes
1
answer
566
views
What is mass-weighted age?
This seems to be a common term used in the field of stellar populations and galaxy evolution, but I can't find a good definition besides the fact that it is different from light-weighted age (a term I ...
5
votes
1
answer
413
views
Does "Angular Diameter Turnaround Point" solve the Great Wall Problem?
According to Wikipedia,
The Hercules–Corona Borealis Great Wall is the largest known structure in the observable universe, measuring approximately 10 billion light-years in length.
But since it's ...
42
votes
3
answers
7k
views
How did Hubble know the red shift difference between "moving away" and "old"?
My 9yo daughter is very into space at the moment and asked a question that my physics knowledge (6th form college, 20 years ago) is way too poor to answer.
Her space book tells us that as stars age, ...
- 521
1
vote
2
answers
297
views
How slow would you age on a double gravity planet?
How slow would you age on a double gravity planet?
Gravity of the planet A is 10 units. If you are taken from planet A to planet B where gravity is double that of A, i.e. 20 units. How slowly would ...
- 1,007
1
vote
2
answers
155
views
Do black holes have "age" when they form?
I was thinking about black holes, and I know that they form by the death of massive stars. I was wondering, though, do they technically have an "age" when they're born? Do they begin at 0 ...
- 655
1
vote
1
answer
122
views
Why is there a discrepancy with calculated and given age of nebula
In the book "Horizons: exploring the universe-Cengage learning (2018)", page 206, it states that:
Simple observations tell astronomers about the nature of planetary nebulae. Their angular ...
- 1,306
0
votes
2
answers
152
views
Seeming conflict between most distant objects and age of universe (both estimated)
There was a recent article on bbc.com for laypeople like me titled "The mystery of how big our Universe really is", which prompted me to post the following question in their comments section ...
4
votes
1
answer
71
views
Long-lived supernova remnants?
We cannot see the supernova remnant of the star that triggered the formation of the Sun and the Solar System, as the remnant dispersed and became mixed into the interstellar medium. So I am wondering, ...
- 6,733
6
votes
2
answers
624
views
How to determine the age of a star using asteroseismology?
I keep reading that a standard way to determine the age of a star is asteroseismology, and I tried to learn more about it. I am wondering if somebody could help me to describe the method in simple ...
- 5,657
2
votes
1
answer
209
views
How can a very old star be formed among Population III stars?
After looking at some articles about old stars, (this, that, and this Wikipedia article), I thought about how such an old and small star could have formed. As the early universe had very massive, ...
- 6,733
6
votes
2
answers
305
views
Absolute model ages of lunar craters
I have been looking at several articles on the dating methods of craters, but I am wondering how exactly the "absoluteness" creeps into it. I came across several methods that link crater &...
- 1,105
1
vote
0
answers
53
views
Is a star with 2/3 solar masses and 9/10 solar radii still in the main sequence?
As far as I know, K-type and G-type stars (among others) grow in radius as they age, eventually leading to red giant phases.
My question is, would a star that is about 0.66 solar masses and 0.94 solar ...
- 403
6
votes
2
answers
916
views
Is the age of the Universe really 13.8 billion years?
Ok, I know this has been asked by a lot of people, but my reason for asking this question is a bit different. Please read further.
I was watching a video by Fermilab (Start at 6:30, at 8:30 he ...
- 189
3
votes
2
answers
244
views
Is it be correct to say that we live in a young (only 14 billion years old) universe?
From what I have read, it seems that our universe is expected to function more or less as it does now for some $10^{12}$ years, possibly more. If that is correct, our universe's current age of $14$ ...
- 133
7
votes
2
answers
779
views
How do we measure the age of the universe?
As mentioned in wiki/Age_of_the_universe,
The current measurement of the age of the universe is around 13.8 billion years (as of 2015) – 13.799±0.021 billion years
When my friend who is not from ...
- 1,007
2
votes
0
answers
121
views
Stellar age determination - code
I'm trying to determine the age of some stars. I have many parameters that characterize these stars: $T_{eff}$ ,log ${g}$ ,$[Fe/H]$, $V$... I've tried to use the isochrones package but so far no ...
- 391
43
votes
5
answers
11k
views
Are photons aged?
If a star is at a distance of one lightyear, how old are its photons when they reach earth (from the photons’ perspective)? If time dilation is near zero at light speed, can we assume that the light ...
- 439
6
votes
3
answers
376
views
Is there a stellar database that indicates how long ago stars in our Galaxy formed?
There are several ways of determining the age of a star: its position in the HR diagram, the presence of a protoplanetary disk, it belonging to a cluster...
When did the stars in our Galaxy form? Do ...
- 17.7k
0
votes
1
answer
678
views
Age of earth relative to other planets
Relative to the average age of other known planets, is the earth young, old or in the middle? Does it make a difference if you compare the earth against nearby planets (say < 500 LY), or other ...
- 103
5
votes
1
answer
2k
views
How to evaluate the fit of an isochrone to a stellar population?
Consider that I know the extinction, distance modulus, reddening, and metallicity for a particular star cluster.
I need to determine it's age from isochrone fitting.
After generating the required ...
- 333
0
votes
0
answers
31
views
Relationship between IMF and time spent during an evolutionary phase
I was reading a little about stellar evolution and was wondering whether there was any relationship between the lifetime of an evolutionary phase and the IMF, I searched on google but all I found were ...
- 333
11
votes
2
answers
539
views
Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?
I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
- 387
6
votes
1
answer
510
views
Can someone calculate the age of the KOI-4878 star?
The star’s low metallicity and fairly high space velocity suggest that KOI-4878 is older than the Sun.
But I don't know how to calculate an estimation for the age.
KOI-4878 data on Simbad
user30548
3
votes
1
answer
210
views
Could the Universe really be 12.5-13 billion years old?
My initial reaction is that "this must be wrong" and apparently that's a lot of people's initial reaction according to the article.
https://www.nbcnews.com/mach/science/universe-may-be-billion-years-...
- 24.2k
8
votes
1
answer
221
views
How far would EGSY8p7 be away now?
Apparently EGSY8p7 is the object with the longest light travel distance, 13.2 gly or a redshift of z = 8.68 (Wikipedia).
So the light took 13.2 billion years to travel to us from that object, but we ...
- 183
6
votes
1
answer
281
views
Do we know how old the matter that makes us is?
Last weekend, I had the pleasure of visiting an observatory where there was a series of lectures to cover up the fact that there was too much cloud cover to actually observe much at all.
One of these ...
user20278
2
votes
0
answers
183
views
How to derive the equation for the age of a flat universe with a positive cosmological term?
Can anyone show the steps involved in deriving this equation from the friedmann equation with the cosmological constant involved
- 61
4
votes
4
answers
4k
views
Why is the main sequence often called 'zero age' main sequence?
The main sequence stage for a star begins after it stars burning hydrogen into helium. This is often referred to as the zero age main sequence.
This is confusing since stars have already lived ...
- 822
4
votes
1
answer
706
views
Use of type-I a supernovae as standard candle
Why only type -Ia supernovae are used as standard candle to calculate age of universe and why not type II, type Ib, type 1c ?
- 529
8
votes
2
answers
2k
views
Is the age of the universe relative to an observer's location in that universe?
According to Wiki the age of the universe is 13 billion years old, and I was taught that background radiation made the universe uniform in all directions.
Doesn't this define a sphere of space in the ...
- 947
4
votes
1
answer
253
views
What have we learned from the observation of most distant galaxies [closed]
We have seen galaxies around 13 billion years old. Since these galaxies formed so early in the history of the known universe, are there observables about these galaxies that are apparently different ...
- 4,504
1
vote
3
answers
893
views
Is our universe flat?
I heard our universe is flat. Then one question is puzzling in my mind. If our universe is really flat, why we measure distance from any point across in a spherical way. In other words, why we say, ...
- 1,007
5
votes
1
answer
178
views
How can we tell the age of a rogue planet?
Is it possible to find out how old is a planet, especially a rogue planet? I know that people measured the radioactive decays to determine Earth's age with some amazing accuracy, but what about ...
- 2,511
8
votes
2
answers
3k
views
Age of a black hole
Is there a way to determine the age of a black hole. Suppose 100 Billion years from now, if two black holes have exactly the same mass(say 30 M☉). One of them formed 10 Billion years from now and ...
- 528
4
votes
2
answers
3k
views
Does the age of the universe take into account General Relativity / Special Relativity?
It is generally accepted that the age of the universe is approximately 12-15 billion years old based on the speed of the expansion of the universe. Since everything is moving very fast away from us, ...
- 1,072
1
vote
2
answers
262
views
How can we explain high redshift numbers?
I just finished an introductory astrophysics course$^1$ and I have a lingering question that I can't seem to resolve.
We learned that for the first few hundred million years, the universe was pretty ...
- 11
0
votes
1
answer
3k
views
Redshift to calculate age of stars
In multiple articles I have seen the age of a star, within the milky way, referred to as its redshift (typically denoted by $z$). I know that $z$ can be calculated as $z=\frac{\lambda_{obsv} - \...
- 437
1
vote
1
answer
510
views
Description of Henyey tracks on wikipedia incorrect?
So, if you search for Henyey tracks on wikipedia (I know, the shame of it!) you will come across this statement:
The Henyey track is characterized by a slow collapse in near hydrostatic ...
- 1,394
4
votes
2
answers
165
views
Dating very old objects/events
After reading this space timeline, I have wondered how they managed to make these assumptions about various events like when the first black holes formed. This is obviously far beyond the good ol' ...
- 143
4
votes
1
answer
293
views
Where are we in an approximate timeline of the possibly habitable universe?
Our universe is supposedly 13+ billion years old and our Sun is a third generation star. It seems to me that we are now in a relatively young stage of the universe. How many generations of stars will ...
- 141
4
votes
1
answer
677
views
How is the Lithium Depletion Boundary used to determine the age of a stellar cluster?
According to my understanding of Soderblom et al. (2014), lithium ages of stars are determined as follows:
Determine lithium abundance from equivalent width measurement of Li$_{\mathrm{I}}$ ...
user5341
0
votes
2
answers
235
views
Could we estimate the age of the universe based on the planar property of the Solar System?
The Big Bang scattered planets and stars everywhere in three dimensions.
But after billion years of moving and interacting with each others through gravity, planets moved on the same plane.
Given ...
- 119
3
votes
1
answer
4k
views
How to tell a crater is old or not?
Based on Wikipedia, we can estimate the age of a planet's surface.
How to tell a particular crater is newly formed or not? It may have sharp edge.
Different astronomical objects may have different ...
- 3,157