Stargazing А neutron star and a photon sphere

AI Thread Summary
Photon spheres can theoretically exist around neutron stars if their radius is less than 1.5 times the Schwarzschild radius, despite the Oppenheimer-Volkoff limit suggesting otherwise. The discussion highlights the contradiction between the mass-radius relationship of neutron stars and the conditions required for photon spheres. Some equations of state may permit neutron stars to be ultracompact, allowing for the existence of a photon sphere. The existence of such neutron stars remains a topic of debate among astrophysicists. Overall, the potential for photon spheres around neutron stars raises questions about their physical properties and limits.
daggab
Messages
3
Reaction score
0
Wikipedia(https://en.m.wikipedia.org/wiki/Photon_sphere):
'This equation entails that photon spheres can only exist in the space surrounding an extremely compact object (a black hole or possibly a neutron star)'
But how can a neutron star?
I have a doubt because
1. When а mass of а star increases, radius decreases.
2. The radius of the most massive NS exceeds the schwarzschild radius.
3. We know Oppenheimer-Volkoff limit roughly. It is not known exactly.
I suppose that the existence of such neutron stars is questionable.
Is it correct?
 
Astronomy news on Phys.org
daggab said:
We know Oppenheimer-Volkoff limit roughly.
Hi daggab:

The Wikipedia article text indicates that at a neutron start of radius r,
rs < r < (3/2) rs,​
could have a photon sphere. Are you saying that the Oppenheimer-Volkoff limit is inconsistent with this?

Regards,
Buzz
 
  • Like
Likes daggab
If you follow the link to reference [1] in that Wikipedia article, it links to a paper "Properties of ultracompact neutron stars" which mentions that certain equations of state would allow a neutron star to be less than 1.5 times the Schwarzschild radius and hence have a photon sphere.
 
  • Like
Likes daggab

Thread 'Does it make sense to build new radio telescopes?'

TL;DR Summary: In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect alien signals, it will further expand the radius of the so-called silence (or rather, radio silence) of the Universe. Is there any sense in this or is blissful ignorance better? In 3 years, the Square Kilometre Array (SKA) telescope (or rather, a system of telescopes) should be put into operation. In case of failure to detect...
View full post »
Thread 'Could gamma-ray bursts have an intragalactic origin?'

Thread 'Could gamma-ray bursts have an intragalactic origin?'

This is indirectly evidenced by a map of the distribution of gamma-ray bursts in the night sky, made in the form of an elongated globe. And also the weakening of gamma radiation by the disk and the center of the Milky Way, which leads to anisotropy in the possibilities of observing gamma-ray bursts. My line of reasoning is as follows: 1. Gamma radiation should be absorbed to some extent by dust and other components of the interstellar medium. As a result, with an extragalactic origin, fewer...
View full post »

Thread 'Could fast radio bursts be alien radar signals?'

Both have short pulses of emission and a wide spectral bandwidth, covering a wide variety of frequencies: "Fast Radio Bursts (FRBs) are detected over a wide range of radio frequencies, including frequencies around 1400 MHz, but have also been detected at lower frequencies, particularly in the 400–800 MHz range. Russian astronomers recently detected a powerful burst at 111 MHz, expanding our understanding of the FRB range. Frequency Ranges: 1400 MHz: Many of the known FRBs have been detected...
View full post »

Similar threads

B Neutron star 4U 1820-30 spins at 716 revolutions per second
Replies
0
Views
2K
B If Quark stars exist why do Neutron stars become Black holes?
Replies
17
Views
5K
B Stars massive enough to evolve into black holes
Replies
5
Views
3K
Neutron Star Collapse: Q&A on Physics and Observation
Replies
9
Views
3K
Neutron Star Collapse: Upper Limit & Physics Explained
Replies
2
Views
2K
I What happens when a Neutron Star forms a Black Hole?
Replies
17
Views
2K
Neutron star collapse can produce GBBs?
Replies
4
Views
3K
A Falsifications and constraints due to GW measurements
Replies
19
Views
5K
What is a Photon Sphere: Definition and Properties
Replies
1
Views
9K
What is the photon sphere and where is the singularity in a black hole?
Replies
2
Views
4K

Hot Threads

Recent Insights

Back
Top