New answers tagged observational-astronomy
-3
votes
How would a person know if a planet is orbiting a binary star?
You check the periodic frequency shift with the Doppler effect. The light from the two stars is not very suitable because each light source moves. Much better: The binary system (total mass $m_A\...
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-2
votes
What is the detection threshold of gravitational waves for LIGO?
The amplitude up to which GW can be detected depends solely on the signal-to-noise ratio of the antenna-receiver combination. An excellent antenna is of little use if the receiver is not of comparable ...
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2
votes
Accepted
Expected nature of LISA's data; will it be more like a forest of static peaks, or a series of individual events?
A discussion of the analysis of LISA data is given by Boileau et al. (2021). Specifically, they provide an in depth analysis of exactly the point you are interested in - to what extent is LISA able to ...
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2
votes
Formula for rate of expansion of the universe vs distance?
The relationship between proper distance and the rate of change of proper distance is Hubble's law. So
$$ v(r_0) = H_0 r_0 \ .$$
Note that $H_0$ is the Hubble parameter at the present epoch. The ...
- 146k
-1
votes
Are there any gaps in the range of gravitational wave frequencies we can detect?
The questioner and some answerers assume that whether one can receive GW depends solely on the wavelength/antenna length ratio. This is wrong, as examples from radio technology show:
a) For NMR in ...
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7
votes
Accepted
Where can i find dark frames in the ESO archive?
Calibration frames, including dark frames, for the ESO telescopes in general and the FORS2 instrument in this case, are taken by a general calibration program rather than the specific science program. ...
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3
votes
If 42000 Starlink satellites interfere with telescope observations from Earth would someone observing from another solar system detect them too?
Not in any way that is special to the Starlink satellites. Many satellites can interfere with earth-based astronomy because they are very close to the earth. A reflection off a satellite that is a few ...
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4
votes
Why is the H-alpha line slightly shorter in wavelength (656.28 nm) in air than in vacuum (656.46 nm)? Shouldn't it be longer?
This is not due to where the light is emitted, but where it is measured.
When light enters a medium, such as air, it slows down. This is called refraction (and is the reason that prisms etc can bend ...
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1
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Expected nature of LISA's data; will it be more like a forest of static peaks, or a series of individual events?
Our galaxy hosts probably more than $10^6$ binary stars with periods ranging from one day to about 100 days. Each is thought to have at least six planets orbiting it. Each planet has a different ...
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