# Tag Info

Accepted

### highspeed black holes or neutron stars on (almost) head-on collision course and kinetic energy

I think it's a fun question, and I can answer some of it. If their event horizons don't "touch" I'd assume their courses will change considerably but it would be a normal flyby - right? While ...
• 22.9k

### List of Moving stars on the northern hemisphere? [Stellar kinematics]

What you're looking for is stars with "High Proper Motion". A Google search of "High proper motion stars" will provide a number of such lists. A quick look at Wikipedia gives this link: https://en....
Accepted

### In 31.5kyr, Epsilon Eridani and Luyten 726-8 will be < 1ly close; but how distant from the Solar system?

These stars are currently moving away from us, in the case of Epsilon Eridani, at 15.5 km/s. In 31500 years they will be further away than they are now, the distance can be calculated by applying ...
• 91.3k
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### Create Position-Velocity diagram from a velocity field

Such diagrams are usually called rotation curves, and show the velocity of stars/gas in a disk galaxy viewed edge-on along the line of sight (LOS) as a function of distance from the center. That is, ...
• 33.8k

### List of Moving stars on the northern hemisphere? [Stellar kinematics]

SIMBAD allows you to search for stars given various criteria. I searched for: Dec > -20 (easily visible from most locations in the Northern hemisphere) Vmag < 4 (easy naked eye objects) pm > ...
• 91.3k
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### What are typical peculiar velocities?

From the virial theorem, peculiar velocities resulting from gravitational processes generally have magnitudes of the order of $$V \sim \left(\frac{GM}{R}\right)^{1/2},$$ where $G$ is the ...
• 33.8k
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### Derive LOSVD from galaxy spectrum, using fourier method

There were a few mistakes in the treatment of my spectra before fourier transform in the first place. So missing steps were: 1.) The spectra should be averaged to 0 by subtracting the median. 2.) You ...
• 359
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### Extracting kinematics from stellar spectra. Why are template stellar spectra necessary?

(Optically thin) Emission lines in nebulae are generally unresolved and have simple shapes that might be approximated by Gaussians. Stellar spectra are complicated - there are blends, there is ...
• 118k