Questions tagged [radial-velocity]

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11
votes
4answers
9k views

Is Earth's Surface “In orbit”?

I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...
2
votes
1answer
73 views

How spectrographs that measure radial velocities manage to translate variations in the stars' spectrum lines into the “speed” of the star?

Like ESPRESSO or CARMENES, for example. I just don't understand the process or the way these spectrographs manage to obtain the velocity of the "wobble" of the star (due to the presence of another ...
2
votes
2answers
108 views

How does one calculate inclination from a graph of radial velocity?

If a binary star system has a non-zero inclination, how would that show up in a graph of radial velocity? How could I then extract the inclination from the graph?
1
vote
0answers
40 views

Doppler Spectroscopy - Finding mass of an exoplanet

An astronomer, T observed the spectrum of a distant star X. The spectral lines were observed to have tiny blueshifts and redshifts regularly with a period of 1.27 years. T concluded that the star is ...
3
votes
3answers
105 views

Why is it impossible to estimate the inclination of an exoplanet with the Radial Velocity Method?

The formula of the radial velocity is: $$v_i= V - K(\sin(f_i+\omega)\ + e\sin\omega),$$ with $$K = \frac{m_p}{m_s+m_p}\frac{na\sin i}{\sqrt{1-e^2}}.$$ Being $V$the systematic velocity of the system, ...
3
votes
1answer
287 views

Calculate the orbital phase when plotting the Radial Velocity data of a transitting exoplanet

I'm not quite sure how I find the orbital phase ($\phi$) of a transitting exoplanet. For example, I have this RV data in this article: First of all, I don't know how that phase or "cycles" is ...
5
votes
1answer
72 views

How are exoplanets with 10,000 day periods discovered with the radial velocity method?

The radial velocity technique has apparently been used to discover exoplanets with extremely long orbital periods of ~10,000 days. For example, see this link: https://exoplanetarchive.ipac.caltech....
1
vote
0answers
70 views

Plotting GAIA barycentric radial velocity data with python

Does anybody know of a good tutorial on how to use python and astropy to generate plots of GAIA, RAVE or any other database of barycentric (heliocentric) radial velocity data of stars in our galaxy? ...
4
votes
2answers
83 views

Radial Velocity Clarification Sought

According to Google, radial velocity is "the velocity of a star or other body along the line of sight of an observer". The radial velocity of Sirius according to Google is −5.50 km/s. If the ...