Questions tagged [radial-velocity]

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What percentage of Earth-sized planets in a habitable zone can be detected by the radial velocity method?

What percentage of Earth-sized planets in a habitable zone can be detected by the radial velocity method? I understand that larger planets and closer planets are detected more easily; and I assume ...
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Cross-correlations between Lagrange and Fourier synthesis

In the context of forecast for large surveys, I have to make cross-correlations between 2D (with angular coordinates of Lagrange transformation for GC photometric and Weak Lensing) and 3D (Fourier ...
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Radial velocity exoplanet search - can mathematical details be explained? (Bayesian periodogram MCMC)

Radial velocity (RV) is one of main methods for exoplanet search. The popular description of the method sounds simple - one should measure periodic Doppler variation of a spectral line of a star and ...
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1answer
31 views

When graphing radial velocity measurements, whats the relationship between days and the orbital phase

I graphed the radial velocity measurements for various planets, however, I am able to calculate the RV and the phase but whats the translation between phase and days. I want it to be days vs RV.
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74 views

Computing radial-velocities from Cross Correlation data

How can I better fit a Gaussian curve to a CCF so that I get the most precise RV value? The image below shows the fitting where I compared the fitting by weighting by the uncertainties and not. There ...
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1answer
65 views

What does correcting for LSR mean in galactic velocities?

This is a two-part question, but both parts are related: I'm aware that modern astronomical software can correct velocities for the local standard of rest (LSR), but what does that really mean? As in,...
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1answer
69 views

Pair together light curve and radial velocity data of specified star

I would like to create a web application that works with light curves and radial velocities of stars with exoplanets. I found a NASA bulk data download with both light curves and radial velocities (it'...
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1answer
181 views

Is it possible that some of the confirmed exoplanets are in fact primordial black holes?

Recently astronomers discovered a black hole lying just 1000 light-years from Earth, in a triple star system (HR 6819) that can be seen with the naked eye. This discovery has increased the possibility ...
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Radial velocity data in ALADIN or TOPCAT for Binary Systems

I just installed both, Aladin and Topcat VO tools. I want to know how to search for: HD 226868 and A0620-00 radial velocity data or photometric curves to derive the hidden black hole mass in those ...
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1answer
47 views

Radial velocity curves

When I measure RV in a program for more spectral lines, will it be equivalent? I mean I measure RVs of a line in blue spectral region, RVs of a line in red spectral region... Many thanks.
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1answer
55 views

Wavelength and radial velocity

What is the relation between the wavelength and the radial velocity? I have a data: wavelength and intensity and I would like to plot intensity with respect to radial velocity - similarly as in the ...
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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 ...
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1answer
84 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 ...
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2answers
280 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?
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1answer
96 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 ...
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3answers
145 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, ...
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1answer
655 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 ...
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88 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....
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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? ...
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2answers
97 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 ...