7 votes
Accepted

How do I get temperature and diameter from a light curve?

You can definitely calculate the diameter of the star. You could use the radiation law given here: Another method for measuring star diameters makes use of the Stefan-Boltzmann law for the ...
DialFrost's user avatar
  • 2,105
7 votes

How does the cepheid variables help in finding distance

Why not read his original paper? It's fairly short by today's standards, despite being such a monumental turning point in our understanding of the size and nature of the Universe. In short though, ...
zephyr's user avatar
  • 15k
5 votes

Did Gaia actually generate complete light curves for 212 Cepheids in other galaxies?

Am I naive to think that it is necessary to build up a nice, complete light curve with dense points in time in order to use the photometry for precision distance calculations? No, the more I read ...
Alex's user avatar
  • 2,265
4 votes

Period-Luminosity Relation of Cepheids via Gaia Data

Here is a similar plot I adapted from Clementini et al. (2019). It shows mean absolute Gaia G-magnitude (derived from Gaia-DR2 parallaxes) versus period for 998 known Cepheid variables. I guess that ...
ProfRob's user avatar
  • 149k
4 votes
Accepted

Other than Lomb-Scargle Periodograms and String Length Minimization, what other methods can be used to find the period of unevenly spaced data?

A common method is to use the autocorrelation function (ACF). A description of an application of this technique for finding the rotation periods of stars in Kepler data is given by McQuillan et al. (...
ProfRob's user avatar
  • 149k
4 votes
Accepted

Classification and discovery of stars

Cepheid variable stars and exoplanets transiting stars have very different light curves (the relation between brightness and time). Exoplanet light curve from NASA: Cepheid variable light curve from ...
FJC's user avatar
  • 1,324
3 votes

How to find a Cepheid's pulsation period using its graph?

This graph is not the light curve of a cepheid. It is used to find the average brightness of the star, and from that, estimate its distance. The rate at which cepheids pulse is related to their ...
James K's user avatar
  • 119k
3 votes

Did Gaia actually generate complete light curves for 212 Cepheids in other galaxies?

Casertano et al. used the period-luminosity (P-L) relation of Cepheid variables as a sanity check on Gaia DR1 parallaxes. They chose Cepheid variables within the Milky Way having parallaxes in TGAS (...
Mike G's user avatar
  • 18.6k
3 votes
Accepted

Deriving phase of a pulsating star from list of Julian date values of observing brightness

INT refers to the floor function. So $\mathrm{INT}(x)$ is the largest integer not exceeding $x$. In this case, the function is used to get the fractional part of $\frac{\mathrm{HJD}-T_0}{P}$, i.e. ...
wythagoras's user avatar
2 votes
Accepted

How to calculate a phase shift in the process of deriving Baade-Wesselinke distance?

It is admirable that you are tackling this type of problem as a high school student, but I really think that some of these topics are out of your grasp currently, partly because of the highly ...
zephyr's user avatar
  • 15k
2 votes

Which software is appropriate to integrate radial velocity with respect to time

I'm not sure what you are actually trying to do. Radial velocity isn't generally measured, it is computed from the projected velocity. But if I take you at your word, that your raw data is radial ...
Li Zhi's user avatar
  • 21
2 votes

How do astronomers distinguish between Cepheids and other types of variable stars?

Unambiguously unique (is there another kind of uniqueness?)? No. In fact in the 1950s it was discovered that Cepheid identification up to that point had often been inaccurate. But Cepheids do exist in ...
adrianmcmenamin's user avatar
2 votes

Measuring magnitudes in ds9

Unfortunately, simple photon counts are not going to get you to stellar magnitudes, because the response of the telescope is not perfectly linear or set to a consistent zeropoint. The point-spread ...
Elias's user avatar
  • 55
2 votes
Accepted

How does the Hubble Space Telescope "Drift and Shift"?

The "drift-and-shift" (DASH) mode was described in a paper by Momcheva et al. (2016), and works the way you supposed: a sequence of nearby images is taken using blind offsets without guide-star ...
Peter Erwin's user avatar
  • 16.7k
1 vote
Accepted

What does a fitted curve for the period of a variable star, tell me about the star?

In short, it can tell you a lot of stuff. You could identify (probably) the following: Type of star E.g. a light curve of a eclipsing binary system Light curve of supernova: Not only that you can ...
DialFrost's user avatar
  • 2,105
1 vote

Observing cepheid variables in other galaxies

It is correct that we can't observation stars in other galaxies with the unaided eye. But with telescopes, we can see much more, including individual stars in other galaxies. We certainly have plenty ...

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