10 votes
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Confused about rubber sheet analogy!

The rubber sheet only is not meant to be a qualitative model, it gives one concept and one concept only: Mass causes curvature of spacetime. You can't get any more than that from the rubber sheet. ...
James K's user avatar
  • 118k
9 votes

Gravitational mirroring: Can we theoretically see the Milky Way using a telescope?

In theory, it's possible, but in practice it's extremely unlikely. The deflection angle is small unless the light ray passes very close to the centre of mass of a compact lensing body. From Wikipedia, ...
PM 2Ring's user avatar
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8 votes
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On the "periodic" lightcurves of Active Galactic Nuclei

I don't think what you're seeing is periodicity; my bet is that it's just stochastic red noise. Searches for periodicity or quasi-periodic oscillations (QPOs) in AGN light curves is a difficult and at ...
HDE 226868's user avatar
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7 votes
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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

Why did it take so long for SN1987A to reach peak brightness?

Here's the abstract of a relevant article from Astrophysical Journal (December 1993), by Li, Hongwei; McCray, Richard; Sunyaev, Rashid A. DOI: 10.1086/173534 Iron, Cobalt, and Nickel in SN 1987A ...
PM 2Ring's user avatar
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6 votes

What caused instant jumps and exactly flat periods in Kepler's light curves?

There are two separate points of interest you're looking at so I'll separate this into sections. Sudden Drop at Day 1559 As near as I can tell, this is the result of a quarterly roll of the ...
zephyr's user avatar
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6 votes

Has the new type II supernova SN 2023ixf's subtype been determined yet, and is a tentative light curve possible? Is it still getting brighter?

The TL;DR is that in the optical, it rose in brightness over about a week and is currently in a plateau. It might stay that way for a few months or it might buck the trend and begin to dim -- we don't ...
HDE 226868's user avatar
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5 votes
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creating asteroid light curves and analysing them

I am the developer of the software shown in the tutorial video. After seeing your post last year, I decided to create a version of it that runs natively on macOS. It took me nearly twelve months to ...
AsmCoder8088's user avatar
5 votes

Confused about rubber sheet analogy!

I just wrote an answer about this. The rubber sheet is a good model of 2D Newtonian gravity, with a 1/r force law. If you make a rigid surface in the shape of the 3D gravitational potential, like the ...
benrg's user avatar
  • 3,802
5 votes

Get orbital period of exoplanet from light curve using astropy.timeseries

The second light curve you show has no obvious periodic behaviour and I cannot see any sign of a planetary transit. The period-finding algorithm appears to be working correctly. The planet (if it ...
ProfRob's user avatar
  • 149k
5 votes

How does one actually fold a light curve?

Assume I have a bunch of measurements of something like brightness or flux versus time, and I know or guess a period for these data. Pick a zeropoint in time - say the time of the first observation - ...
ProfRob's user avatar
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4 votes
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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
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4 votes

Could Tabby's star be beamed by a neutron star's jet causing irregular star spots?

I think this scenario is unlikely. There is no evidence Tabby's star is near a neutron star. Astronomers are monitoring Tabby's star very closely and there has not been any detection of the radio ...
Kyle's user avatar
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4 votes

Converting Light curve to Luminosity

To calculate a "luminosity light curve" from a time series of V-band photoetry, you need two things. You need to know the distance. The distance to Betelgeuse is uncertain and that means ...
ProfRob's user avatar
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4 votes
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How do you tell if a variable star is periodic or not by its light curve?

There are some nice and well-tested routines to create periodograms and test the periodicities for significance in the astropy.timeseries package, containing the LombScargle class. This class includes ...
ProfRob's user avatar
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4 votes
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How much time do I have left to easily spot the recently brightened Recurrent Nova RS Ophiuchi with binoculars and mild light pollution?

RS Ophiuchi is "Currently" Shining at a apparent magnitude of 5.12 (initially 4.6.) . It is fading at a rate of 0.01 and continues this progress for the next 43-47 days. Then it will fade at ...
Kavin Ishwaran's user avatar
3 votes

Binning a Phase Folded Lightcurve

tl;dr: try a finer frequency grid to obtain the correct period, bin it with the function astropy.timeseries.aggregate_downsample Before addressing the binning, you ...
Prallax's user avatar
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3 votes
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How do I phase fold the light curve for a variable star?

"Phase folding" is just a procedure whereby you replace the time-axis values by t % P, where P is the period and % is the modulo operator that returns the remainder of t/P. There are are a ...
ProfRob's user avatar
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3 votes

Calibrating raw photometric measurements

I have never worked with SMEI but I do have some experience with photometry and, while I do not understand completely the question, I think I can give you some ideas. First of all, did you get the ...
Solfreludio's user avatar
3 votes
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Calibrating raw photometric measurements

If I understand the question correctly, you have raw data from a CCD sensor in arbitray units (which correlate with brightness) and your challenge is to callibrate this intensity for a certain ...
B--rian's user avatar
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3 votes
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Get orbital period of exoplanet from light curve using astropy.timeseries

I think you may be seeing the planet in the periodogram! But also another signal - higher harmonics of other periodic signals example - various periodic signals in our sun - with a characteristic ...
zephyr's user avatar
  • 148
3 votes

Where can I download processed data of the Kepler telescope?

What you are looking for is here. http://archive.stsci.edu/kepler/search_retrieve.html This one is good for exoplanet light-curves https://exo.mast.stsci.edu/
Dean Pitts's user avatar
3 votes
Accepted

Plot SuperWasp Lightcurves

Not sure what you are expecting to see from the two datasets. Both datasets are examples of light curves, flux against time with different arbitrary origins for the time axis; SuperWASP ...
astrosnapper's user avatar
  • 8,347
3 votes

Fourier analysis of exoplanet transit to determine the number of planets in the system

As AtmosphericPrisonEscape mentioned in a comment, this could in principle be done, but there are some difficulties involved. Let's consider a very idealistic case in which we are able to measure the ...
Prallax's user avatar
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3 votes
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What determines how accurate a particular method is at finding the period between Lomb-Scargle and String Length Minimization?

I think they are just not the best period-finding algorithms. They are too simple. For high signal-to-nose data with SINGLE periods they seem to work ok, but the problem is always with low-quality ...
JOAQUÍN HERNÁNDEZ's user avatar
3 votes

On the "periodic" lightcurves of Active Galactic Nuclei

AGN's are divided into roughly 3 types, Quasars, Seyfert galaxies and radio galaxies. All of these produce light, each in their own electromagnetic spectrum and intensity like quasar emits across all, ...
Arjun's user avatar
  • 1,256
2 votes

Comprehensible full manual for bolometric light curve reconstruction

If you want a bolometric light curve from photometric points, you don't need to reconstruct its SED inside the range you already have data points. Use effective central wavelength of each band with ...
Kornpob Bhirombhakdi's user avatar
2 votes
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Calculate depth and duration of exoplanet's transit using Python, astropy or lightkurve

Calculation of both, depth and duration, is usually done not on the raw data but derived from a fit to the data. In your last three lines of code you also calculate the average / medium over all data ...
planetmaker's user avatar
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2 votes
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Obtaining the Light curve of a a Quasar

As described in Paris et al. 2018, in that catalog you don't have the info for creating light curves. If you go like here: http://skyserver.sdss.org/dr16/en/tools/chart/navi.aspx you can get the ...
Alessandro Peca's user avatar
2 votes

How to find luminosity from a light curve?

It's unclear what kind of luminosity you're trying to determine. If it's bolometric luminosity (from photons of all wavelengths), then planetmaker is right, and you need (calibrated) observations at ...
Peter Erwin's user avatar
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