# Tag Info

10

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. If you have that idea in your head already then you are ready to drop the image because: The sheet is 2d but spacetime is 4d The 2d sheet is embedded in 3d ...

6

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 satellite, specifically the end of quarter 17. Every 90 days, which NASA calls a quarter, the space craft does a 90 degree roll to optimize the solar panel efficiency. ...

5

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 exists) is supposed to be one of the smallest planetary candidates found by Kepler and will have a barely detectable transit (depth of order 0.004%). The small ...

5

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 gravity wells you find in some science museums, and roll small balls on it, it's a pretty good model of orbits in 3D Newtonian gravity, with the correct 1/r2 ...

4

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 a rate of 0.02 and reaches its pre-burst luminosity with apparent magnitude of 10 to 12. Usually binoculars (take 8x42) will be able to spot this with ...

4

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 the absolute value of the luminosity you get will also be shifted systematically up or down by whatever distance you adopt. The V-band only contains a small ...

4

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 astronomynotes.com: Also, as Rory Allsop points out, the scale of the change in brightness is very different. Cepheid variables can be seen at great distances,...

4

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 emission, gamma rays, or x-rays you would expect to see from a neutron star. Also something as heavy as a nearby neutron star would have a lot of gravity ...

3

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 TMID is integer seconds from Julian Date 2453005.5, Kepler uses BKJD = Barycentric Kepler Julian Date, but offset by 2454833.0. i.e., BKJD = BJD - 2454833.0. The SuperWASP ...

3

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/

3

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 period of 11 years (in the bottom panel you also see Earth's, as this is a local measure, and thus is mostly affected by our distance from the sun) Patterns of ...

3

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 have to obtain a correct phase folded plot. You rightly call it "messy", the most likely reason is that the period you chose is wrong (assuming the data actually contains a periodic ...

3

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 data from here? If so, depending on what you will use it for it might be a good idea to look for spurious variability and remove it (for example, section 2.2 of ...

3

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 frequency range. Not knowing much about the SMEI sensor and where on the sky it has been looking at, I struggle to give you a full recipe. If you have for an object ...

2

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 while you should calculate the uneclipsed mean or median flux only for the non-transit time (with using median it possibly has only a tiny influence, yet it ...

1

Antispinwards is correct. However, for the practical purpose of estimating a mass, you can construct a mass-radius plot for all the exoplanets with known mass, use this to define a mean mass-radius relationship (which has significant scatter), and then use that relationshipto assign a mass to your planet.

1

Of course you will get multiple peaks in the periodogram. The Fourier series representing a non-sinusoidal signal will contain frequencies at multiples of the fundamental frequency. Similarly, you can have a periodic signal with double or treble the period which will look identical, but where the phenomenon causing the signal repeats either two or three ...

1

Nickel 56 decays to Cobalt 56 via electron capture decay, with a half-life of 6.1 days and a decay constant of $\lambda = 1.31\times 10^{-6}$ s$^{-1}$. About 1.75 MeV of energy is lost as gamma rays and a further 0.41 MeV in the form of an electron neutrino (Nadyozhin 1994) Let's assume that we are talking about the period of time after the initial ...

1

The radius of the planet is 0.17% of Jupiter's radius. Under the "Planet" info on the left, it says $R_P$ which is the radius of planet, and since the units are shown as $[R_J]$ this is the value is in comparison to Jupiter. It also gives the $M_P$ (mass of planet) in relation to $M_J$ (mass of Jupiter) as well. The interesting thing here is the ...

1

An excellent page to get most or all names for a star is Simbad which also happens to know the Kepler IDs (KID). Ont the other hand, every of the RV data files contains info on the star's identifier it belongs to in the header, e.g: \STAR_ID='HD 4628' So using Simbad you should be able to do a cross-matching. SimBad allows scripted query and includes ...

1

The file format for submitting observations to AAVSO sheds some light on this. "Visual" data are estimates by visual comparison to nearby reference stars of similar brightness. U, B, V, R, I data come from CCD cameras using standard filters in the Johnson-Cousins photometric system, with passbands ranging from near ultraviolet to near infrared. The J and H ...

1

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 its magnitude. Do trapezoid. This is an approximation, but it is better than reconstructing the SED that makes you rely more on assumptions for most circumstances,...

1

Following Mick's comment, I found an astropy-function - DAOStarFinder - that does what I was looking for. It scans an image for light-sources and one can set threshhold for a detection, e.g. the "roundness", "sharpness" or brightness of an object have to be between [-0.05,0.05], [0.6,0.8] or >5*standard_deviation, respectively. I must say, that I have the ...

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