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Cepeid B star data required

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Cepeid B star data required

Hello all,

Maybe my request is kind of odd. Through the BSM observing section I have been observing AS Cas. This is a Cepheid B variable star that, as I see now with all of its kind, has not been observed very much or in some cases not at all.

I have gathered already some data, and I am aiming to find out the following information about this star: period, distance, temperature, mass, spectral type, etc. This either are not well defined or not defined at all. In a "pre-calculation" with the data I have, it yields that using the Leavitt distance modulus on VStar, that this star might be around 30,000 l-y away from us, which puts it in the outskirts of our galaxy.

I need a well observed Cepheid B star data, in order to corroborate the calculations I am doing with AS Cas. Unfortunately, I have not found a single Cepheid B star within the database that has sufficient data to do this verification.

Does anybody about a Cepheid B star that has enough data, or at least in which survey I can find one? Any help will be most appreciated.

Enrique Boeneker

Sebastian Otero
Sebastian Otero's picture
Lists of double-mode cepheids

Hi Enrique,

You can use VSX to get a list of all double-mode cepheids in the galaxy.

Click on the More button twice to get a list of extended search options.
Enter %CEP%(B)% in the variability type search box.
The result will show 155 records including F/1O stars classified as DCEP(B) and 1O/2O stars classified as DCEPS(B).

But since you only want stars with data in the AID, you may get a list including only stars with AAVSO data by checking the "Observations in the AAVSO International Database" box.
This way the results will only be 25.

Checking the number of observations you will see that there is a single star that clearly stands out from the rest (it has 26568 observations):
TU Cas, a bright object (range 6.88 - 8.18 V) also in the same constellation.
It is at 00 26 19.45 +51 16 49.3 and has a period of 2.139298 d.

If you need data on other objects, you may find survey observations by going to each individual cepheid star page and then using the VSX external links.
The most useful datasets you will find are those from ASAS-3 (stars South of +28 between mag. 7 and 13) and ASAS-SN (all sky, between mag. 10 and 16) but you may want to try other surveys as well.

About AS Cas itself, the VSX fundamental period (coming from the GCVS) is 3.02125 d. and the ASAS-SN period is 3.0243327 d. so it may need some tweaking.

If you want to download ASAS-SN data for AS Cas and analyze them, follow the ASAS-SN Sky Patrol link, write 3300 in the "Enter number of days to go back" field (to get all available observations, in V and g bands) and un the next page click on "Re-compute this light curve" at the bottom. If you click on the ASAS-SN identifier link (ASASSN-V J002537.77+641347.9) you will end up on the page linked above and those data are reduced differently and there are far less observations (only V).

I hope this information is useful for you.


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