<p>I'm a highschool student and in the process of writing a research paper of deriving period-lumniosity relation of Cepheid variable independently of the pre-existing PL relation. Thus, I need to derive distance to each Cepheid variable independently by using, for example, trigonometric parallax and Baade-Wesselink method. </p>

<p>In the process of using Baade-Wesselink method, I need to calculate the change in angular diameter, which is represented by ∆θ. The question is, how can I derive that value given fluxes from different bands (V,B, etc.. I'm using the SIMBAD database currently).</p>

<p>Which definite equation do I need to use to derive it?</p>

CC BY-SA 3.0
2016-08-10T19:45:48.430Z
What exactly is the data you have? Do you only have only have the total flux of the star in various bands and not an image? Have you seen [this paper](http://arxiv.org/pdf/1210.7150v1.pdf)?
zephyr
CC BY-SA 3.0
2016-08-11T07:04:33.013Z
@zephyr Thank you for the reference. The paper is the one I was looking for. The data I have is lists of V-R values and uncertainties over the period.
7_G.S.N
<luminosity><angular-diameter><cepheids>
Change in angular diameter of Cepheid variables
7_G.S.N
# Change in angular diameter of Cepheid variables

(Asked by: username_0 on 2016-08-09)

I'm a highschool student and in the process of writing a research paper of deriving period-lumniosity relation of Cepheid variable independently of the pre-existing PL relation. Thus, I need to derive distance to each Cepheid variable independently by using, for example, trigonometric parallax and Baade-Wesselink method.

In the process of using Baade-Wesselink method, I need to calculate the change in angular diameter, which is represented by ∆θ. The question is, how can I derive that value given fluxes from different bands (V,B, etc.. I'm using the SIMBAD database currently).

Which definite equation do I need to use to derive it?

**Tags:** luminosity, angular-diameter, cepheids
> **Comments:**
> **username_1**: What exactly is the data you have? Do you only have only have the total flux of the star in various bands and not an image? Have you seen [this paper](http://arxiv.org/pdf/1210.7150v1.pdf)?  
> **username_0**: @zephyr Thank you for the reference. The paper is the one I was looking for. The data I have is lists of V-R values and uncertainties over the period.  

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## 0 answers

