Q&A

Q1. There is already CMD website using YBC, why a separate YBC web site? The CMD website and the Trilegal code can be seem as a test case of using the YBC, but YBC can be used beyond this. For example, you can use it in your simulation, based on isochrones. Or if you wanna compare different isochrones from different research groups, but wish to distinguish from the differentce resulted by using different bolometric corrections.

Q2. How is the ISM extinction treated?
A: You are talking about the ISM extinction other than the cirsumstellar dust. Every spectrum used has been convlved with the extinction curve (Cardelli et al. (1989) + O'Donnell (1994) with RV=3.1.), therefore the spectral variation effect hass been considered. The non-lineararity as a function of Av amount has been also taken into account by computing grids with Av=[0., 0.5, 1., 2., 5., 10., 20] and interpolating among them.

Q3. How is the PoWR library being used?
A: Usually logg and logTeff are used for the interpolation. For WR stars, the transformed radius logRt is the more influential quantity other than logg. The tranformed radius is defined as:

R_t=R_* \left(\frac{v_\infty}{\rm 2500~ km/s} \middle/ \frac{\dot{M}\sqrt{D}}{10^{-4}~{\rm M_\odot/yr}}\right)^{2/3}.
For different types of WR models of PoWR, different clumping factor (D) has been used. To facilitate the interpolation, we have rescale the calculation of R_t by PoWR. Therefore the new R_t are clumping factor free for all the WR models.