Physical parameter determinations of young Ms. Taking advantage of the Virtual Observatory to compare methodologies

TL;DR

This paper compares different methodologies for determining physical parameters of young M-type stars, highlighting how data and method choices can lead to significant temperature discrepancies, and utilizes the Virtual Observatory framework for analysis.

Contribution

It demonstrates the impact of methodology and data choice on temperature estimates of young M-type stars using Virtual Observatory tools.

Findings

Differences in temperature estimates can reach up to 350 K due to methodology.

Temperature differences are smaller for colder objects despite complex fitting.

Using Virtual Observatory frameworks facilitates comparative analysis of stellar parameters.

Abstract

One of the very first steps astronomers working in stellar physics perform to advance in their studies, is to determine the most common/relevant physical parameters of the objects of study (effective temperature, bolometric luminosity, surface gravity, etc.). Different methodologies exist depending on the nature of the data, intrinsic properties of the objects, etc. One common approach is to compare the observational data with theoretical models passed through some simulator that will leave in the synthetic data the same imprint than the observational data carries, and see what set of parameters reproduce the observations best. Even in this case, depending on the kind of data the astronomer has, the methodology changes slightly. After parameters are published, the community tend to quote, praise and criticize them, sometimes paying little attention on whether the possible discrepancies come from the theoretical models, the data themselves or just the methodology used in the analysis. In this work we perform the simple, yet interesting, exercise of comparing the effective temperatures obtained via SED and more detailed spectral fittings (to the same grid of models), of a sample of well known and characterized young M-type objects members to different star forming regions and show how differences in temperature of up to 350 K can be expected just from the difference in methodology/data used. On the other hand we show how these differences are smaller for colder objects even when the complexity of the fit increases like for example introducing differential extinction. To perform this exercise we benefit greatly from the framework offered by the Virtual Observatory.