Reddening-Free Q Parameters to Classify B-Type Stars with Emission Lines

The emission-line B-type stars constitute a heterogeneous group. Many of these show similar optical spectroscopic features and color indices, making it difficult to classify them adequately by means photometric techniques. Thus, is relevant deal with appropriate classification criteria avoid as many selection effects possible. For this purpose, we analyzed different reddening-free Q parameters, taking advantage the Gaia 2MASS surveys, for both main sequence stars. Along work, provided various search normal stars, using color–color, Q–color, Q–Q diagrams. It was also possible identify in transition phases (i.e., (Rp−J) vs. (J−Ks) diagrams) according their NIR radiation excesses (Bp−Rp) (H−Ks) diagram). Other diagrams, such QJKHK or QBpJHK (Bp−Ks), were very useful classes emission lines. These diagrams highlighted presence several classified CBe, large that seemed be caused dust envelopes. Therefore, would misclassified. Three groups HAeBe intrinsic properties distinguished. amount diverse well-recognized via QJHK QBpRpHK diagram. are important tools automated designs machine learning optimal algorithms.