双星与变星研究组知识库

LM And is a neglected close binary system with a period about 18 h. First complete multi-colors CCD light curves are presented which reveals that LM And is beta Lyrae-type eclipsing binary. By analyzing two spectrums, we determined its spectral type of F6 for this binary. Photometric solutions of the binary were obtained by analyzing our multi-colors light curves and the TESS Light curve with the Wilson-Devinney method. The orbital inclination is about 84 degree revealing that the binary is a total eclipsing system. The mass ratio is determined to be about 0.54 and 0.58 for two sets of light curves. It is discovered that LM And is a semi-detached near contact binary where the secondary component is filling the critical Roche lobe, while the primary is more than 90% filling its Roche lobe. A period investigation suggests that the orbital period of the binary is increasing continuously at a rate of dP/dt = 4.2(+/- 0.6) x 10(-7) days/year, which may be attributed to mass transfer from the less-massive component, which fills its Roche-lobe. Therefore, LM And with period increasing will evolve into the contact configuration.