SIMBAD references

We introduce a new colour index consisting of two spectral bandwidths to measure the titanium oxide (TiO) absorption band strength centred at 567 nm. Based on the most up-to-date line list for TiO, we regenerate a grid of synthesized spectra and investigate the temperature sensitivity of the index. The new index behaves similarly to the older TiO index of Wing, in that it decreases monotonically from the coolest atmosphere with T_eff=2800 up to T_eff=4000 where the TiO molecules disassociate. To further examine the feasibility of the new index, we reproduce the calibration using a list of observed high-resolution spectra and we find similar results. This index extends the TiO absorption band capability to measure the effective temperatures of late K to M stars to the visual spectrum, where it is more accessible to small telescopes for long-term dedicated observation.