2016/02/06 by Bahar Bidaran, Mohammad Taghi Mirtorabi, Fatemeh Azizi
Engineering · Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Atmosphere (unit) #CCD and CMOS Imaging Sensors #Calibration #Effective temperature #Geometry #Index (typography) #Line (geometry) #Materials science #Measure (data warehouse) #Meteorology #Optics #Physics #Sensitivity (control systems) #Sky #Spectral index #Spectral line #Stars #Stellar, planetary, and galactic studies #Titanium #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stw051
published as MNRAS, 457, 2043-2047 (2016) · Published in MNRAS
openalex publication_date 2016/02/06 · arxiv created 2016/12/25 · arxiv updated 2016/12/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 Teff = 2800 up to Teff = 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.