Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 1992 | Published
Journal Article Open

Infrared photometry and spectroscopy of the brown dwarf candidate PC0025+0447


We have obtained I, J, H, Kf and L' photometry and infrared spectroscopy (λ/Δλ ≃ 100) from 1.2-2.4 µm of the unusual emission line M star PC0025+0447. The near infrared photometry shows that this star has infrared colors which are comparable to the latest M dwarf stars such as LHS 2924 and LHS 2065. The infrared colors of PC0025+0447 establish that this star is a dwarf and not a distant giant. The infrared spectrum is dominated by strong H_2O absorption bands, and these bands are the strongest measured in any dwarf. Since H_2O band strength increases with decreasing temperature it is very likely that PC0025-f 0447 is substantially cooler than any of the stars calibrated by Berriman & Reid [MNRAS, 227, 315 (1987)], i.e. T_(eff) < 2450 K. The CO first overtone absorption is much weaker in PC0025+0447 than in hotter M dwarfs. Comparison of the spectroscopy of PC0025-I-0447 with model atmospheres shows correspondence between the observed strength and shape of individual H_2O bands, although the H_2O band strength is systematically greater in the models. A practical spectral classification sequence and ultimately a temperature scale based on the strength of the infrared H_2O bands may be feasible for stars later than M6.5. A preliminary effective temperature for PC0025+0447 based on integrating the observed fluxes yields 1900 ±600 K. Spectroscopically the band strength suggests the lowest T_(eff) for any dwarf so far observed. We infer from the observed and theoretical evolutionary models that PC0025 + 0447 is either an old ( > 10^9 yr) H burning star, with M ≃ 0.08 M_☉, or a younger brown dwarf.

Additional Information

© 1992 American Astronomical Society. Received 14 April 1992 revised 6 July 1992. We are indebted to France Allard for making her M dwarf model atmospheres available to us, and for invaluable assistance in interpreting the infrared spectra of PC0025. This work was supported in part by NSF and the Alfred P. Sloan Foundation.

Attached Files

Published - 1992AJ____104_2016G.pdf


Files (755.9 kB)
Name Size Download all
755.9 kB Preview Download

Additional details

August 20, 2023
October 24, 2023