Direct Spectrum of the Benchmark T dwarf HD 19467 B

TL;DR

This paper presents spectroscopic measurements of the T dwarf HD 19467 B, confirming its spectral type as T5.5+/-1, and discusses its potential to independently determine fundamental properties like mass, age, and metallicity.

Contribution

First spectroscopic characterization of HD 19467 B confirming its spectral type and temperature, highlighting its potential as a benchmark for substellar property determination.

Findings

Confirmed T5.5+/-1 spectral type

Measured effective temperature ~978 K

Detected significant methane absorption

Abstract

HD 19467 B is presently the only directly imaged T dwarf companion known to induce a measurable Doppler acceleration around a solar type star. We present spectroscopy measurements of this important benchmark object taken with the Project 1640 integral field unit at Palomar Observatory. Our high-contrast R~30 observations obtained simultaneously across the $JH$ bands confirm the cold nature of the companion as reported from the discovery article and determine its spectral type for the first time. Fitting the measured spectral energy distribution to SpeX/IRTF T dwarf standards and synthetic spectra from BT-Settl atmospheric models, we find that HD 19467 B is a T5.5+/-1 dwarf with effective temperature Teff=$978^{+20}_{-43}$ K. Our observations reveal significant methane absorption affirming its substellar nature. HD 19467 B shows promise to become the first T dwarf that simultaneously reveals its mass, age, and metallicity independent from the spectrum of light that it emits.