Science

Page 1: Introduction and Background

Overview of the LHS 6343 System

  • LHS 6343 C: A benchmark brown dwarf orbiting a M-dwarf binary.

  • Characteristics: It is evolved and negligibly irradiated, making it ideal for calibrating sub-stellar evolution and atmospheric models.

  • Key Measurements:

    • Mass: 62.6 ± 2.2 MJup

    • Radius: 0.788 ± 0.043 RJup

    • Effective Temperature: 1303 ± 29 K

    • Bolometric Luminosity: log(Lbol/L⊙) = −4.77 ± 0.03

  • Spectral Type: T1.5 ± 1 derived from NIR emission spectra.

  • Data Sources: Used empirical stellar relations and Gaia DR3 for distance measurements.

Importance of Brown Dwarfs

  • Mass Gap: Brown dwarfs bridge the mass gap between planets (∼ 13 MJup) and stars (∼ 78.5 MJup).

  • Energy Sources: Unable to sustain hydrogen fusion, their luminosity and temperature decrease over time due to cooling.

Eclipsing Binaries and Evolutionary Models

  • Mass-Age Degeneracy: Distinguishes difficulty in identifying parameters of BDs using photometric observations alone.

  • Eclipsing Binaries: Serve as key systems to derive properties like mass and radius accurately through observations.

  • Characteristics of BDEBs: Should have minimal irradiation and are scarce in comparison to field BDs.

Page 2: Previous Analyses and Measurements

LHS 6343 Overview

  • Types of Studies: Previous studies used Keck/HIRES radial velocity and Kepler transit data to acquire direct measurements of LHS 6343 C.

  • Prior Measurements: 62.1 ± 1.2 MJup (mass) and 0.783 ± 0.011 RJup (radius) reported leading to various atmospheric models.

Eclipsing Binary Characteristics

  • Minimum Irradiation Contribution: Estimated at ~1% for the observed BD from host star LHS 6343 A.

  • Significance: These properties allow LHS 6343 C to serve as a reliable benchmark for understanding field BD characteristics.

Page 3: Observations and Data Acquisition

HST/WFC3 Eclipse Observations

  • Secondary Eclipse: Conducted over 7 hours with 102 exposures in G141 IR filter.

  • Data Reduction: Utilized ExoTEP pipeline due to specific calibration requirements unique to scan-mode observations.

Page 4: Light Curve Model

Fitting Procedures

  • Joint Eclipse Model

    • Instrument systematics included in the model to accurately reflect observed light curves.

    • Systematic behaviors identified included linear and exponential trends across the HST observations.

  • Model Selection: Seahorse package utilized for a robust modeling approach to analyze flux errors and regimes.

Page 5: Spectroscopic Data

Measured Emission Spectrum

  • Spectral Fitting: Conducted to find the best model that fits LHS 6343 C’s secondary eclipse.

  • Depth of Eclipse: Found to be 867 ± 21 ppm, which informs energy distribution estimates.

Page 6: Distance Measurement Issues

Gaia DR3 Implications

  • Distance Estimation: Measurements from Gaia reveal concerns regarding LHS 6343's dual star measurements leading to uncertainties.