DOI: 10.5281/zenodo.15001025
title: Luhman 16AB IGRINS Spectral Atlas

description: This is the dataset reported by Ishikawa et al. (2025) "A 1.48–2.48 μm 𝑅=28 000 spectroscopic atlas of the L7.5 and T0.5 components of the nearest pair of brown dwarfs: Luhman 16AB". It includes the H- and K-band high-SNR high-dispersion spectra of Luhman 16AB (WISE J104915.57-531906.1AB) from IGRINS (Gemini South) and the Sonora Bobcat Alternative B model that best fits them. Estimated best-fit parameters and the results of radial velocity (RV) analysis are also included. If these data help your work, please cite Ishikawa et al. (2025).

 

All files are text files and the lines starting with "#" are header comments. The following is a brief description of each of the four directories:

 

 

1. fitted_models_and_spectra

High-SNR IGRINS spectra of Luhman 16AB combined from all epochs, along with their uncertainties and the best-fit model spectra. Files are organised separately for each of the two components of Luhman 16A and B (L7.5, T0.5) and for each of the 46 echelle orders of IGRINS. This results in 2 × 46 = 92 individual files. 

 

Each file contains the following four columns (with fluxes normalised by the mean of each order):

# wavelength (um),    data flux,      uncertainty,     model flux

These are the data plotted in the second panel from the top in Figure B1 of APPENDIX B in Ishikawa et al. (2025).

 

 

2. all_combined_stitched_spectra_and_fitting_parameters

This directory contains all the data plotted in Figures 6 and 7 of Ishikawa et al. (2025), including order-stitched spectra and best-fit atmospheric parameters for each order. Files beginning with "fig6_" are for Luhman 16A, whilst those beginning with "fig7_" are for Luhman 16B. The letter following "panel_" in the filename corresponds to the panel designations in Figures 6 and 7. 

 

Panel a includes the spectra of each component combined from all epochs with all orders stitched together and their uncertainties. Panel b contains model spectra that incorporate only specific single molecules and collision-induced absorption (CIA). Panels c to i list the results of model fitting for each order (best-fit atmospheric parameters and the reduced chi-square goodness-of-fit statistic). For more details, please refer to Section 4.1 and the captions of Figures 6 and 7 in the paper.

 

For reference, the header rows of each file are provided below:

 

fig?_panel_a_flux.txt: 

# Wavelengths (µm),      Normalized flux

 

fig?_panel_a_uncertainty.txt:

# Wavelengths (µm),      Uncertainty

 

fig?_panel_b_single_molecule_spectra.txt:

# Wavelengths (µm),      H2O (W/m^2/m),           CH4 (W/m^2/m),           CO (W/m^2/m),            NH3 (W/m^2/m),           FeH (W/m^2/m),           H2 (W/m^2/m),            H2S (W/m^2/m)

 

fig?_panel_c_to_i_best_fit_parameters_in_each_order.txt:

# Mid-order λ (µm),      Teff,                    logg,                    fsed,                    Kzz,                     vsini,                   RV,                      Reduced chi-square

 

 

3. each_epoch_spectra

This directory contains reduced spectra for each epoch. Data for each echelle order are stored in separate subdirectories. The directory names follow the pattern "ascii_[H or K]order[orderID]", where the orderID corresponds to the order number m in Ishikawa et al. (2025) according to the following formulae:

        m = orderID + 98 for H band

        m = orderID + 71 for K band

For example, "ascii_Horder18/" contains data for order m = 116 and "ascii_Korder06/" for order m = 77.

 

Each file contains the following five columns:

# wav_both, flux_A, uncert_A, flux_B, uncert_B

Please note that the wavelength array is shared because both binary components of Luhman 16 were observed simultaneously on the slit. 

 

Each directory contains data files for each of the 93 epochs, plus a "fname.lst" file, which lists the file names in the directory in the order that the observations were taken. The mid-exposure times (Julian Day) for these epochs are recorded in "JDs.txt" in the same order. The corresponding barycentric velocity correction factors are in "BVCs.txt".

 

 

4. RV_data

This directory contains all the RV analysis data plotted in Figure 24 of Ishikawa et al. (2025). Three RV files "RV_Luhman16A.txt", "RV_Luhman16B.txt", and "RV_Luhman16B_relative_to_A.txt" contain the RV values (km/s) for Luhman 16A, Luhman 16B, and Luhman 16B relative to Luhman 16A, respectively, for each of the 46 orders across all 93 epochs. "JD_and_CRX.txt" contains the mid-exposure time (JD) for each of the 93 epochs, along with the chromatic RV index (Zechmeister et al. 2018). "wav_mid_order.txt" contains the mid-order wavelength (µm) for each of the 46 orders. For more details, please refer to Section 5.1 and the caption of Figure 24 in the paper.