Project 1640 Observations of Brown Dwarf GJ 758 B: Near-Infrared Spectrum and Atmospheric Modeling
| Autor: | S. Luszcz-Cook, Richard Dekany, D. Brenner, Chengxing Zhai, Emily L. Rice, Neil T. Zimmerman, Lynne A. Hillenbrand, Rob Fergus, Rick Burruss, Ian Parry, E. Bacchus, Ricky Nilsson, Thomas Lockhart, Chas Beichman, Sasha Hinkley, P. A. Giorla Godfrey, David L. King, Gautam Vasisht, Rebecca Oppenheimer, Rémi Soummer, Aaron Veicht, Laurent Pueyo, Anand Sivaramakrishnan, Eric Cady, Jonathan Aguilar, L. C. Roberts |
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| Přispěvatelé: | Parry, Ian [0000-0001-6113-0384], Apollo - University of Cambridge Repository |
| Rok vydání: | 2017 |
| Předmět: |
planets and satellites: detection
Brown dwarf FOS: Physical sciences Astrophysics Type (model theory) instrumentation: adaptive optics 01 natural sciences stars: individual (GJ 758) Spectral line law.invention 010309 optics Telescope law 0103 physical sciences 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) instrumentation: spectrographs Physics Earth and Planetary Astrophysics (astro-ph.EP) Near-infrared spectroscopy Order (ring theory) techniques: high angular resolution Astronomy and Astrophysics Effective temperature Surface gravity Astrophysics - Solar and Stellar Astrophysics 13. Climate action Space and Planetary Science Astrophysics - Earth and Planetary Astrophysics brown dwarfs |
| DOI: | 10.48550/arxiv.1703.01023 |
| Popis: | The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of $\lesssim$30 AU, previously detected in high-contrast multi-band photometric observations. In order to better constrain the companion's physical characteristics, we acquired the first low-resolution ($R \sim 50$) near-infrared spectrum of it using the high-contrast hyperspectral imaging instrument Project 1640 on Palomar Observatory's 5-m Hale telescope. We obtained simultaneous images in 32 wavelength channels covering the $Y$, $J$, and $H$ bands ($\sim$952-1770 nm), and used data processing techniques based on principal component analysis to efficiently subtract chromatic background speckle-noise. GJ 758 B was detected in four epochs during 2013 and 2014. Basic astrometric measurements confirm its apparent northwest trajectory relative to the primary star, with no clear signs of orbital curvature. Spectra of SpeX/IRTF observed T dwarfs were compared to the combined spectrum of GJ 758 B, with ${\chi}^2$ minimization suggesting a best fit for spectral type T7.0$\pm$1.0, but with a shallow minimum over T5-T8. Fitting of synthetic spectra from the BT-Settl13 model atmospheres gives an effective temperature $T_{\text{eff}}=741 \pm 25$ K and surface gravity $\log g = 4.3 \pm 0.5$ dex (cgs). Our derived best-fit spectral type and effective temperature from modeling of the low-resolution spectrum suggest a slightly earlier and hotter companion than previous findings from photometric data, but do not rule out current results, and confirm GJ 758 B as one of the coolest sub-stellar companions to a Sun-like star to date. Comment: Accepted for publication in ApJ, 13 pages, 11 figures v2 updated with minor edits from corrected proofs |
| Databáze: | OpenAIRE |
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