Project 1640 Observations of Brown Dwarf GJ 758 B

Near-infrared Spectrum and Atmospheric Modeling

R. Nilsson, A. Veicht, P. A.Giorla Godfrey, E. L. Rice, J. Aguilar, L. Pueyo, L. C. Roberts, R. Oppenheimer, D. Brenner, S. H. Luszcz-Cook, E. Bacchus, C. Beichman, R. Burruss, E. Cady, R. Dekany, Robert Fergus, L. Hillenbrand, S. Hinkley, D. King, T. Lockhart & 6 others I. R. Parry, A. Sivaramakrishnan, R. Soummer, G. Vasisht, C. Zhai, N. T. Zimmerman

Research output: Contribution to journalArticle

Abstract

The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of ≲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 ∼ 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 (∼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 χ 2 minimization suggesting a best fit for spectral type T7.0 ±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 eff = 741 ±25 K and surface gravity 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.

Original languageEnglish (US)
Article number64
JournalAstrophysical Journal
Volume838
Issue number1
DOIs
StatePublished - Mar 20 2017

Fingerprint

atmospheric modeling
near infrared
infrared spectra
stars
sun
principal components analysis
speckle
observatories
coverings
time measurement
curvature
trajectories
telescopes
gravitation
principal component analysis
atmospheres
orbitals
observatory
optimization
temperature

Keywords

  • brown dwarfs
  • instrumentation: adaptive optics
  • instrumentation: spectrographs
  • planets and satellites: detection
  • stars: individual (GJ 758)
  • techniques: high angular resolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Nilsson, R., Veicht, A., Godfrey, P. A. G., Rice, E. L., Aguilar, J., Pueyo, L., ... Zimmerman, N. T. (2017). Project 1640 Observations of Brown Dwarf GJ 758 B: Near-infrared Spectrum and Atmospheric Modeling. Astrophysical Journal, 838(1), [64]. https://doi.org/10.3847/1538-4357/aa643c

Project 1640 Observations of Brown Dwarf GJ 758 B : Near-infrared Spectrum and Atmospheric Modeling. / Nilsson, R.; Veicht, A.; Godfrey, P. A.Giorla; Rice, E. L.; Aguilar, J.; Pueyo, L.; Roberts, L. C.; Oppenheimer, R.; Brenner, D.; Luszcz-Cook, S. H.; Bacchus, E.; Beichman, C.; Burruss, R.; Cady, E.; Dekany, R.; Fergus, Robert; Hillenbrand, L.; Hinkley, S.; King, D.; Lockhart, T.; Parry, I. R.; Sivaramakrishnan, A.; Soummer, R.; Vasisht, G.; Zhai, C.; Zimmerman, N. T.

In: Astrophysical Journal, Vol. 838, No. 1, 64, 20.03.2017.

Research output: Contribution to journalArticle

Nilsson, R, Veicht, A, Godfrey, PAG, Rice, EL, Aguilar, J, Pueyo, L, Roberts, LC, Oppenheimer, R, Brenner, D, Luszcz-Cook, SH, Bacchus, E, Beichman, C, Burruss, R, Cady, E, Dekany, R, Fergus, R, Hillenbrand, L, Hinkley, S, King, D, Lockhart, T, Parry, IR, Sivaramakrishnan, A, Soummer, R, Vasisht, G, Zhai, C & Zimmerman, NT 2017, 'Project 1640 Observations of Brown Dwarf GJ 758 B: Near-infrared Spectrum and Atmospheric Modeling', Astrophysical Journal, vol. 838, no. 1, 64. https://doi.org/10.3847/1538-4357/aa643c
Nilsson, R. ; Veicht, A. ; Godfrey, P. A.Giorla ; Rice, E. L. ; Aguilar, J. ; Pueyo, L. ; Roberts, L. C. ; Oppenheimer, R. ; Brenner, D. ; Luszcz-Cook, S. H. ; Bacchus, E. ; Beichman, C. ; Burruss, R. ; Cady, E. ; Dekany, R. ; Fergus, Robert ; Hillenbrand, L. ; Hinkley, S. ; King, D. ; Lockhart, T. ; Parry, I. R. ; Sivaramakrishnan, A. ; Soummer, R. ; Vasisht, G. ; Zhai, C. ; Zimmerman, N. T. / Project 1640 Observations of Brown Dwarf GJ 758 B : Near-infrared Spectrum and Atmospheric Modeling. In: Astrophysical Journal. 2017 ; Vol. 838, No. 1.
@article{1981e8f394a741bba354a4effab95fe2,
title = "Project 1640 Observations of Brown Dwarf GJ 758 B: Near-infrared Spectrum and Atmospheric Modeling",
abstract = "The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of ≲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 ∼ 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 (∼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 χ 2 minimization suggesting a best fit for spectral type T7.0 ±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 eff = 741 ±25 K and surface gravity 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.",
keywords = "brown dwarfs, instrumentation: adaptive optics, instrumentation: spectrographs, planets and satellites: detection, stars: individual (GJ 758), techniques: high angular resolution",
author = "R. Nilsson and A. Veicht and Godfrey, {P. A.Giorla} and Rice, {E. L.} and J. Aguilar and L. Pueyo and Roberts, {L. C.} and R. Oppenheimer and D. Brenner and Luszcz-Cook, {S. H.} and E. Bacchus and C. Beichman and R. Burruss and E. Cady and R. Dekany and Robert Fergus and L. Hillenbrand and S. Hinkley and D. King and T. Lockhart and Parry, {I. R.} and A. Sivaramakrishnan and R. Soummer and G. Vasisht and C. Zhai and Zimmerman, {N. T.}",
year = "2017",
month = "3",
day = "20",
doi = "10.3847/1538-4357/aa643c",
language = "English (US)",
volume = "838",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Project 1640 Observations of Brown Dwarf GJ 758 B

T2 - Near-infrared Spectrum and Atmospheric Modeling

AU - Nilsson, R.

AU - Veicht, A.

AU - Godfrey, P. A.Giorla

AU - Rice, E. L.

AU - Aguilar, J.

AU - Pueyo, L.

AU - Roberts, L. C.

AU - Oppenheimer, R.

AU - Brenner, D.

AU - Luszcz-Cook, S. H.

AU - Bacchus, E.

AU - Beichman, C.

AU - Burruss, R.

AU - Cady, E.

AU - Dekany, R.

AU - Fergus, Robert

AU - Hillenbrand, L.

AU - Hinkley, S.

AU - King, D.

AU - Lockhart, T.

AU - Parry, I. R.

AU - Sivaramakrishnan, A.

AU - Soummer, R.

AU - Vasisht, G.

AU - Zhai, C.

AU - Zimmerman, N. T.

PY - 2017/3/20

Y1 - 2017/3/20

N2 - The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of ≲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 ∼ 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 (∼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 χ 2 minimization suggesting a best fit for spectral type T7.0 ±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 eff = 741 ±25 K and surface gravity 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.

AB - The nearby Sun-like star GJ 758 hosts a cold substellar companion, GJ 758 B, at a projected separation of ≲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 ∼ 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 (∼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 χ 2 minimization suggesting a best fit for spectral type T7.0 ±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 eff = 741 ±25 K and surface gravity 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.

KW - brown dwarfs

KW - instrumentation: adaptive optics

KW - instrumentation: spectrographs

KW - planets and satellites: detection

KW - stars: individual (GJ 758)

KW - techniques: high angular resolution

UR - http://www.scopus.com/inward/record.url?scp=85016765002&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85016765002&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aa643c

DO - 10.3847/1538-4357/aa643c

M3 - Article

VL - 838

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 64

ER -