The JWST NIRSpec integral field unit (IFU) presents a unique opportunity to observe directly imaged exoplanets from 3 to 5 μm at moderate spectral resolution (R ∼ 2700) and thereby better constrain the composition, disequilibrium chemistry, and cloud properties of their atmospheres. In this work, we present the first NIRSpec IFU high-contrast observations of a substellar companion that requires starlight suppression techniques. We develop specific data-reduction strategies to study faint companions around bright stars and assess the performance of NIRSpec at high contrast. First, we demonstrate an approach to forward model the companion signal and the starlight directly in the detector images, which mitigates the effects of NIRSpec's spatial undersampling. We demonstrate a sensitivity to planets that are 3 × 10−6 fainter than their stars at 1'', or 3 × 10−5 at 03. Then, we implement a reference star point-spread function subtraction and a spectral extraction that does not require spatially and spectrally regularly sampled spectral cubes. This allows us to extract a moderate resolution (R ∼ 2,700) spectrum of the faint T dwarf companion HD 19467 B from 2.9 to 5.2 μm with a signal-to-noise ratio of ∼10 per resolution element. Across this wavelength range, HD 19467 B has a flux ratio varying between 10−5 and 10−4 and a separation relative to its star of 16. A companion paper by Hoch et al. more deeply analyzes the atmospheric properties of this companion based on the extracted spectrum. Using the methods developed here, NIRSpec's sensitivity may enable direct detection and spectral characterization of relatively old (∼1 Gyr), cool (∼250 K), and closely separated (∼3–5 au) exoplanets that are less massive than Jupiter.
JWST-TST High Contrast: Achieving Direct Spectroscopy of Faint Substellar Companions Next to Bright Stars with the NIRSpec Integral Field Unit
- Creators
- Ruffio, Jean-Baptiste
- Perrin, Marshall D.
- Hoch, Kielan K. W.
- Kammerer, Jens
- Konopacky, Quinn M.
- Pueyo, Laurent
- Madurowicz, Alex
- Rickman, Emily
- Theissen, Christopher A.
- Agrawal, Shubh
- Greenbaum, Alexandra Z.
- Miles, Brittany E.
- Barman, Travis S.
- Balmer, William O.
- Llop-Sayson, Jorge
- Girard, Julien H.
- Rebollido, Isabel
- Soummer, Rémi
- Allen, Natalie H.
- Anderson, Jay
- Beichman, Charles A.
- Bellini, Andrea
- Bryden, Geoffrey
- Espinoza, Néstor
- Glidden, Ana
- Huang, Jingcheng
- Lewis, Nikole K.
- Libralato, Mattia
- Louie, Dana R.
- Sohn, Sangmo Tony
- Seager, Sara
- van der Marel, Roeland P.
- Wakeford, Hannah R.
- Watkins, Laura L.
- Ygouf, Marie
- Mountain, C. Matt
Abstract
Acknowledgement
© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
This paper reports work carried out in the context of the JWST Telescope Scientist Team (https://www.stsci.edu/~marel/jwsttelsciteam.html; PI: M. Mountain). Funding is provided to the team by NASA through grant 80NSSC20K0586. Based on observations with the NASA/ESA/CSA JWST, associated with program GTO-1414 (PI: Marshall Perrin), obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-03127.
Material presented in this work is supported by the National Aeronautics and Space Administration under grants/contracts/agreements No. 80NSSC21K0573 (J.-B.R., Q.M.K., T.S.B., and K.K.W.) issued through the Astrophysics Division of the Science Mission Directorate. Any opinions, findings, and conclusions or recommendations expressed in this work are those of the author(s) and do not necessarily reflect the views of the National Aeronautics and Space Administration. This work benefited from NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. A.G. acknowledges support from the Robert R. Shrock Graduate Fellowship. D.R.L.'s research activities were supported by an appointment to the NASA Postdoctoral Program at the NASA Goddard Space Flight Center, administered by Oak Ridge Associated Universities under contract with NASA. N.H.A. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant No. DGE1746891. This work was authored by employees of Caltech/IPAC under Contract No. 80GSFC21R0032 with the National Aeronautics and Space Administration.
This research has made use of the SVO Filter Profile Service (http://svo2.cab.inta-csic.es/theory/fps/) supported by the Spanish MINECO through grant AYA2017-84089.
Facilities
JWST - James Webb Space Telescope (NIRSpec); JWST - James Webb Space Telescope (NIRCam)
Software References
Python, numpy (Harris et al. 2020), scipy (Virtanen et al. 2020), Matplotlib (Hunter 2007), astropy (Astropy Collaboration et al. 2013), pandas (pandas development team 2023), h5py, 35 mkl, PyAstronomy (Czesla et al. 2019), astroquery (Ginsburg et al. 2019), multiprocessing, whereistheplanet 36 (Wang et al. 2021a), jwst (Bushouse et al. 2023), webbpsf (Perrin et al. 2012, 2014), stdatamodels, SpaceKLIP (Kammerer et al. 2022), BREADS 37 (Ruffio et al. 2021; Agrawal et al. 2023), ChatGPT 3.5 38 (for minor coding suggestions)
Files
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Additional details
- ISSN
- 1538-3881
- National Aeronautics and Space Administration
- 80NSSC20K0586
- National Aeronautics and Space Administration
- NAS 5-03127
- National Aeronautics and Space Administration
- 80NSSC21K0573
- National Aeronautics and Space Administration
- NASA Postdoctoral Fellowship
- National Science Foundation
- NSF Graduate Research Fellowship DGE-1746891
- National Aeronautics and Space Administration
- 80GSFC21R0032
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)