The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b

Miles, Brittany; Biller, Beth; Patapis, Polychronis; Worthen, Kadin; Rickman, E. L.; Hoch, Kielan K. W.; Skemer, Andrew J.; Perrin, Marshall D.; Chen, Christine; Mukherjee, Sagnick; Morley, Caroline; Moran, Sarah E.; Petrus, Simon; Carter, Aarynn L.; Choquet, Élodie; Hinkley, Sasha; Ward-Duong, Kimberly; Leisenring, Jarron; Millar‐Blanchaer, Maxwell A.; Pueyo, Laurent; Ray, Shrishmoy; Stapelfeldt, Karl; Stone, Jordan; Wang, Jason; Absil, Olivier; Balmer, William O.; Boccaletti, A.; Bonavita, M.; Booth, Mark; Bowler, Brendan P.; Chauvin, G.; Christiaens, Valentin; Currie, Thayne; Danielski, Camilla; Fortney, Jonathan J.; Girard, Julien; Greenbaum, Alexandra Z.; Henning, Thomas; Hines, Dean C.; Janson, Markus; Kalas, Paul; Kammerer, Jens; Kenworthy, Matthew A.; Kervella, P.; Lagage, Pierre-Olivier; Lew, Ben W. P.; Liu, Mengmeng; Macintosh, Bruce; Marino, Sebastián; Marley, Mark S.; Marois, Christian; Matthews, Elisabeth C.; Matthews, Brenda C.; Mawet, Dimitri; McElwain, Michael W.; Metchev, Stanimir; Meyer, Michael; Mollière, P.; Pantin, E.; Rebollido, Andreas Quirrenbachm Isabel; Ren, Bin; Vasist, Malavika; Wyatt, M. C.; Zhou, Yifan; Briesemeister, Zackery; Bryan, M.; Calissendorff, Per; Catalloube, Faustine; Cugno, Gabriele; Furio, Matthew De; Dupuy, Trent J.; Factor, Samuel M.; Faherty, Jacqueline K.; Fitzgerald, Michael P.; Franson, Kyle; Gonzales, Eileen C.; Hood, Callie E.; Howe, Alex R.; Kraus, Adam L.; Kuzuhara, Masayuki; Lawson, Kellen; Lazzoni, C.; Liu, Pengyu; Llop-Sayson, Jorge; Lloyd, James P.; Martinez, Raquel A.; Mazoyer, J.; Quanz, Sascha P.; Redai, Jea Adams; Samland, M.; Schlieder, Joshua E.; Tamura, Motohide; Tan, Xianyu; Uyama, Taichi; Vigan, A.; Vos, Johanna M.; Wagner, Kevin; Wolff, Schuyler; Ygouf, Marie; Zhang, Keming; Zhang, Zhoujian

doi:10.48550/arxiv.2209.00620

Cited by 8 publications

(12 citation statements)

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“…Objects with low surface gravities have inefficient gravitational settling of silicate dust grains, which can remain high in the atmospheres. Such grains can be directly detected at long wavelengths (e.g., Cushing et al 2006;Burgasser et al 2008;Suárez & Metchev 2022) and could be constrained for CWISE J0506+0738 with future long-wavelength observations (e.g., Miles et al 2022). The angle at which a brown dwarf is viewed has also been shown to affect its near-infrared colors, with objects viewed equator-on tending to have redder colors than those viewed pole-on (Vos et al 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Because of this object's unique spectroscopic properties, and the fact that young brown dwarfs often display large-amplitude variability (e.g., Vos et al 2022a), CWISE J0506+0738 is an intriguing target for future photometric or spectroscopic variability monitoring. Longer wavelength observations with the James Webb Space Telescope would have the additional advantage of further constraining the existence and abundance of CH 4 and analyzing the presence and properties of dust grains through silicate absorption features (Miles et al 2022).…”

Section: Discussionmentioning

confidence: 99%

“…The characterization of brown dwarfs and planetary mass objects as "low surface gravity" or "young" typically arises from gravity-sensitive (or more specifically, photosphere pressure-sensitive) spectral features quantified by spectral indices (e.g., Steele & Jameson 1995;Martin et al 1996;Luhman et al 1997;Gorlova et al 3 Recent high S/N JWST/NIRSPEC observations of VHS 1256−1257B have revealed the presence of weak 1.6 µm absorption in its spectrum (Miles et al 2022).…”

Section: Spectral Evidence Of Youthmentioning

confidence: 99%

“…Another spectral feature that has been used to distinguish low-surface gravity late-L dwarfs are the K I absorption lines between 1.1 and 1.3 µm (McGovern et al 2004;Allers & Liu 2013;Miles et al 2022). Our Keck/NIRES spectrum does not have sufficient S/N around the J-band peak to investigate these lines.…”

Section: Spectral Evidence Of Youthmentioning

confidence: 99%

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Redder than Red: Discovery of an Exceptionally Red L/T Transition Dwarf

Schneider¹,

Burgasser²,

Bruursema³

et al. 2023

Preprint

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We present the discovery of CWISE J050626.96+073842.4 (CWISE J0506+0738), an L/T transition dwarf with extremely red near-infrared colors discovered through the Backyard Worlds: Planet 9 citizen science project. Photometry from UKIRT and CatWISE give a (J − K) MKO color of 2.97±0.03 mag and a J MKO −W2 color of 4.93±0.02 mag, making CWISE J0506+0738 the reddest known freefloating L/T dwarf in both colors. We confirm the extremely red nature of CWISE J0506+0738 using Keck/NIRES near-infrared spectroscopy and establish that it is a low-gravity late-type L/T transition dwarf. The spectrum of CWISE J0506+0738 shows possible signatures of CH 4 absorption in its atmosphere, suggesting a colder effective temperature than other known, young, red L dwarfs. We assign a preliminary spectral type for this source of L8γ-T0γ. We tentatively find that CWISE J0506+0738 is variable at 3-5 µm based on multi-epoch WISE photometry. Proper motions derived from follow-up UKIRT observations combined with a radial velocity from our Keck/NIRES spectrum and a photometric distance estimate indicate a strong membership probability in the β Pic moving group. A future parallax measurement will help to establish a more definitive moving group membership for this unusual object.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Spectral Evidence Of Youthmentioning

confidence: 99%

Section: Spectral Evidence Of Youthmentioning

confidence: 99%

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Redder than Red: Discovery of an Exceptionally Red L/T Transition Dwarf

Schneider¹,

Burgasser²,

Bruursema³

et al. 2023

Preprint

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“…However, there is evidence that brown dwarf variability amplitude may have a a strong wavelength dependence. For example, HST observations of highly variable L dwarf companion VHS 1256-1257 b identified a large variability amplitude of 24.7% at 1.27 µm, while Spitzer observations at 4.5 µm found a far lower amplitude of 5.76±0.04% (Bowler et al 2020b;Zhou et al 2020b;Miles et al 2022). Zhou et al (2020b) do note, however, that the HST and Spitzer observations were not obtained contemporaneously and so the atmosphere of VHS 1256-1257 b and hence its variability properties are likely to have changed substantially over the intervening timescale.…”

Section: Variability Interpretationmentioning

confidence: 99%

Measuring the variability of directly imaged exoplanets using vector Apodizing Phase Plates combined with ground-based differential spectrophotometry

Sutlieff¹,

Birkby²,

Stone³

et al. 2023

Preprint

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Clouds and other features in exoplanet and brown dwarf atmospheres cause variations in brightness as they rotate in and out of view. Ground-based instruments reach the high contrasts and small inner working angles needed to monitor these faint companions, but their small fieldsof-view lack simultaneous photometric references to correct for non-astrophysical variations. We present a novel approach for making ground-based light curves of directly imaged companions using high-cadence differential spectrophotometric monitoring, where the simultaneous reference is provided by a double-grating 360°vector Apodizing Phase Plate (dgvAPP360) coronagraph. The dgvAPP360 enables high-contrast companion detections without blocking the host star, allowing it to be used as a simultaneous reference. To further reduce systematic noise, we emulate exoplanet transmission spectroscopy, where the light is spectrally-dispersed and then recombined into white-light flux. We do this by combining the dgvAPP360 with the infrared ALES integral field spectrograph on the Large Binocular Telescope Interferometer. To demonstrate, we observed the red companion HD 1160 B (separation ∼780 mas) for one night, and detect 8.8% semi-amplitude sinusoidal variability with a ∼3.24 h period in its detrended white-light curve. We achieve the greatest precision in ground-based high-contrast imaging light curves of sub-arcsecond companions to date, reaching 3.7% precision per 18-minute bin. Individual wavelength channels spanning 3.59-3.99 µm further show tentative evidence of increasing variability with wavelength. We find no evidence yet of a systematic noise floor, hence additional observations can further improve the precision. This is therefore a promising avenue for future work aiming to map storms or find transiting exomoons around giant exoplanets.

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X-SHYNE: X-shooter spectra of young exoplanet analogs

Petrus

Chauvin

Bonnefoy

et al. 2023

A&A

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We present simultaneous 0.65–2.5 μm medium resolution (3300 ≤ Rλ ≤ 8100) VLT/X-shooter spectra of the relatively young (150–300 Myr) low-mass (19 ± 5MJup) L–T transition object VHS 1256−1257 b, a known spectroscopic analog of HR8799d. The companion is a prime target for the JWST Early Release Science (ERS) and one of the highest-amplitude variable brown dwarfs known to date. We compare the spectrum to the custom grids of cloudless ATMO models, exploring the atmospheric composition with the Bayesian inference tool ForMoSA. We also reanalyze low-resolution HST/WFC3 1.10–1.67 μm spectra at minimum and maximum variability to contextualize the X-shooter data interpretation. The models reproduce the slope and most molecular absorption from 1.10 to 2.48 μm self-consistently, but they fail to provide a radius and a surface gravity consistent with evolutionary model predictions. They do not reproduce the optical spectrum and the depth of the K I doublets in the J band consistently. We derived Teff = 1380±54 K, log(g) = 3.97±0.48 dex, [M/H] = 0.21±0.29, and C/O > 0.63. Our inversion of the HST/WFC3 spectra suggests a relative change of $ 27^{+6}_{-5} $ K of the disk-integrated Teff correlated with the near-infrared brightness. Our data anchor the characterization of that object in the near-infrared and could be used jointly to the ERS mid-infrared data to provide the most detailed characterization of an ultracool dwarf to date.

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The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b

Cited by 8 publications

References 0 publications

Redder than Red: Discovery of an Exceptionally Red L/T Transition Dwarf

Redder than Red: Discovery of an Exceptionally Red L/T Transition Dwarf

Measuring the variability of directly imaged exoplanets using vector Apodizing Phase Plates combined with ground-based differential spectrophotometry

X-SHYNE: X-shooter spectra of young exoplanet analogs

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