Characterization of HD 206893 B from Near- to Thermal-infrared

Meshkat, Tiffany; Lee, Eve J.; Mawet, Dimitri; Choquet, Élodie; Ygouf, Marie; Patel, Rahul; Ruane, Garreth; Wang, Jason; Wallack, Nicole L.; Absil, Olivier; Beichman, Charles

doi:10.3847/1538-4357/ac09ed

Cited by 3 publications

(5 citation statements)

References 46 publications

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“…More details on the orbit fitting, including the orbital alignment parameters (e.g., i, ω, and Ω) can be found in Appendix A. Similar to the case for HD 206893c, the mass determination for HD 206893B is consistent with, but also significantly more precise than, previous estimates (e.g., Grandjean et al 2019a;Meshkat et al 2021;Ward-Duong et al 2021;Kammerer et al 2021) that quoted a mass of 5-30 M Jup , and clearly places HD 206893B in the low-mass BD regime.…”

Section: Orbital Fitssupporting

confidence: 71%

“…However, this was later refined to be between ∼5 M Jup (Kammerer et al 2021) and 30−40 M Jup (Delorme et al 2017;Kammerer et al 2021;Ward-Duong et al 2021). This object possesses extraordinarily red infrared colors and has been characterized in numerous subsequent works (Delorme et al 2017;Stolker et al 2020;Meshkat et al 2021;Ward-Duong et al 2021;Kammerer et al 2021).…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Direct discovery of the inner exoplanet in the HD 206893 system

Hinkley¹,

Lacour²,

Marleau³

et al. 2023

A&A

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Aims. HD 206893 is a nearby debris disk star that hosts a previously identified brown dwarf companion with an orbital separation of ∼10 au. Long-term precise radial velocity (RV) monitoring, as well as anomalies in the system proper motion, has suggested the presence of an additional, inner companion in the system. Methods. Using information from ongoing precision RV measurements with the HARPS spectrograph, as well as Gaia host star astrometry, we have undertaken a multi-epoch search for the purported additional planet using the VLTI/GRAVITY instrument. Results. We report a high-significance detection over three epochs of the companion HD 206893c, which shows clear evidence for Keplerian orbital motion. Our astrometry with ∼50−100 μarcsec precision afforded by GRAVITY allows us to derive a dynamical mass of 12.7$ ^{+1.2}_{-1.0} $MJup and an orbital separation of 3.53$ ^{+0.08}_{-0.06} $ au for HD 206893c. Our fits to the orbits of both companions in the system use both Gaia astrometry and RVs to also provide a precise dynamical estimate of the previously uncertain mass of the B component, and therefore allow us to derive an age of 155 ± 15 Myr for the system. We find that theoretical atmospheric and evolutionary models that incorporate deuterium burning for HD 206893c, parameterized by cloudy atmosphere models as well as a “hybrid sequence” (encompassing a transition from cloudy to cloud-free), provide a good simultaneous fit to the luminosity of both HD 206893B and c. Thus, accounting for both deuterium burning and clouds is crucial to understanding the luminosity evolution of HD 206893c. Conclusions. In addition to using long-term RV information, this effort is an early example of a direct imaging discovery of a bona fide exoplanet that was guided in part by Gaia astrometry. Utilizing Gaia astrometry is expected to be one of the primary techniques going forward for identifying and characterizing additional directly imaged planets. In addition, HD 206893c is an example of an object narrowly straddling the deuterium-burning limit but unambiguously undergoing deuterium burning. Additional discoveries like this may therefore help clarify the discrimination between a brown dwarf and an extrasolar planet. Lastly, this discovery is another example of the power of optical interferometry to directly detect and characterize extrasolar planets where they form, at ice-line orbital separations of 2−4 au.

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Section: Orbital Fitssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 96%

Direct discovery of the inner exoplanet in the HD 206893 system

Hinkley¹,

Lacour²,

Marleau³

et al. 2023

A&A

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“…We note that none of these companions have (J − K ) MKO or J MKO − W2 colors as red as CWISE J0506+0738. Of the remaining planetary-mass companions that lack 3-5 μm photometry, only 2M1207b (J − K = 3.07 ± 0.23 mag; Chauvin et al 2004Chauvin et al , 2005Mohanty et al 2007;Patience et al 2010) and HD 206893B (J − K = 3.36 ± 0.08 mag; Delorme et al 2017;Milli et al 2017;Kammerer et al 2021;Meshkat et al 2021;Ward-Duong et al 2021) have redder J − K colors than CWISE J0506+0738.…”

Section: Redder Than Redmentioning

confidence: 99%

“…The vast majority of the current population of directly imaged planetary-mass companions are also young and have similar effective temperatures, masses, and radii to young L dwarfs, as well as observed properties, including unusually red near-infrared colors. Examples include 2M1207b (Chauvin et al 2004(Chauvin et al , 2005Patience et al 2010), HD 206893B (Delorme et al 2017;Milli et al 2017;Kammerer et al 2021;Meshkat et al 2021;Ward-Duong et al 2021), VHS J125601.92 −125723.9B (Gauza et al 2015), 2MASS J22362452 +4751425b (Bowler et al 2017), BD+60 1417B (Faherty et al 2021), HR8799bcd (Marois et al 2008), and HD 203030B . Young, red L dwarfs in the field provide an opportunity to study the physical properties of giant exoplanet-like atmospheres without the technical challenge of blocking host starlight.…”

Section: Introductionmentioning

confidence: 99%

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

Schneider

Burgasser

Bruursema

et al. 2023

ApJL

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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 free-floating 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 CH4 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 multiepoch 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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“…The vast majority of the current population of directly-imaged planetary-mass companions are also young and have similar effective temperatures, masses, and radii as young L dwarfs, as well as observed properties, including unusually red near-infrared colors. Examples include 2M1207b (Chauvin et al 2004(Chauvin et al , 2005Patience et al 2010), HD 206893B (Milli et al 2017;Delorme et al 2017;Kammerer et al 2021;Meshkat et al 2021;Ward-Duong et al 2021), VHS J125601.92−125723.9B (Gauza et al 2015), 2MASS J22362452+4751425b (Bowler et al 2017), BD+60 1417B (Faherty et al 2021), HR8799bcd (Marois et al 2008), and HD 203030B (Metchev & Hillenbrand 2006). Young, red L dwarfs in the field provide an opportunity to study the physical properties of giant exoplanet-like atmospheres without the technical challenge of blocking host star light.…”

Section: Introductionmentioning

confidence: 99%

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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Characterization of HD 206893 B from Near- to Thermal-infrared

Cited by 3 publications

References 46 publications

Direct discovery of the inner exoplanet in the HD 206893 system

Direct discovery of the inner exoplanet in the HD 206893 system

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

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

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