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  • American Astronomical Society  (7)
  • Michalik, Daniel  (7)
  • 1
    Online Resource
    Online Resource
    The First Dynamical Mass Measurement in the HR 8799 System
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Letters Vol. 915, No. 1 ( 2021-07-01), p. L16-
    Details
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 915, No. 1 ( 2021-07-01), p. L16-
    Type of Medium: Online Resource
    ISSN: 2041-8205 , 2041-8213
    URL: Article
    DOI: 10.3847/2041-8213/ac0540
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 2006858-X
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    SCExAO/CHARIS Direct Imaging Discovery of a 20 au Separation, Low-mass Ratio Brown Dwarf Companion to an Accelerating Sun-like Star *
    American Astronomical Society ; 2020
    In:  The Astrophysical Journal Letters Vol. 904, No. 2 ( 2020-12-01), p. L25-
    Details
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 904, No. 2 ( 2020-12-01), p. L25-
    Abstract: We present the direct imaging discovery of a substellar companion to the nearby Sun-like star, HD 33632 Aa, at a projected separation of ∼20 au, obtained with SCExAO/CHARIS integral field spectroscopy complemented by Keck/NIRC2 thermal infrared imaging. The companion, HD 33632 Ab, induces a 10.5 σ astrometric acceleration on the star as detected with the Gaia and Hipparcos satellites. SCExAO/CHARIS JHK (1.1–2.4 μ m) spectra and Keck/NIRC2 L p (3.78 μ m) photometry are best matched by a field L/T transition object: an older, higher-gravity, and less dusty counterpart to HR 8799 cde. Combining our astrometry with Gaia/Hipparcos data and archival Lick Observatory radial velocities, we measure a dynamical mass of 46.4 ± 8 M J and an eccentricity of e 〈 0.46 at 95% confidence. HD 33632 Ab’s mass and mass ratio (4.0% ± 0.7%) are comparable to the low-mass brown dwarf GJ 758 B and intermediate between the more massive brown dwarf HD 19467 B and the (near-)planet-mass companions to HR 2562 and GJ 504. Using Gaia to select for direct imaging observations with the newest extreme adaptive optics systems can reveal substellar or even planet-mass companions on solar system–like scales at an increased frequency compared to blind surveys.
    Type of Medium: Online Resource
    ISSN: 2041-8205 , 2041-8213
    URL: Article
    DOI: 10.3847/2041-8213/abc631
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2020
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 2006858-X
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  • 3
    Online Resource
    Online Resource
    orvara: An Efficient Code to Fit Orbits Using Radial Velocity, Absolute, and/or Relative Astrometry
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 162, No. 5 ( 2021-11-01), p. 186-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 162, No. 5 ( 2021-11-01), p. 186-
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac042e
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207625-6
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
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  • 4
    Online Resource
    Online Resource
    A Dynamical Mass of 70 ± 5 M Jup for Gliese 229B, the First T Dwarf
    American Astronomical Society ; 2020
    In:  The Astronomical Journal Vol. 160, No. 4 ( 2020-10-01), p. 196-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 160, No. 4 ( 2020-10-01), p. 196-
    Abstract: We combine Keck/HIRES radial velocities, imaging with HiCIAO/Subaru and the Hubble Space Telescope, and absolute astrometry from Hipparcos and Gaia to measure a dynamical mass of 70 ± 5 for the brown dwarf companion to Gl 229. Gl 229B was the first imaged brown dwarf to show clear signs of methane in its atmosphere. Cooling models have been used to estimate a mass in the range of 20–55 , much lower than our measured value. We argue that our high dynamical mass is unlikely to be due to perturbations from additional unseen companions or to Gl 229B itself being a binary, and we find no evidence of a previously claimed radial velocity planet around Gl 229A. Future Gaia data releases will confirm the reliability of the absolute astrometry, though the data pass all quality checks in both Hipparcos and Gaia. Our dynamical mass implies a very old age for Gl 229, in some tension with kinematic and activity age indicators, and/or shortcomings in brown dwarf cooling models. Gl 229B joins a small but growing list of T dwarfs with masses approaching the minimum mass for core hydrogen ignition.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/abb45e
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2020
    detail.hit.zdb_id: 2207625-6
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Precise Dynamical Masses and Orbital Fits for β Pic b and β Pic c
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 161, No. 4 ( 2021-04-01), p. 179-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 161, No. 4 ( 2021-04-01), p. 179-
    Abstract: We present a comprehensive orbital analysis to the exoplanets β Pictoris b and c that resolves previously reported tensions between the dynamical and evolutionary mass constraints on β Pic b. We use the Markov Chain Monte Carlo orbit code orvara to fit 15 years of radial velocities and relative astrometry (including recent GRAVITY measurements), absolute astrometry from Hipparcos and Gaia, and a single relative radial velocity measurement between β Pic A and b. We measure model-independent masses of M Jup for β Pic b and 8.3 ± 1.0 M Jup for β Pic c. These masses are robust to modest changes to the input data selection. We find a well-constrained eccentricity of 0.119 ± 0.008 for β Pic b, and an eccentricity of for β Pic c, with the two orbital planes aligned to within ∼05. Both planets’ masses are within ∼1 σ of the predictions of hot-start evolutionary models and exclude cold starts. We validate our approach on N -body synthetic data integrated using REBOUND . We show that orvara can account for three-body effects in the β Pic system down to a level ∼5 times smaller than the GRAVITY uncertainties. Systematics in the masses and orbital parameters from orvara ’s approximate treatment of multiplanet orbits are a factor of ∼5 smaller than the uncertainties we derive here. Future GRAVITY observations will improve the constraints on β Pic c’s mass and (especially) eccentricity, but improved constraints on the mass of β Pic b will likely require years of additional radial velocity monitoring and improved precision from future Gaia data releases.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/abdc2e
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207625-6
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    htof: A New Open-source Tool for Analyzing Hipparcos, Gaia, and Future Astrometric Missions
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 162, No. 6 ( 2021-12-01), p. 230-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 162, No. 6 ( 2021-12-01), p. 230-
    Abstract: We present htof , an open-source tool for interpreting and fitting the intermediate astrometric data (IAD) from both the 1997 and 2007 reductions of Hipparcos, the scanning law of Gaia, and future missions such as the Nancy Grace Roman Space Telescope (NGRST). htof solves the astrometric parameters of any system for any arbitrary combination of absolute astrometric missions. In preparation for later Gaia data releases, htof supports arbitrarily high-order astrometric solutions (e.g., five-, seven-, and nine-parameter fits). Using htof , we find that the IAD of 6617 sources in Hipparcos 2007 might have been affected by a data corruption issue. htof integrates an ad hoc correction that reconciles the IAD of these sources with their published catalog solutions. We developed htof to study masses and orbital parameters of substellar companions, and we outline its implementation in one orbit fitting code ( orvara ). We use htof to predict a range of hypothetical additional planets in the β Pic system, which could be detected by coupling NGRST astrometry with Gaia and Hipparcos. htof is pip installable and available at https://github.com/gmbrandt/htof .
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac12d0
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207625-6
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
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    Online Resource
  • 7
    Online Resource
    Online Resource
    Precise Masses and Orbits for Nine Radial-velocity Exoplanets
    American Astronomical Society ; 2021
    In:  The Astronomical Journal Vol. 162, No. 6 ( 2021-12-01), p. 266-
    Details
    In: The Astronomical Journal, American Astronomical Society, Vol. 162, No. 6 ( 2021-12-01), p. 266-
    Abstract: Radial-velocity (RV) surveys have discovered hundreds of exoplanetary systems but suffer from a fundamental degeneracy between planet mass M p and orbital inclination i . In this paper, we resolve this degeneracy by combining RVs with complementary absolute astrometry taken from the Gaia EDR3 version of the cross calibrated Hipparcos–Gaia Catalog of Accelerations (HGCA). We use the Markov Chain Monte Carlo orbit code orvara to simultaneously fit literature RVs and absolute astrometry from the HGCA. We constrain the orbits, masses, and inclinations of nine single and massive RV companions orbiting nearby G and K stars. We confirm the planetary nature of six companions: HD 29021 b ( 4.47 − 0.65 + 0.67 M Jup ), HD 81040 b ( 7.24 − 0.37 + 1.0 M Jup ), HD 87883 b ( 6.31 − 0.32 + 0.31 M Jup ), HD 98649 b ( 9.7 − 1.9 + 2.3 M Jup ), HD 106252 b ( 10.00 − 0.73 + 0.78 M Jup ), and HD 171238 b ( 8.8 − 1.3 + 3.6 M Jup ). We place one companion, HD 196067 b ( 12.5 − 1.8 + 2.5 M Jup ) on the planet–brown dwarf boundary and two companions in the low-mass brown dwarf regime: HD 106515 Ab ( 18.9 − 1.4 + 1.5 M Jup ), and HD 221420 b ( 20.6 − 1.6 + 2.0 M Jup ). The brown dwarf HD 221420 b, with a semimajor axis of 9.99 − 0.70 + 0.74 au, a period of 27.7 − 2.5 + 3.0 yr, and an eccentricity of 0.162 − 0.030 + 0.035 represents a promising target for high-contrast imaging. The RV orbits of HD 87883 b, HD 98649 b, HD 171238 b, and HD 196067 b are not fully constrained yet because of insufficient RV data. We find two possible inclinations for each of these orbits due to difficulty in separating prograde from retrograde orbits, but we expect this will change decisively with future Gaia data releases.
    Type of Medium: Online Resource
    ISSN: 0004-6256 , 1538-3881
    URL: Article
    DOI: 10.3847/1538-3881/ac27ab
    RVK:
    US 1090
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207625-6
    detail.hit.zdb_id: 2003104-X
    SSG: 16,12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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