Jessica Ryan Lu

PLANETS AROUND LOW-MASS STARS (PALMS). VI. DISCOVERY OF A REMARKABLY RED PLANETARY-MASS COMPANION TO THE AB DOR MOVING GROUP CANDIDATE 2MASS J22362452+4751425*

We report the discovery of an extremely red planetary-mass companion to 2MASS J22362452+4751425, a ≈0.6 M⊙ late-K dwarf likely belonging to the ~120 Myr AB Doradus moving group. 2M2236+4751 b was identified in multi-epoch NIRC2 adaptive optics imaging at Keck Observatory at a separation of 3.”7, or 230 ± 20 AU in projection at the kinematic distance of 63 ± 5 pc to its host star. Assuming membership in the AB Dor group, as suggested from its kinematics, the inferred mass of 2M2236+4751 b is 11–14 M_(Jup). Follow-up Keck/OSIRIS K-band spectroscopy of the companion reveals strong CO absorption similar to other faint red L dwarfs and lacks signs of methane absorption, despite having an effective temperature of ≈900–1200 K. With a (J–K)_(MKO) color of 2.69 ± 0.12 mag, the near-infrared slope of 2M2236+4751 b is redder than all of the HR 8799 planets and instead resembles the ≈23 Myr isolated planetary-mass object PSO J318.5–22, implying that similarly thick photospheric clouds can persist in the atmospheres of giant planets at ages beyond 100 Myr. In near-infrared color–magnitude diagrams, 2M2236+4751 b is located at the tip of the red L dwarf sequence and appears to define the elbow of the AB Dor substellar isochrone separating low-gravity L dwarfs from the cooler young T dwarf track. 2M2236+4751 b is the reddest substellar companion to a star and will be a valuable benchmark to study the shared atmospheric properties of young low-mass brown dwarfs and extrasolar giant planets.

Investigating the Binarity of S0-2: Implications for Its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole

The star S0-2, which orbits the supermassive black hole (SMBH) in our Galaxy with a period of 16 years, provides the strongest constraint on both the mass of the SMBH and the distance to the Galactic center. S0-2 will soon provide the first measurement of relativistic effects near a SMBH. We report the first limits on the binarity of S0-2 from radial velocity monitoring, which has implications for both understanding its origin and robustness as a probe of the central gravitational field. With 87 radial velocity measurements, which include 12 new observations presented, we have the data set to look for radial velocity variations from S0-2s orbital model. Using a Lomb-Scargle analysis and orbit fitting for potential binaries, we detect no radial velocity variation beyond S0-2s orbital motion and do not find any significant periodic signal. The lack of a binary companion does not currently distinguish between different formation scenarios for S0-2. The upper limit on the mass of a companion star (

A SEARCH FOR STELLAR-MASS BLACK HOLES VIA ASTROMETRIC MICROLENSING

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Precision astrometry with adaptive optics: constraints on the mutual orbit of Luhman 16AB from GeMS

) still allowed by our results has a median upper limit of

Super-solar Metallicity Stars in the Galactic Center Nuclear Star Cluster: Unusual Sc, V, and Y Abundances

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Massive Young Clusters Near the Galactic Center

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Off-axis PSF reconstruction for integral field spectrograph: instrumental aberrations and application to Keck/OSIRIS data

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Point-spread function reconstruction for integral-field spectrograph data

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Observational constraints on the formation and evolution of the Milky Way nuclear star cluster with Keck and Gemini

for periods between 1 and 150 days, the longest period to avoid tidal break up of the binary. We also investigate the impact of the remaining allowed binary system on the measurement of the relativistic redshift at S0-2s closest approach in 2018. While binary star systems are important to consider for this experiment, we find plausible binaries for S0-2 will not alter a 5