Mason G. MacDougall
A5077883242- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Planetary Science and Exploration
- History and Developments in Astronomy
- Astronomical Observations and Instrumentation
- Space Exploration and Technology
- Scientific Research and Discoveries
- Astronomical and nuclear sciences
- High-pressure geophysics and materials
- Satellite Image Processing and Photogrammetry
- Space Science and Extraterrestrial Life
- Remote Sensing and LiDAR Applications
- Archaeology and ancient environmental studies
- Spacecraft and Cryogenic Technologies
- Historical Astronomy and Related Studies
University of California, Los Angeles
2021-2024
Abstract In 2017, the California-Kepler Survey (CKS) published its first data release (DR1) of high-resolution optical spectra 1305 planet hosts. Refined CKS radii revealed that small planets are bifurcated into two distinct populations, super-Earths (smaller than 1.5 R ⊕ ) and sub-Neptunes (between 2.0 4.0 ), with few in between (the “radius gap”). Several theoretical models radius gap predict variation stellar mass, but testing these predictions is challenging DR1 due to limited M ⋆ range...
Convergent disk migration has long been suspected to be responsible for forming planetary systems with a chain of mean-motion resonances (MMR). Dynamical evolution over time could disrupt the delicate resonant configuration. We present TOI-1136, 700-Myr-old G star hosting at least 6 transiting planets between $\sim$2 and 5 $R_\oplus$. The orbital period ratios deviate from exact commensurability by only $10^{-4}$, smaller than $\sim$\,$10^{-2}$ deviations seen in typical Kepler near-resonant...
TOI-561 is a galactic thick disk star hosting an ultra-short period (0.45 day orbit) planet with radius of 1.37 R$_{\oplus}$, making it one the most metal-poor ([Fe/H] = -0.41) and oldest ($\sim$10 Gyr) sites where Earth-sized has been found. We present new simultaneous radial velocity measurements (RVs) from Gemini-N/MAROON-X Keck/HIRES, which we combined literature RVs to derive mass M$_{b}$=2.24 $\pm$ 0.20 M$_{\oplus}$. also used two Sectors TESS photometry improve determination, finding...
Abstract NASA’s Transiting Exoplanet Survey Satellite (TESS) mission promises to improve our understanding of hot Jupiters by providing an all-sky, magnitude-limited sample transiting suitable for population studies. Assembling such a requires confirming hundreds planet candidates with additional follow-up observations. Here we present 20 that were detected using TESS data and confirmed be planets through photometric, spectroscopic, imaging observations coordinated the Follow-up Observing...
Abstract Despite the importance of Jupiter and Saturn to Earth’s formation habitability, there has not yet been a comprehensive observational study how giant exoplanets correlate with architectural properties close-in, sub-Neptune-sized exoplanets. This is largely because transit surveys are particularly insensitive planets at orbital separations ≳1 au, so their census Jupiter-like incomplete, inhibiting our relationship between small that do transit. To investigate distant, planets, we...
Abstract The Kepler and TESS missions have demonstrated that planets are ubiquitous. However, the success of these heavily depends on ground-based radial velocity (RV) surveys, which combined with transit photometry can yield bulk densities orbital properties. While most host stars too faint for detailed follow-up observations, is detecting orbiting nearby bright more amenable to RV characterization. Here, we introduce TESS-Keck Survey (TKS), an program using ∼100 nights Keck/HIRES study...
In this study, we performed a homogeneous analysis of the planets around FGK dwarf stars observed by Kepler and K2 missions, providing spectroscopic parameters for 310 targets -- including 239 Scaling hosts with Keck/HIRES. For orbital periods less than 40 days, found that distribution as function period, stellar effective temperature, metallicity was consistent between Kepler, reflecting planet formation efficiency across numerous ~1 kpc sight-lines in local Milky Way. Additionally,...
Abstract The Transiting Exoplanet Survey Satellite (TESS) has discovered hundreds of new worlds, with TESS planet candidates now outnumbering the total number confirmed planets from Kepler. Owing to differences in survey design, continues provide that are better suited for subsequent follow-up studies, including mass measurement through radial velocity (RV) observations, compared Kepler targets. In this work, we present TESS-Keck Survey’s (TKS) Mass Catalog: a uniform analysis all TKS RV...
Abstract We present a radial velocity (RV) analysis of TOI-1136, bright Transiting Exoplanet Survey Satellite (TESS) system with six confirmed transiting planets, and seventh single-transiting planet candidate. All planets in the are amenable to transmission spectroscopy, making TOI-1136 one best targets for intra-system comparison exoplanet atmospheres. is young (∼700 Myr), exhibits transit timing variations (TTVs). The youth contributes high stellar variability on order 50 m s −1 , much...
We report the discovery of TOI-561, a multi-planet system in galactic thick disk that contains rocky, ultra-short period planet (USP). This bright ($V=10.2$) star hosts three small transiting planets identified photometry from NASA TESS mission: TOI-561 b (TOI-561.02, P=0.44 days, $R_b = 1.45\pm0.11\,R_\oplus$), c (TOI-561.01, P=10.8 $R_c=2.90\pm0.13\,R_\oplus$), and d (TOI-561.03, P=16.3 $R_d=2.32\pm0.16\,R_\oplus$). The is chemically ([Fe/H]$=-0.41\pm0.05$, [$\alpha$/H]$=+0.23\pm0.05$)...
Abstract The extreme environments of ultra-short-period planets (USPs) make excellent laboratories to study how exoplanets obtain, lose, retain, and/or regain gaseous atmospheres. We present the confirmation and characterization USP TOI-1347 b, a 1.8 ± 0.1 R ⊕ planet on 0.85 day orbit that was detected with photometry from TESS mission. measured radial velocities system using Keck/HIRES HARPS-N found be unusually massive at 11.1 1.2 M . mass radius b imply an Earth-like bulk composition. A...
Abstract We conducted a search for technosignatures in 2018 and 2019 April with the L -band receiver (1.15–1.73 GHz) of 100 m diameter Green Bank Telescope. These observations focused on regions surrounding 31 Sun-like stars near plane Galaxy. present results our narrowband signals this data set, as well improvements to processing pipeline. Specifically, we applied an improved candidate signal detection procedure that relies topographic prominence power, which nearly doubles count some...
Abstract We present the Distant Giants Survey, a three-year radial velocity campaign to measure P(DG∣CS), conditional occurrence of distant giant planets (DG; M p ∼ 0.3–13 J , P > 1 yr) in systems hosting close-in small planet (CS; R < 10 ⊕ ). For past two years, we have monitored 47 Sun-like stars transiting detected by TESS. selection criteria used assemble our sample and report discovery planets, TOI-1669 b TOI-1694 c. find that <?CDATA $M\sin i=0.573\pm 0.074\,\,{M}_{{\rm{J}}}$?>...
Abstract We present the discovery of a Jupiter-like planet, HD 73344 d ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>m</mml:mi> <mml:mi>d</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>2.5</mml:mn> <mml:msubsup> <mml:mn>5</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.46</mml:mn> </mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.56</mml:mn> </mml:msubsup> <mml:mspace width="1em"/> <mml:mi>M</mml:mi> <mml:mi>J</mml:mi> </mml:math> ,...
Abstract We present and confirm TOI-1751 b, a transiting sub-Neptune orbiting slightly evolved, solar-type, metal-poor star ( T eff = 5996 ± 110 K, <?CDATA $\mathrm{log}(g)=4.2\pm 0.1$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>g</mml:mi> stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mn>4.2</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.1</mml:mn> </mml:math> , V 9.3 mag, [Fe/H] −0.40 0.06 dex)...
Abstract Hot Neptunes, gaseous planets smaller than Saturn (∼3–8 R ⊕ ) with orbital periods less 10 days, are rare. Models predict this is due to high-energy stellar irradiation stripping planetary atmospheres over time, often leaving behind only rocky cores. Using our TESS full-frame-image pipeline giants in conjunction Keck/HIRES radial velocity measurements, we present the discovery of TIC365102760 b, a 6.2 (0.55 J ), 19.2 M (0.060 planet transiting red giant star every 4.21285 days. The...
Abstract Highly eccentric orbits are one of the major surprises exoplanets relative to solar system and indicate rich tumultuous dynamical histories. One particular interest is Kepler-1656, which hosts a sub-Jovian planet with an eccentricity 0.8. Sufficiently will shrink in semimajor axis due tidal dissipation orbital energy during periastron passage. Here our goal was assess whether Kepler-1656b currently undergoing such high-eccentricity migration, further understand system’s origins...
Abstract With JWST’s successful deployment and unexpectedly high fuel reserves, measuring the masses of sub-Neptunes transiting bright, nearby stars will soon become bottleneck for characterizing atmospheres small exoplanets via transmission spectroscopy. Using a carefully curated target list observations from more than 2 yr APF-Levy Keck-HIRES Doppler monitoring, TESS-Keck Survey is working toward alleviating this pressure. Here we present mass measurements 11 planets in eight systems that...
Abstract We present the stellar and planetary properties for 85 TESS Objects of Interest (TOIs) hosting 108 planet candidates that compose TESS-Keck Survey (TKS) sample. combine photometry, high-resolution spectroscopy, Gaia parallaxes to measure precise accurate properties. then use these parameters as inputs a light-curve processing pipeline recover signals homogeneously fit their transit Among fits, we detect significant transit-timing variations among at least three multiplanet systems...
Abstract We confirm a massive sub-Neptune-sized planet on P = 22.8 days orbit around the star TOI-1824 ( T eff 5200 K, V 9.7 mag). TESS first identified b (formerly TOI-1824.01) as an object of interest in 2020 April after two transits Sector 22 were matched with single transit 21. was subsequently targeted for ground-based Doppler monitoring Keck-HIRES and APF-Levy. Using joint model photometry, radial velocities, Ca ii H K emission measurements activity indicator, we find that is unusually...
Abstract We present optical spectroscopy of 710 solar neighborhood stars collected over 20 years to catalog chromospheric activity and search for stellar cycles. The California Legacy Survey are amenable exoplanet detection using precise radial velocities, we their Ca ii H K time series as a proxy activity. Using the High Resolution Echelle Spectrometer at Keck Observatory, measured flux in cores lines determine S -values on Mount Wilson scale <mml:math...
Multi-planet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf ($\rm{V=11.6,~K=9.9}$) four transiting sub-Neptunes identified by TESS orbital periods of $4.31~\rm{d},~5.90~\rm{d},~18.66~\rm{d}$, $~37.92~\rm{d}$. We collected 130 radial velocity observations Keck/HIRES TNG/HARPS-N to measure planet masses. refit the 14 sectors photometry refine radii ($\rm{2.97 \pm...
Abstract Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those the most eccentric are valuable laboratories for testing theories high-eccentricity migration. However, few such transit their host stars, thus removing ability to apply constraints formation from bulk internal compositions. We report discovery Kepler-1704 b, transiting 4.15 M J planet 988.88 day orbit an extreme eccentricity <?CDATA...
We report the discovery of HIP-97166b (TOI-1255b), a transiting sub-Neptune on 10.3-day orbit around K0 dwarf 68 pc from Earth. This planet was identified in systematic search TESS Objects Interest for planets with eccentric orbits, based mismatch between observed transit duration and expected circular orbit. confirmed planetary nature ground-based radial velocity measurements measured mass $M_{b} =$ 20 $\pm$ 2 $M_\bigoplus$ along radius $R_{b} 2.7 0.1 $R_\bigoplus$ photometry. detected an...