About

Gregory Laughlin is a Professor of Astronomy and the Director of Undergraduate Studies at Yale University. He is affiliated with the Yale Center for Astronomy and Astrophysics. His professional role involves leading undergraduate education and contributing to the university's astronomy research community. His office is located at Kline Tower 619.

Research topics

• Astrophysics
• Physics
• Astronomy
• Quantum mechanics
• Particle physics
• Geology
• Statistical physics
• Astrobiology
• Geodesy
• Classical mechanics

Selected publications

• A Larger Sample Confirms Small Planets Around Hot Stars Are Misaligned

  arXiv (Cornell University) · 2024-05-30

  preprintOpen accessSenior author

  The distribution of stellar obliquities provides critical insight into the formation and evolution pathways of exoplanets. In the past decade, it was found that hot stars hosting hot Jupiters are more likely to have high obliquities than cool stars, but it is not clear whether this trend exists only for hot Jupiters or holds for other types of planets. In this work, we extend the study of the obliquities of hot (6250-7000\,K) stars with transiting super-Earth and sub-Neptune-sized planets. We constrain the obliquity distribution based on measurements of the stars' projected rotation velocities. Our sample consists of 170 TESS and \textit{Kepler} planet-hosting stars and 180 control stars chosen to have indistinguishable spectroscopic characteristics. In our analysis, we find evidence suggesting that the planet hosts have a systematically higher $\langle \sin i \rangle$ compared to the control sample. This result implies that the planet hosts tend to have lower obliquities. However, the observed difference in $\langle \sin i \rangle$ is not significant enough to confirm spin-orbit alignment, as it is 3.8$σ$ away from perfect alignment. We also find evidence that within the planet-hosting stars there is a trend of higher obliquity (lower $\langle \sin i\rangle$) for the hotter stars ($\teff > 6250$ K) than for the cooler stars in the sample. This suggests that hot stars hosting smaller planets exhibit a broader obliquity distribution($\langle \sin i\rangle = 0.79 \pm 0.053$) than cooler planet-hosting stars, indicating that high obliquities are not exclusive to hot Jupiters and instead are more broadly tied to hot stars.

  PublisherOA PDFDOI

• A Larger Sample Confirms Small Planets around Hot Stars Are Misaligned ^∗

  The Astrophysical Journal Letters · 2024-06-01 · 10 citations

  articleOpen accessSenior author

  Abstract The distribution of stellar obliquities provides critical insight into the formation and evolution pathways of exoplanets. In the past decade, it was found that hot stars hosting hot Jupiters are more likely to have high obliquities than cool stars, but it is not clear whether this trend exists only for hot Jupiters or holds for other types of planets. In this work, we extend the study of the obliquities of hot (6250–7000 K) stars with transiting super-Earth-sized and sub-Neptune-sized planets. We constrain the obliquity distribution based on measurements of the stars’ projected rotation velocities. Our sample consists of 170 TESS and Kepler planet-hosting stars and 180 control stars chosen to have indistinguishable spectroscopic characteristics. In our analysis, we find evidence suggesting that the planet hosts have a systematically higher <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> <mml:mo stretchy="false">〉</mml:mo> </mml:math> compared to the control sample. This result implies that the planet hosts tend to have lower obliquities. However, the observed difference in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> <mml:mo stretchy="false">〉</mml:mo> </mml:math> is not significant enough to confirm spin–orbit alignment as it is 3.8 σ away from perfect alignment. We also find evidence that within the planet-hosting stars there is a trend of higher obliquity (lower <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> <mml:mo stretchy="false">〉</mml:mo> </mml:math> ) for the hotter stars ( T eff &gt; 6250 K) than for the cooler stars in the sample. This suggests that hot stars hosting smaller planets exhibit a broader obliquity distribution ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> <mml:mo stretchy="false">〉</mml:mo> <mml:mo>=</mml:mo> <mml:mn>0.79</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.053</mml:mn> </mml:math> ) than cooler planet-hosting stars, indicating that high obliquities are not exclusive to hot Jupiters and instead are more broadly tied to hot stars.

  PublisherOA PDFDOI

• Sustaining the Moore's Law Analog for Exoplanets

  2024-01-01

  articleSenior author
  PublisherDOI

• Tidal Dissipation Regimes among the Short-period Exoplanets

  The Astrophysical Journal Letters · 2023-11-23 · 8 citations

  articleOpen access

  Abstract The efficiency of tidal dissipation provides a zeroth-order link to a planet’s physical properties. For super-Earth and sub-Neptune planets in the range R ⊕ ≲ R p ≲ 4 R ⊕ , particularly efficient dissipation (i.e., low tidal quality factors) may signify terrestrial-like planets capable of maintaining rigid crustal features. Here, we explore global constraints on planetary tidal quality factors using a population of planets in multiple-planet systems whose orbital and physical properties indicate susceptibility to capture into secular spin–orbit resonances. Planets participating in secular spin–orbit resonance can maintain large axial tilts and significantly enhanced heating from obliquity tides. When obliquity tides are sufficiently strong, planets in low-order mean-motion resonances can experience resonant repulsion (period ratio increase). The observed distribution of period ratios among transiting planet pairs may thus depend nontrivially on the underlying planetary structures. We model the action of resonant repulsion and demonstrate that the observed distribution of period ratios near the 2:1 and 3:2 commensurabilities implies Q values spanning from Q ≈ 10 1 –10 7 and peaking at Q ≈ 10 6 . This range includes the expected range in which super-Earth and sub-Neptune planets dissipate ( Q ≈ 10 3 –10 4 ). This work serves as a proof of concept for a method of assessing the presence of two dissipation regimes, and we estimate the number of additional multitransiting planetary systems needed to place any bimodality in the distribution on a strong statistical footing.

  PublisherOA PDFDOI

• Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions*  

  The Astronomical Journal · 2023-03-27 · 32 citations

  articleOpen access

  Abstract Directly imaging temperate rocky planets orbiting nearby, Sun-like stars with a 6 m class IR/O/UV space telescope, recently dubbed the Habitable Worlds Observatory, is a high-priority goal of the Astro2020 Decadal Survey. To prepare for future direct imaging (DI) surveys, the list of potential targets should be thoroughly vetted to maximize efficiency and scientific yield. We present an analysis of archival radial velocity data for southern stars from the NASA/NSF Extreme Precision Radial Velocity (EPRV) Working Group’s list of high-priority target stars for future DI missions (drawn from the HabEx, LUVOIR, and Starshade Rendezvous studies). For each star, we constrain the region of companion mass and period parameter space we are already sensitive to based on the observational baseline, sampling, and precision of the archival radial velocity (RV) data. Additionally, for some of the targets, we report new estimates of magnetic activity cycle periods, rotation periods, improved orbital parameters for previously known exoplanets, and new candidate planet signals that require further vetting or observations to confirm. Our results show that for many of these stars we are not yet sensitive to even Saturn-mass planets in the habitable zone, let alone smaller planets, highlighting the need for future EPRV vetting efforts before the launch of a DI mission. We present evidence that the candidate temperate super-Earth exoplanet HD 85512b is most likely due to the star’s rotation, and report an RV acceleration for δ Pav that supports the existence of a distant giant planet previously inferred from astrometry.

  PublisherOA PDFDOI

• Self-consistent Spin, Tidal, and Dynamical Equations of Motion in the REBOUNDx Framework

  The Astrophysical Journal · 2023 · 31 citations

  Senior authorCorresponding
  • Physics
  • Classical mechanics
  • Statistical physics

  Abstract We introduce self-consistent spin, tidal, and dynamical equations of motion into REBOUNDx , a library of additional effects for the popular N -body integrator REBOUND . The equations of motion used are derived from the constant time lag approximation to the equilibrium tide model of tidal friction. These effects will allow the study of a variety of systems of which the full dynamical picture cannot be encapsulated by point particle dynamics. We provide several test cases and benchmark the code’s performance against analytic predictions. The open-source code is available in the most recent release of REBOUNDx .

  PublisherOA PDFDOI

• Interstellar Comets from Post-Main Sequence Systems as Tracers of Extrasolar Oort Clouds

  arXiv (Cornell University) · 2023-06-21 · 1 citations

  preprintOpen accessSenior author

  Interstellar small bodies are unique probes into the histories of exoplanetary systems. One hypothesized class of interlopers are "Jurads," exo-comets released into the Milky Way during the post-main sequence as the thermally-pulsing asymptotic giant branch (AGB) host stars lose mass. In this study, we assess the prospects for the Legacy Survey of Space and Time (LSST) to detect a Jurad and examine whether such an interloper would be observationally distinguishable from exo-comets ejected during the (pre-)main sequence. Using analytic and numerical methods, we estimate the fraction of exo-Oort Cloud objects that are released from 1-8 solar mass stars during post-main sequence evolution. We quantify the extent to which small bodies are altered by the increased luminosity and stellar outflows during the AGB, finding that some Jurads may lack hypervolatiles and that stellar winds could deposit dust that covers the entire exo-comet surface. Next, we construct models of the interstellar small body reservoir for various size-frequency distribution slopes, characteristic sizes, and the total mass sequestered in the minor planets of exo-Oort Clouds. Even with the LSST's increased search volume compared to contemporary surveys, we find that detecting a Jurad is unlikely but not infeasible given the current understanding of (exo)planet formation.

  PublisherOA PDFDOI

• Constraints to Efficiently Find Interstellar Object Generated Craters on the Moon

  Research Notes of the AAS · 2023-10-27 · 1 citations

  articleOpen accessSenior author

  Abstract Recent observations of interstellar objects (ISO) crossing the solar system suggest the possible existence of ISO-generated craters on the Moon. We explore how different crater properties such as age, size, melt, and position can be used to search for ISO-generated craters on the lunar surface. We find that selecting young, small craters with a high volume of melt located away from the lunar poles increases the likelihood of association with a high-speed ISO by 100 fold as compared to selecting randomly, assuming high-speed ISO impacts generate melt. We note that craters from other sources however still massively outnumber ISO-generated craters.

  PublisherDOI

• Tidal Dissipation Regimes Among the Short-Period Exoplanets

  arXiv (Cornell University) · 2023-11-06

  preprintOpen access

  The efficiency of tidal dissipation provides a zeroth-order link to a planet's physical properties. For super-Earth and sub-Neptune planets in the range $R_{\oplus}\lesssim R_p \lesssim 4 R_{\oplus}$, particularly efficient dissipation (i.e., low tidal quality factors) may signify terrestrial-like planets capable of maintaining rigid crustal features. Here we explore global constraints on planetary tidal quality factors using a population of planets in multiple-planet systems whose orbital and physical properties indicate susceptibility to capture into secular spin-orbit resonances. Planets participating in secular spin-orbit resonance can maintain large axial tilts and significantly enhanced heating from obliquity tides. When obliquity tides are sufficiently strong, planets in low-order mean-motion resonances can experience resonant repulsion (period ratio increase). The observed distribution of period ratios among transiting planet pairs may thus depend non-trivially on the underlying planetary structures. We model the action of resonant repulsion and demonstrate that the observed distribution of period ratios near the 2:1 and 3:2 commensurabilties implies $Q$ values spanning from $Q\approx 10^1-10^7$ and peaking at $Q \approx 10^6$. This range includes the expected range in which super-Earth and sub-Neptune planets dissipate ($Q \approx 10^3 - 10^4$). This work serves as a proof of concept for a method of assessing the presence of two dissipation regimes, and we estimate the number of additional multi-transiting planetary systems needed to place any bimodality in the distribution on a strong statistical footing.

  PublisherOA PDFDOI

• Interstellar Comets from Post-main-sequence Systems as Tracers of Extrasolar Oort Clouds

  The Planetary Science Journal · 2023-07-01 · 11 citations

  articleOpen accessSenior author

  Abstract Interstellar small bodies are unique probes into the histories of exoplanetary systems. One hypothesized class of interlopers are “Jurads,” exocomets released into the Milky Way during the post-main-sequence as the thermally pulsing asymptotic giant branch (AGB) host stars lose mass. In this study, we assess the prospects for the Legacy Survey of Space and Time (LSST) to detect a Jurad and examine whether such an interloper would be observationally distinguishable from exocomets ejected during the (pre-)main-sequence. Using analytic and numerical methods, we estimate the fraction of exo–Oort Cloud objects that are released from 1–8 M ⊙ stars during post-main-sequence evolution. We quantify the extent to which small bodies are altered by the increased luminosity and stellar outflows during the AGB, finding that some Jurads may lack hypervolatiles and that stellar winds could deposit dust that covers the entire exocomet surface. Next, we construct models of the interstellar small body reservoir for various size–frequency distributions and examine the LSST’s ability to detect members of those hypothesized populations. Combining these analyses, we highlight the joint constraints that the LSST will place on power-law size–frequency distribution slopes, characteristic sizes, and the total mass sequestered in the minor planets of exo–Oort Clouds. Even with the LSST’s increased search volume compared to contemporary surveys, we find that detecting a Jurad is unlikely but not infeasible given the current understanding of (exo)planet formation.

  PublisherOA PDFDOI

Recent grants

• NeTS: Medium: Collaborative Research: The Internet at the Speed of Light

  NSF · $150k · 2018–2021

• CAREER: The Detection and Characterization of Extrasolar Planets

  NSF · $518k · 2005–2011

Frequent coauthors

• Drake Deming

  52 shared

• R. Paul Butler

  Carnegie Institution for Science

  45 shared

• Debra A. Fischer

  40 shared

• Fred C. Adams

  36 shared

• Jonathan Langton

  Sunshine Coast University Hospital

  30 shared

• Steven S. Vogt

  30 shared

• Andrew W. Howard

  California Institute of Technology

  28 shared

• David Charbonneau

  28 shared