A5074105800- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Laser-induced spectroscopy and plasma
- Space Exploration and Technology
- SAS software applications and methods
- Molecular Spectroscopy and Structure
- Adaptive optics and wavefront sensing
- Isotope Analysis in Ecology
- Atmospheric Ozone and Climate
- Galaxies: Formation, Evolution, Phenomena
- Animal Ecology and Behavior Studies
- Pulsars and Gravitational Waves Research
- Non-Destructive Testing Techniques
- Computational Physics and Python Applications
- Laser-Plasma Interactions and Diagnostics
- Surface Roughness and Optical Measurements
- Radio Astronomy Observations and Technology
- Spectroscopy and Laser Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Tribology and Lubrication Engineering
Amherst College
2021-2024
Alfred University
2024
Boston University
2017-2022
University of Montana
2015
U.S. National Science Foundation
1999
Sandia National Laboratories California
1990
Abstract Snowlines of major volatiles regulate the gas and solid C/N/O ratios in planet-forming midplanes protoplanetary disks. Snow surfaces are 2D extensions snowlines outer disk regions, where radiative heating results an increasing temperature with height. CO N 2 two most abundant carriers C, N, O. H + can be used to probe snow both molecules, because it is destroyed by formed from . Here we present Atacama Large Millimeter/submillimeter Array (ALMA) observations at ∼0.″2–0.″4 resolution...
Abstract Accretion signatures from bound brown dwarf and protoplanetary companions provide evidence for ongoing planet formation, accreting substellar objects have enabled new avenues to study the astrophysical mechanisms controlling formation accretion processes. Delorme 1 (AB)b, a ∼30–45 Myr circumbinary planetary-mass companion, was recently discovered exhibit strong H α emission. This suggests circumplanetary disk, somewhat surprising given canonical gas disk dispersal timescales of 5–10...
Abstract The Hubble UV Legacy Library of Young Stars as Essential Standards (ULLYSES) Director’s Discretionary Program low-mass pre-main-sequence stars, coupled with forthcoming data from Atacama Large Millimeter/submillimeter Array and James Webb Space Telescope, will provide the foundation to revolutionize our understanding relationship between young stars their protoplanetary disks. A comprehensive evaluation physics disk evolution planet formation requires intricate relationships mass...
Abstract Accretion plays a central role in the physics that governs evolution and dispersal of protoplanetary disks. The primary goal this paper is to analyze stability over time mass accretion rate onto TW Hya, nearest accreting solar-mass young star. We measure veiling across optical spectrum 1169 archival high-resolution spectra obtained from 1998–2022. then converted using 26 flux-calibrated cover Balmer jump. measured excess continuum has an average 2.51 × 10 −9 M ⊙ yr −1 Gaussian...
The Miniature Exoplanet Radial Velocity Array (MINERVA) is a U.S.-based observational facility dedicated to the discovery and characterization of exoplanets around nearby sample bright stars. MINERVA employs robotic array four 0.7-m telescopes outfitted for both high-resolution spectroscopy photometry, designed completely autonomous operation. primary science program radial velocity survey secondary objective obtain high-precision transit light curves. modular design flexibility our hardware...
We report the discovery of eclipses by circumstellar disc material associated with young star PDS 110 in Ori OB1a association using SuperWASP and KELT surveys. (HD 290380, IRAS 05209-0107) is a rare Fe/Ge-type star, ~10 Myr-old accreting intermediate-mass showing strong infrared excess (L$_{\rm IR}$/L$_{\rm bol}$ ~ 0.25). Two extremely similar depth ~30\% duration ~25 days were observed November 2008 January 2011. interpret as caused same structure an orbital period $808\pm2$ days. Shearing...
Variability is a defining characteristic of young low-mass stars that are still accreting material from their primordial protoplanetary disk. Here we present the largest \textit{HST} variability study Classical T Tauri (CTTS) to date. For 5 these objects, obtained total 25 spectra with Space Telescope Imaging Spectrograph (STIS). Mass accretion rates and fraction star covered by columns (i.e., filling factors) were inferred using 1D NLTE physical models whose parameters fit within Bayesian...
Abstract Magnetospheric accretion models predict that matter from protoplanetary disks accretes onto stars via funnel flows, which follow stellar magnetic field lines and shock on the surfaces 1–3 , leaving hot spots with density gradients 4–6 . Previous work has provided observational evidence of varying in 7 but these observations were not sensitive to radial distribution. Attempts have been made measure this distribution using X-ray 8–10 ; however, emission traces only a fraction spot...
Abstract The coevolution of T Tauri stars and their surrounding protoplanetary disks dictates the timescales planet formation. In this paper, we present magnetospheric accretion inner disk wall model fits to near-UV (NUV) near-IR (NIR) spectra nine classical in Orion OB1b as part Outflows Disks around Young Stars: Synergies for Exploration ULLYSES Spectra (ODYSSEUS) survey. Using NUV–optical from Hubble UV Legacy Library Stars Essential Standards (ULLYSES) Director’s Discretionary Program...
Abstract Accretion rates ( <?CDATA $\dot{M}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> </mml:math> ) of young stars show a strong correlation with object mass M ); however, extension the $\dot{M}\mbox{--}M$?> <mml:mo>–</mml:mo> relation into substellar regime is less certain. Here, we present Comprehensive Archive Substellar and Planetary Rates (CASPAR),...
Abstract The classical T Tauri star (CTTS) stage is a critical phase of the and planet formation process. In an effort to better understand mass accretion processes, which can dictate future stellar evolution formation, multiepoch, multiwavelength photometric spectroscopic monitoring campaign four CTTSs (TW Hya, RU Lup, BP Tau, GM Aur) was carried out in 2021 2022/2023 as part Outflows Disks around Young Stars: Synergies for Exploration ULLYSES Spectra program. Here we focus on Hubble Space...
Abstract Classical T Tauri stars (CTTSs) are young, low-mass that accrete material from their surrounding protoplanetary disk. To better understand accretion variability, we conducted a multiepoch, multiwavelength photometric monitoring campaign of four CTTSs, TW Hya, RU Lup, BP Tau, and GM Aur, in 2021 2022, contemporaneous with Hubble Space Telescope UV optical spectra. We find all targets display significant variability light curves, generally on days-long timescales (but some cases...
Abstract Our understanding of protoplanetary disks is rapidly departing from the classical view a smooth, axisymmetric disk. This in part thanks to high angular resolution that (sub)millimeter observations can provide. Here, we present combined results Atacama Large Millimeter/submillimeter Array (ALMA) (0.9 mm) and Very (VLA) (7 dust continuum toward disk around solar analog GM Aur. Both images clearly resolve ∼35 au inner cavity. The ALMA also reveal fainter extends up ∼250 au. We model...
Interpreting the short-timescale variability of accreting, young, low-mass stars known as Classical T Tauri remains an open task. Month-long, continuous light curves from Transiting Exoplanet Survey Satellite (\textit{TESS}) have become available for hundreds stars. With this vast data set, identifying connections between observed by \TESS and accretion is valuable characterizing process. To end, we obtained short-cadence observations 14 in Taurus star-formation region along with...
Abstract Photometric observations of accreting, low-mass, pre-main-sequence stars (i.e., Classical T Tauri stars; CTTS) have revealed different categories variability. Several these classifications been linked to changes in <?CDATA $\dot{M}$?> . To test how accretion variability conditions lead light-curve morphologies, we used 1D hydrodynamic simulations along a magnetic field line coupled with radiative transfer models and simple treatment rotation generate synthetic light curves. We...
Absorption features in stellar atmospheres are often used to calibrate photocentric velocities for kinematic analysis of further spectral lines. The Li feature at $\sim$ 6708 {\AA} is commonly used, especially the case young objects which it one strongest absorption However, this a complex line comprising two isotope fine-structure doublets. We empirically measure wavelength sample stars from PENELLOPE/VLT programme (using X-Shooter, UVES and ESPRESSO data) as well HARPS data. For 51...
The high-energy radiation fields of T Tauri stars (TTS) should affect the surrounding circumstellar disk, having implications for disk transport and heating. Yet, observational evidence effect on disks is scarce. Here we investigate connection between X-ray emission innermost gas by leveraging variability TTS. We obtained multiple epochs coordinated data (taken either simultaneously or within a few hours) accreting TTS with Hubble Space Telescope, Neil Gehrels Swift Observatory, Chandra...
Abstract Herbig Ae/Be (HAeBe) stars have been classified into Group I or II, and were initially thought to be flared flat disks, respectively. Several sources shown large gaps, suggesting ongoing planet formation, while no gaps found in the disks of II sources. We analyzed disk around source, HD 142666, using irradiated accretion modeling broadband spectral energy distribution along with 1.3 mm spatial brightness traced by Atacama Large Millimeter Submillimeter Array (ALMA) observations. Our...
We analyze Herschel Space Observatory observations of 104 young stellar objects with protoplanetary disks in the ~1.5 Myr star-forming region Lynds 1641 (L1641) within Orion A Molecular Cloud. present spectral energy distributions from optical to far-infrared including new photometry Photodetector Array Camera and Spectrometer (PACS) at 70 microns. Our sample, taken as part Protostar Survey, contains 24 transitional disks, eight which we identify for first time this work. full irradiated...
The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7 m robotic telescopes fiber-fed to KiwiSpec spectrograph. MINERVA mission discover super-Earths in the habitable zones nearby stars. This can be accomplished with MINERVA's unique combination high precision and cadence over long time periods. In this work, we detail changes facility that have occurred since our previous paper. We then describe control software, process by which perform 1D spectral...
We present a detailed study of the disk around intermediate-mass star SO 411, aiming to explain spectral energy distribution this star. show that is transitional truncated at ∼11 au, with ∼0.03 lunar masses optically thin dust inside cavity. Gas also flows through cavity, since we find still accreting mass onto star, rate ∼5 × 10−9 M☉ yr−1. Until now, 411 has been thought belong ∼3 Myr old σ Orionis cluster. However, analyzed second Gaia Data Release in combination kinematic data previously...