C. P. Stevens
A5076576999- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Air Traffic Management and Optimization
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- SAS software applications and methods
Virginia Tech
2023-2024
Westminster College - Pennsylvania
2019-2020
Abstract We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee at D = 32 ± 3 Mpc, finding excess flux in first days after explosion, particularly our 10 minutes cadence TESS light curve and Swift UV data. Compared to a few other normal SNe with early flux, SN is redder less luminous. optical spectra 2023bee, including two during period where dominant. At this time, are similar those but weaker Si ii , C ii, Ca absorption lines,...
Abstract We present a JWST/MIRI low-resolution mid-infrared (MIR) spectroscopic observation of the normal Type Ia supernova (SN Ia) SN 2021aefx at +323 days past rest-frame B -band maximum light. The spectrum ranges from 4 to 14 μ m and shows many unique qualities, including flat-topped [Ar iii ] 8.991 profile, strongly tilted [Co 11.888 feature, multiple stable Ni lines. These features provide critical information about physics explosion. observations are compared synthetic spectra detailed...
We report the discovery of a warm sub-Saturn, TOI-257b (HD 19916b), based on data from NASA's Transiting Exoplanet Survey Satellite (TESS). The transit signal was detected by TESS and confirmed to be planetary origin radial velocity observations. An analysis photometry, Minerva-Australis, FEROS, HARPS velocities, asteroseismic stellar oscillations reveals that has mass $M_P=0.138\pm0.023$\,$\rm{M_J}$ ($43.9\pm7.3$\,$M_{\rm \oplus}$), radius $R_P=0.639\pm0.013$\,$\rm{R_J}$...
Abstract We present a JWST mid-infrared (MIR) spectrum of the underluminous Type Ia Supernova (SN Ia) 2022xkq, obtained with medium-resolution spectrometer on Mid-Infrared Instrument (MIRI) ∼130 days post-explosion. identify first MIR lines beyond 14 μ m in SN observations. find features unique to SNe Ia, including following: isolated emission stable Ni, strong blends [Ti ii ], and large ratios singly ionized doubly species both [Ar] [Co]. Comparisons normal-luminosity spectra at similar...
ABSTRACT We report the All-Sky Automated Survey for SuperNovae discovery of tidal disruption event (TDE) ASASSN-23bd (AT 2023clx) in NGC 3799, a LINER galaxy with no evidence strong active galactic nucleus (AGN) activity over past decade. With redshift z = 0.01107 and peak ultraviolet (UV)/optical luminosity (5.4 ± 0.4) × 1042 erg s−1, is lowest-redshift least-luminous TDE discovered to date. Spectroscopically, shows H α He i emission throughout its spectral time series, there are coronal...
Abstract We present a JWST MIRI medium-resolution spectrometer spectrum (5–27 μ m) of the Type Ia supernova (SN Ia) SN 2021aefx at +415 days past B -band maximum. The spectrum, which was obtained during iron-dominated nebular phase, has been analyzed in combination with previous observations to provide first time series analysis an Ia. find that temporal evolution [Co iii ] 11.888 m feature directly traces decay 56 Co. spectra, line profiles, and their are off-center delayed-detonation...
Abstract We announce the discovery of KELT-23Ab, a hot Jupiter transiting relatively bright ( V = 10.3) star BD+66 911 (TYC 4187-996-1), and characterize system using follow-up photometry spectroscopy. A global fit to yields host-star properties <?CDATA ${T}_{\mathrm{eff}}\,=5900\pm 49$?> K, ${M}_{* }={0.945}_{-0.054}^{+0.060}\,{M}_{\odot }$?> , ${R}_{* }=0.995\pm 0.015\,{R}_{\odot ${L}_{* }={1.082}_{-0.048}^{+0.051}\,{L}_{\odot $\mathrm{log}{g}_{\star }={4.418}_{-0.025}^{+0.026}$?> (cgs),...
We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee in NGC~2708 ($D = 32 \pm 3$ Mpc), finding excess flux first days after explosion relative to expected power-law rise from an expanding fireball. This deviation typical behavior for SNe is particularly obvious our 10-minute cadence $TESS$ light curve and $Swift$ UV data. Compared a few other normal with detected early flux, SN redder less luminous. optical spectra 2023bee, including...
Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions formation mechanisms. To know the planet, we must host star in as much detail possible. We present complete results planet-candidate hosts from K2-HERMES survey, which uses HERMES multi-object spectrograph on Anglo-Australian Telescope to obtain R$\sim$28,000 spectra more than 30,000 K2 stars. host-star parameters radii 224 candidate planets C1-C13. Our cast severe doubt 30...
We report the All-Sky Automated Survey for SuperNovae discovery of tidal disruption event (TDE) ASASSN-23bd (AT 2023clx) in NGC 3799, a LINER galaxy with no evidence strong AGN activity over past decade. With redshift $z = 0.01107$ and peak UV/optical luminosity $(5.4\pm0.4)\times10^{42}$ erg s$^{-1}$, is lowest-redshift least-luminous TDE discovered to date. Spectroscopically, shows H$\alpha$ He I emission throughout its spectral time series, UV spectrum nitrogen lines without carbon...
We present a JWST mid-infrared spectrum of the under-luminous Type Ia Supernova (SN Ia) 2022xkq, obtained with medium-resolution spectrometer on Mid-Infrared Instrument (MIRI) $\sim130$ days post-explosion. identify first MIR lines beyond 14 $\mu$m in SN observations. find features unique to SNe Ia, including: isolated emission stable Ni, strong blends [Ti II], and large ratios singly ionized doubly species both [Ar] [Co]. Comparisons normal-luminosity spectra at similar phases show...