A5009049731- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Distributed and Parallel Computing Systems
- Astronomy and Astrophysical Research
- High-Energy Particle Collisions Research
- Astronomical Observations and Instrumentation
- Scientific Computing and Data Management
- Dark Matter and Cosmic Phenomena
- Advanced Data Storage Technologies
- History and Developments in Astronomy
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Neutrino Physics Research
- Particle Accelerators and Free-Electron Lasers
- Geomagnetism and Paleomagnetism Studies
- Quantum Chromodynamics and Particle Interactions
- Particle accelerators and beam dynamics
- Radiation Detection and Scintillator Technologies
- Planetary Science and Exploration
- Computational Physics and Python Applications
- Solar Radiation and Photovoltaics
- Geophysics and Gravity Measurements
Johnson Space Center
2022-2024
National Aeronautics and Space Administration
2024
Analysis Group (United States)
2024
High Altitude Observatory
2015-2023
NSF National Center for Atmospheric Research
2015-2023
Montana State University
2015-2017
University of Minnesota
2003-2012
Austrian Academy of Sciences
2012
Twin Cities Orthopedics
2009-2012
Institute of High Energy Physics
2012
Precise photometry from the Kepler space telescope allows not only measurement of rotation in solar-type field stars, but also determination reliable masses and ages asteroseismology. These critical data have recently provided first opportunity to calibrate rotation-age relations for stars older than Sun. The evolutionary picture that emerges is surprising: beyond middle-age efficiency magnetic braking dramatically reduced, implying a fundamental change angular momentum loss Rossby number...
The most commonly used index of stellar magnetic activity is the instrumental flux scale singly-ionized calcium H & K line core emission, S, developed by Mount Wilson Observatory (MWO) HK Project, or derivative R'_HK. Accurately placing Sun on S important for comparing solar to that Sun-like stars. We present previously unpublished measurements reflected sunlight from Moon using second-generation MWO photometer during cycle 23 and determine minimum S_min,23 = 0.1634 +/- 0.0008, amplitude...
Abstract The Sun exhibits a well-observed modulation in the number of spots on its disk over period about 11 years. From dawn modern observational astronomy, sunspots have presented challenge to understanding—their quasi-periodic variation number, first noted 175 years ago, has stimulated community-wide interest this day. A large techniques are able explain temporal landmarks, (geometric) shape, and amplitude sunspot “cycles,” however, forecasting these features accurately advance remains...
Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they the product of broad set physical processes corona out through extent heliosphere, and provide insight into particle acceleration transport that widely applicable in astrophysics. From operations perspective, SEP pose radiation hazard for aviation, electronics space, human space exploration, particular missions outside Earth's protective magnetosphere including to Moon Mars. Thus, it is critical...
Observations of Sun-like stars over the last half-century have improved our understanding how magnetic dynamos, like that responsible for 11-year solar cycle, change with rotation, mass and age. Here we show first time metallicity can affect a stellar dynamo. Using most complete set observations cycle ever obtained star, analog HD 173701 exhibits solar-like differential rotation 7.4-year activity cycle. While duration is comparable to generated by dynamo, amplitude brightness variability...
We previously identified an event in the solar timeline that appeared to play a role how sunspot Cycle 23 (SC23) transitioned into 24 (SC24). The timeframe for this transition was rapid, taking place over very short time and perhaps as single rotation. Further, we inferred observed critical moment Sun’s global-scale magnetic field it being manifest spatially temporally overlapping systems belonging 22-year (Hale) cycle. These events have been dubbed Hale terminations, or ‘terminators’ short....
Space radiation is a notable hazard for long-duration human spaceflight
We identify a set of 18 solar analogs among the seismic sample solar-like stars observed by Kepler satellite rotating between 10 and 40 days. This is constructed using asteroseismic stellar properties derived either global oscillation or individual acoustic frequencies. measure magnetic activity these observations collected photometric ground-based, high-resolution Hermes spectrograph mounted on Mercator telescope. The photospheric (Sph) chromospheric (S index) levels are estimated compared...
Nearly half a century has passed since the initial indications that stellar rotation slows while chromospheric activity weakens with power-law dependence on age, so-called Skumanich relations. Subsequent characterization of mass-dependence this behavior up to age Sun led advent gyrochronology, which uses rate star infer its from an empirical calibration. The efficacy method relies predictable angular momentum loss wind entrained in large-scale magnetic field produced by global dynamo action....
A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also other stars. Many solar activity proxies exhibit a quasi-biennial (∼2 year) variation, which is superimposed upon dominant 11 year cycle. well-characterized stellar sample at least two relationships between rotation period and cycle period, with some stars exhibiting long short cycles simultaneously. Within this sample, periods are typical...
The continuous photometric observations collected by the Kepler satellite over 4 years provide a whelm of data with an unequalled quantity and quality for study stellar evolution more than 200000 stars. Moreover, length dataset unique source information to detect magnetic activity associated temporal variability in acoustic oscillations. In this regards, mission was awaited great expectation. search signature solar-like pulsations still remained unfruitful 2 after end nominal mission. Here,...
The photometric time series of solar-like stars can exhibit rotational modulation due to active regions co-rotating with the stellar surface, allowing us constrain rotation and magnetic activity. In this work we investigate behavior, particularly variability, activity Kepler compare it that Sun. We adopted proxy Sph, which was computed a cadence 5 x period, Prot. average Sph taken as mean level, standard deviation measure temporal variation over observations. also analyzed Sun-as-a-star data...
Abstract The bright star λ Ser hosts a hot Neptune with minimum mass of 13.6 M ⊕ and 15.5 day orbit. It also appears to be solar analog, mean rotation period 25.8 days surface differential very similar the Sun. We aim characterize fundamental properties this system constrain evolutionary pathway that led its present configuration. detect solar-like oscillations in time series photometry from Transiting Exoplanet Survey Satellite, we derive precise asteroseismic detailed modeling. obtain new...
Abstract Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age mass have relied observations of clusters, where isochrones from evolution models are used determine the properties ensemble. Asteroseismology employs similar measure an individual star by matching its normal modes oscillation, yielding with high precision. We use 27 days photometry Transiting Exoplanet Survey Satellite characterize solar-like oscillations in G8 subgiant 94 Aqr triple system....
Abstract We take a broad look at the problem of identifying magnetic solar causes space weather. With lackluster performance extrapolations based upon field measurements in photosphere, we identify region near-UV (NUV) part spectrum as optimal for studying development free energy over active regions. Using data from SORCE, Hubble Space Telescope, and SKYLAB, along with 1D computations NUV numerical experiments on MURaM radiation–magnetohydrodynamic HanleRT radiative transfer codes, address...
The PhEDEx Data Service provides access to information from the central database, as well certificate-authenticated managerial operations such requesting transfer or deletion of data. is integrated with "SiteDB" service for fine-grained control, providing a safe and secure environment operations. A plug-in architecture allows server-side modules be developed rapidly easily by anyone familiar schema, can automatically return data in variety formats use different client technologies. Using...
Context. Lithium abundance A(Li) and surface rotation are good diagnostic tools to probe the internal mixing angular momentum transfer in stars.
We investigate the occurrence of "extended solar cycle" (ESC) as it occurs in a host observational data spanning 140 years. Investigating coronal, chromospheric, photospheric and interior diagnostics we develop consistent picture activity migration linked to 22-year Hale (magnetic) cycle using superposed epoch analysis (SEA) previously identified termination events key time for SEA. Our shows that ESC cycle, highlighted by terminator-keyed SEA, is strongly recurrent throughout entire record...
The CMS experiment will need to sustain uninterrupted high reliability, throughput and very diverse data transfer activities as the LHC operations start. PhEDEx, system, be responsible for full range of needs experiment. Covering entire spectrum is a demanding task: from critical high-throughput transfers between CERN Tier-1 centres, high-scale production among Tier-2 managing 24/7 all 170 institutions in providing straightforward access handful files individual physicists.