A5074282470- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Science Education and Pedagogy
- Evaluation of Teaching Practices
- Pulsars and Gravitational Waves Research
- Reflective Practices in Education
- Astronomy and Astrophysical Research
- Innovative Teaching Methods
- Collaborative Teaching and Inclusion
- Astro and Planetary Science
- History and Developments in Astronomy
- Relativity and Gravitational Theory
- Innovative Teaching and Learning Methods
- Astrophysics and Star Formation Studies
- Motivation and Self-Concept in Sports
- Education and Critical Thinking Development
- Health and Medical Research Impacts
- Global Health and Surgery
- Health and Medical Education
- Science Education and Perceptions
- History and Theory of Mathematics
- Knowledge Societies in the 21st Century
University of British Columbia
2015-2023
Kansas State University
2019-2020
Drexel University
2020
American Association of Physics Teachers
2020
Canadian Institute for Theoretical Astrophysics
2012-2015
University of Toronto
2015
University of California, Berkeley
2004-2012
University of California System
2009
Planetary Science Institute
2006
California Institute of Technology
2003-2004
While gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, vast majority MBHs are considered dormant. Occasionally, a star passing too near MBH is torn apart by gravitational forces, leading to bright panchromatic tidal disruption flare (TDF). high-energy transient Swift J164449.3+573451 ("Sw 1644+57") initially displayed none theoretically anticipated (nor previously observed) TDF characteristics, we show that observations (Levan...
We have analyzed the redshift-dependent fraction of galactic bars over 0.2
A star that wanders too close to a massive black hole (BH) is shredded by the BH's tidal gravity. Stellar gas falls back BH, releasing flare of energy. In anticipation upcoming transient surveys, we predict light curves and spectra flares as function time, highlighting unique signatures in optical near-IR. Some initially bound BH likely blown away when fallback rate super-Eddington at early times. This outflow produces an luminosity comparable supernova; such events have durations ~10 days...
AU Microscopii is a 12 Myr old M dwarf that harbors an optically thin, edge-on disk of dust. The scattered light surface brightness falls with projected distance b from the star as b-α; within = 43 AU, α ≈ 1-2, while outside 4-5. We devise theory to explain this profile. At stellocentric r rBR we posit ring parent bodies on circular orbits: ``birth ring,'' wherein micron-sized grains are born collisional attrition bodies. ``inner disk'' at < contains migrate inward by corpuscular and...
We present the discovery and characterisation of PTF10iya, a short-lived (dt ~ 10 d, with an optical decay rate 0.3 mag per d), luminous (M_g -21 mag) transient source found by Palomar Transient Factory. The ultraviolet/optical spectral energy distribution is reasonably well fit blackbody T 1-2 x 10^4 K peak bolometric luminosity L_BB 1-5 10^44 erg s (depending on details extinction correction). A comparable amount radiated in X-ray band that appears to result from distinct physical process....
During the tidal disruption of a main-sequence star by massive black hole (BH) having mass MBH≲ 107 M⊙, stellar debris is expected to fall back BH at rate well above Eddington rate. Some fraction this gas predicted be blown away from BH, producing an optically bright flare radiation. We predict spectra and spectral evolution events, focusing on signatures produced photoionized outside photosphere super-Eddington outflow. show that spectrum such outflow should absorption lines are strongly...
Previous optical studies found an unexpected deficit of bars at z > 0.7. To investigate the effects band shifting, we have studied fraction barred spiral galaxies in Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) Hubble Deep Field-North. At 0.7, find least four galaxies, doubling number previously detected. The is small because these (and previous) data lack adequate spatial resolution. A typical 5 kpc bar 0.7 only marginally detectable for Wide Field Planetary 2 (WFPC2) 0.8 μm;...
Using a 1D height integrated model, we calculate the evolution of an unequal mass binary black hole with coplanar gas disc that contains gap due to presence secondary hole. Viscous outer circumbinary initially hardens binary, while inner drains on primary (central) As long as remains cool and thin at low (rather than becoming hot geometrically thick), reaches asymptotic typically ∼10−3–10−4 M⊙. Once semimajor axis shrinks below critical value, angular momentum losses from gravitational waves...
ABSTRACT We present a Hubble Space Telescope Imaging Spectrograph spectrum of ASASSN-14li, the first rest-frame ultraviolet (UV) tidal disruption flare (TDF). The underlying continuum is well fit by blackbody with K, an order magnitude smaller than temperature inferred from X-ray spectra (and significantly more precise previous efforts based on optical and near-UV photometry). Superimposed this blue continuum, we detect three classes features: narrow absorption Milky Way (probably...
Was PS1-10jh, an optical/ultraviolet transient discovered by the Pan-STARRS Medium Deep Survey, tidal disruption of a star massive black hole (BH)? We address two aspects problem: composition putative disrupted object (using spectroscopic data), and energetics observed gas radiation photometric data). perform photoionization calculations compare with lower limit line ratio |$L_{\rm He\,\small {II}\,\, 4686}/L_{\rm H\alpha }>5$| to argue that this event was not solar-type star, instead likely...
Much work in physics education research (PER) characterizes faculty teaching practice terms of whether use specific named PER-based methods, either with fidelity or adaptation; we call this paradigm the "teaching-method-centered paradigm." However, most do not frame their which particular methods they use, but rather own ideas and values, suggesting that teaching-method-centered misses key features teaching. These include productive have about student learning agency around We present three...
PhysPort (www.physport.org) has become the go-to place for physics educators to learn apply research-based teaching and assessment in their classrooms. Usage (defined as total number of visits) doubled every two years since site was released 2011, 20% all U.S. faculty 7% high school teachers are now verified on PhysPort. The lead author conceived 2007 after meeting many instructors interested incorporating results education research (PER) classrooms but with no idea where start. At time,...
While both society and astronomy have evolved greatly over the past fifty years, academic institutions incentives that shape our field remained largely stagnant. As a result, astronomical community is faced with several major challenges, including: (1) training we provide does not align skills future astronomers will need, (2) postdoctoral phase becoming increasingly demanding demoralizing, (3) jobs are unfriendly to families children. Solving these problems require conscious engineering of...
A goal of many university physics courses is that students increase their appreciation as an evidence-based way understanding the world, and they begin to develop self-identity scientists.Discouragingly, studies have found attitudes about science are very difficult affect positively.In our "structured quantitative inquiry" first-year lab course (SQILab) at University British Columbia, we introduced weekly reflection activities specifically targeting students' beliefs nature...
PhysPort is a professional development website for physics faculty to develop their teaching through research-based resources.As part of PhysPort's ongoing research efforts, we conducted interviews with 23 from diverse instructional and institutional contexts in the US.From our interviews, sought common experiences, motivations, pain points personas-person-like constructs-of US.Our focuses on perspectives key users site, thus take user-centered perspective rather than researcher-centered...
Supporting faculty to develop their teaching is important for all universities—and especially and challenging in universities that are new, highly multicultural, and/or developing countries. The University of Central Asia typifies these challenges opportunities. We offer a case study motivation engage professional development program called Teaching Triangles (TTs) at this university. In TTs, triads (usually from different disciplines cultural backgrounds) observe each other teaching, meet...
Hundreds of thousands astronomy education activities exist, but their discoverability and quality is highly variable. The web platform for activities, astroEDU, presented in this paper tries to solve these issues. Using the familiar peer-review workflow scientific publications, astroEDU improving standards quality, visibility accessibility, while providing credibility activities. targets activity guides, tutorials other educational area education, prepared by teachers, educators specialists....
The West African International Summer School for Young Astronomers (WAISSYA) is a week-long program university science students and teachers from Africa to develop their interest in astronomy. first summer school was held Abuja, Nigeria, 2013; the second Nsukka, July 2015. has large number of interested science, but paucity facilities or funding bodies developing Our broad goals WAISSYA are: (1) introduce astronomy; (2) exchange ideas about teaching learning abroad; (3) continue building...
A star that wanders too close to a massive black hole (BH) is shredded by the BH's tidal gravity. Stellar gas falls back BH, releasing flare of energy. In anticipation upcoming transient surveys, we predict light curves and spectra flares as function time, highlighting unique signatures in optical near-IR. Some initially bound BH likely blown away when fallback rate super-Eddington at early times. This outflow produces an luminosity comparable supernova (Figure 1, left panel); such events...