A5052103497- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Scientific Research and Discoveries
- X-ray Spectroscopy and Fluorescence Analysis
- History and Developments in Astronomy
- Cosmology and Gravitation Theories
- Laser-Plasma Interactions and Diagnostics
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Optical Systems and Laser Technology
American Museum of Natural History
2017-2024
University of Toronto
2024
Haverford College
2023
Stony Brook University
2023
Dalton School
2017
ABSTRACT Just 10 recurrent novae (RNe) – which erupt repeatedly on time-scales shorter than one century are known in our Galaxy. The most extreme RN (located the Andromeda galaxy), M31N 2008-12a, undergoes a nova eruption every year, and is surrounded by vast ‘super-remnant’, 134 pc extent. Simulations predict that all RNe should be similar shells, but previous searches have failed to detect them. KT Eri has recently been suggested RN, we used Condor Array Telescope image its environs...
ABSTRACT The existence of a vast nova shell surrounding the prototypical dwarf Z Camelopardalis (Z Cam) proves that some old novae undergo metamorphosis to appear as thousands years after eruption. expansion rates ancient shells offer way constrain both time between eruptions and for post-nova mass transfer decrease significantly, simultaneously testing thermonuclear runaway models hibernation theory. Previous limits on rate part Cam inter-eruption events be >1300 yr. Deeper...
In this paper, the third in series, we continue our study of combinatorics chaotic Newtonian dynamics. We four-body problem gravity assuming finite-sized particles, and focus on interactions that produce direct collisions between any two stars. Our long-term goal is to construct an equation gives probability a given collision event occurring over course interaction, as function total encounter energy angular momentum well numbers properties particles. previous papers, varied number...
ABSTRACT Gas-rich galaxies are typically star forming. We make use of H i-MaNGA, a programme i follow-up for the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey Sloan Digital Sky Surveys, to construct sample unusual neutral hydrogen (H i, 21 cm)-rich that have low formation rates (SFRs), using infrared colour from Wide-field Infrared Survey Explorer as proxy specific SFR. Out set 1575 MaNGA with i-MaNGA detections, we find 83 (5 per cent) meet our selection criteria be...
ABSTRACT We evaluate recent and upcoming low-redshift neutral hydrogen (H i) surveys as a cosmological probe of small scale structure with goal determining the survey criteria necessary to test ultralight axion (ULA) dark matter models. Standard cold (CDM) models predict large population low-mass galactic haloes, whereas ULA demonstrate significant suppression in this small-scale regime, halo mass cutoffs $10^{12}\, \mathrm{M}_{\odot }$ $10^{7}\, corresponding masses $10^{-24}\,$...
Abstract A century or less separates the thermonuclear-powered eruptions of recurrent novae (RNe) in hydrogen-rich envelopes massive white dwarfs. The colliding ejecta successive RN events are predicted to always generate very large (tens parsecs) super-remnants; only two examples currently known. T CrB offers an excellent opportunity test this prediction. As it will almost certainly undergo its next, once ∼80 yr event between 2024 and 2026, we carried out deep narrowband continuum imaging...
ABSTRACT We used the Condor array telescope to obtain deep imaging observations through luminance filter of entirety NGC 5866 Group, including a very extended region surrounding galaxy 5907 and its stellar stream. find that stream consists single curved structure stretches 220 kpc from brighter eastern fainter western bends north then curls back toward galaxy. This result runs contrary previous claim second loop but is consistent with another description overall morphology further that: (1)...
ABSTRACT A nova super-remnant (NSR) is an immense structure associated with a that forms when frequent and recurrent (RN) eruptions sweep up surrounding interstellar medium (ISM) into high-density distant shell. The prototypical NSR, measuring over 100 pc across, was discovered in 2014 around the annually erupting M 31N 2008-12a. Hydrodynamical simulations demonstrated creation of dynamic NSR by repeated transporting large quantities ISM not only feasible but these structures should exist...
Just 10 recurrent novae (RNe) - which erupt repeatedly on timescales shorter than one century are known in our Galaxy. The most extreme RN (located the Andromeda galaxy), M31N 2008-12a, undergoes a nova eruption every year, and is surrounded by vast "super-remnant", 134 pc extent. Simulations predict that all RNe should be similar shells, but previous searches have failed to detect them. KT Eri has recently been suggested RN, we used Condor Array Telescope image its environs through multiple...
Ten weeks of daily imaging the giant elliptical galaxy M87 with Hubble Space Telescope (HST) has yielded 41 nova light curves unprecedented quality for extragalactic cataclysmic variables. We have recently used these to demonstrate that observational scatter in so-called Maximum-Magnitude Rate Decline (MMRD) relation classical novae is so large as render nova-MMRD useless a standard candle. Here we modified Buscombe - de Vaucouleurs hypothesis, namely decline times t2 > 10 days converge...
We evaluate recent and upcoming low-redshift neutral hydrogen (HI) surveys as a cosmological probe of small scale structure with goal determining the survey criteria necessary to test ultra-light axion (ULA) dark matter models. Standard cold (CDM) models predict large population low-mass galactic halos, whereas ULA demonstrate significant suppression in this small-scale regime, halo mass cutoffs $10^{12}\, \mathrm{M}_{\odot}$ $10^{7}\, corresponding masses $10^{-24}\,$eV $10^{-20}\,$eV,...
Classical nova eruptions result from thermonuclear-powered runaways in, and ejection of, the hydrogen-rich envelopes of white dwarf stars accreted their close binary companions. Novae brighten to up 1,000,000 solar luminosities, recur thousands times over lifetimes spanning several billion years. Between eruptions, mass transfer donor star proceeds via an accretion disk unless possesses a strong magnetic field which can partially or totally disrupt disk. In that case, is focussed by dwarf's...
ABSTRACT Accurately quantifying the rates dM/dt at which massive stars lose mass is essential to any understanding of their evolution. All estimates date assume wind clumping factors; not allowing for leads overestimates and underestimates lifetimes masses when these explode as supernovae. Mid-infrared spectroscopy suggested that nearest Wolf–Rayet (WR) star, γ2 Vel, resolved with a full width 10 per cent intensity 0.5 arcsec, or 171 au 342 pc distance star. As Zorro speckle imager on Gemini...
We used the Condor Array Telescope to obtain deep imaging observations through luminance filter of entirety NGC 5866 Group, including a very extended region surrounding galaxy 5907 and its stellar stream. find that stream consists single curved structure stretches $220$ kpc from brighter eastern fainter western bends north then curls back toward galaxy. This result runs contrary previous claim second loop but is consistent with another description overall morphology further that: (1) an...
Accurately quantifying the rates dM/dt at which massive stars lose mass is essential to any understanding of their evolution. All estimates date assume wind clumping factors; not allowing for leads overestimates and underestimates lifetimes masses when these explode as supernovae. Mid-IR spectroscopy suggested that nearest Wolf-Rayet star, Gamma2 Vel, resolved with a Full Width 10 per cent intensity 0.5 arcsec, or 171 AU 342 pc distance star. As Zorro speckle imager on Gemini-South capable...
Gas rich galaxies are typically star-forming. We make use of HI-MaNGA, a program HI follow-up for the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey Sloan Digital Sky Surveys to construct sample unusual neutral hydrogen (HI, 21cm) which have low Star Formation Rates (SFRs); using infra-red color from Wide-field Infrared Survey Explorer (WISE) as proxy specific SFR. Out set 1575 MaNGA with HI-MaNGA detections, we find 83 (5%) meet our selection criteria be two stellar...
A nova super-remnant (NSR) is an immense structure associated with a that forms when frequent and recurrent eruptions sweep up surrounding interstellar material (ISM) into high density distant shell. The prototypical NSR, measuring over 100 pc across, was discovered in 2014 around the annually erupting M31N 2008-12a. Hydrodynamical simulations demonstrated creation of dynamic NSR by repeated transporting large quantities ISM not only feasible but these structures should exist all novae,...