A5028296117- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Space Science and Extraterrestrial Life
- Neural dynamics and brain function
- Pulsars and Gravitational Waves Research
- Visual perception and processing mechanisms
- Astronomical Observations and Instrumentation
- CCD and CMOS Imaging Sensors
- Radio Astronomy Observations and Technology
- Planetary Science and Exploration
- Memory and Neural Mechanisms
- Astrophysics and Cosmic Phenomena
- Space exploration and regulation
- Galaxies: Formation, Evolution, Phenomena
- Advanced Mathematical Theories and Applications
- Metaheuristic Optimization Algorithms Research
University of California, Los Angeles
2022-2023
California Institute of Technology
2023
Astronomy and Space
2022
We report discovery and spectroscopic follow-up of 21 astrometric binaries containing solar-type stars dark companions with masses near 1.4 $M_{\odot}$. The simplest interpretation is that the are dormant neutron (NSs), though ultramassive white dwarfs (WDs) tight WD+WD cannot be fully excluded. selected targets from Gaia DR3 binary solutions in which luminous star on main sequence dynamically-implied mass unseen companion (a) more than $1.25\,M_{\odot}$ (b) too high to any non-degenerate or...
ABSTRACT Post-common envelope binaries (PCEBs) containing a white dwarf (WD) and main-sequence (MS) star can constrain the physics of common evolution calibrate binary models. Most PCEBs studied to date have short orbital periods (Porb ≲ 1 d), implying relatively inefficient harnessing binaries’ energy for expulsion. Here, we present follow-up observations five from 3rd data release Gaia mission solar-type MS stars probable ultramassive WDs ($M\gtrsim 1.2\ {\rm M}_{\odot}$) with...
We report a spectroscopic search for hypervelocity white dwarfs (WDs) that are runaways from Type Ia supernovae (SNe Ia) and related thermonuclear explosions. Candidates selected Gaia data with high tangential velocities blue colors. find six new runaways, including four stars radial (RVs) $>1000\,\rm km\,s^{-1}$ total space $\gtrsim 1300\,\rm km\,s^{-1}$. These most likely the surviving donors double-degenerate binaries in which other WD exploded. The two objects have lower minimum...
Five self-lensing binaries (SLBs) have been discovered with data from the \textit{Kepler} mission. One of these systems is KIC 8145411, which was reported to host an extremely low mass (ELM; $0.2\,M_{\odot}$) white dwarf (WD) in a 456-day orbit solar-type companion. The system has dubbed "impossible", because evolutionary models predict that $\sim 0.2\,M_{\odot}$ WDs should only be found tight orbits ($P_{\rm orb} \lesssim$ days). In this work, we show 8145411 fact hierarchical triple...
We report discovery and spectroscopic follow-up of 21 astrometric binaries containing solar-type stars dark companions with masses near 1.4 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>M</mml:mi><mml:mo>⊙</mml:mo></mml:msub></mml:math>. The simplest interpretation is that the are dormant neutron (NSs), though ultramassive white dwarfs (WDs) tight WD+WD cannot be fully excluded. selected targets from Gaia DR3 binary solutions in which luminous...
Astrometry from {\it Gaia} DR3 has enabled the discovery of a sample 3000+ binaries containing white dwarfs (WD) and main-sequence (MS) stars in relatively wide orbits, with orbital periods $P_{\rm orb} = (100-1000)$ d. This population was not predicted by binary synthesis models before -- if orbits are robust likely requires very efficient envelope ejection during common evolution (CEE). To assess reliability solutions, we measured multi-epoch radial velocities (RVs) 31 WD+MS candidates...
Abstract Astrometry from Gaia DR3 has enabled the discovery of a sample 3000+ binaries containing white dwarfs (WD) and main-sequence (MS) stars in relatively wide orbits, with orbital periods P orb = (100–1000) days. This population was not predicted by binary synthesis models before and—if orbits are robust—likely requires very efficient envelope ejection during common evolution (CEE). To assess reliability solutions, we measured multi-epoch radial velocities (RVs) 31 WD+MS candidates...
Abstract Five self-lensing binaries (SLBs) have been discovered with data from the Kepler mission. One of these systems is KIC 8145411, which was reported to host an extremely low mass (ELM; 0.2 M ⊙ ) white dwarf (WD) in a 456 days orbit solar-type companion. The system has dubbed “impossible,” because evolutionary models predict that ∼0.2 WDs should only be found tight orbits ( P orb ≲ days). In this work, we show 8145411 fact hierarchical triple system: it contains WD orbiting star,...
ABSTRACT One of the key processes driving galaxy evolution during Cosmic Dawn is supernova feedback. This likely helps regulate star formation inside galaxies, but it can also drive winds that influence large-scale intergalactic medium. Here, we present a simple semi-analytic model supernova-driven galactic and explore contributions different phases to cosmic metal enrichment in high-redshift (z ≳ 6) Universe. We show models calibrated observed luminosity function at z ∼ 6–8 have filling...
Abstract We conducted a search for narrowband radio signals over four observing sessions in 2020–2023 with the L -band receiver (1.15–1.73 GHz) of 100 m diameter Green Bank Telescope. pointed telescope directions 62 TESS Objects Interest, capturing emissions from total ∼11,680 stars and planetary systems ∼9′ beam telescope. All detections were either automatically rejected or visually inspected confirmed to be anthropogenic nature. also quantified end-to-end efficiency SETI pipelines signal...
ABSTRACT We present follow-up spectroscopy of 21 cataclysmic variables (CVs) with evolved secondaries and ongoing or recently terminated mass transfer. Evolutionary models predict that the should have anomalous surface abundances owing to nuclear burning in their cores during main-sequence evolution subsequent envelope stripping by companion white dwarfs. To test these models, we measure sodium (Na) donors from Fraunhofer ‘D’ doublet. Accounting for interstellar absorption, find all objects...
Post-common-envelope binaries (PCEBs) containing a white dwarf (WD) and main-sequence (MS) star can constrain the physics of common envelope evolution calibrate binary models. Most PCEBs studied to date have short orbital periods ($P_{\rm orb} \lesssim 1\,$d), implying relatively inefficient harnessing binaries' energy for expulsion. Here, we present follow-up observations five from {\it Gaia} DR3 solar-type MS stars probable ultramassive WDs ($M\gtrsim 1.2\,M_{\odot}$) with significantly...
Abstract Visual perception plays a critical role in navigating 3D space and extracting semantic information crucial to survival. Even though visual stimulation on the retina is fundamentally 2D, we seem perceive world around us vivid effortlessly. This reconstructed allocentric faithfully represents external world. How can recreate stable so promptly reliably? To solve this mystery, have developed new concepts MePMoS (Memory-Prediction-Motion-Sensing) NHT (Neural Holography Tomography)....
Five self-lensing binaries (SLBs) have been discovered with Kepler light curves. They contain white dwarfs (WDs) in AU-scale orbits that gravitationally lens solar-type companions. Forming SLBs likely requires common envelope evolution when the WD progenitor is an AGB star and has a weakly bound envelope. No yet data from Transiting Exoplanet Survey Satellite (TESS), which observes far more stars than did. Identifying TESS made challenging by fact only most for $\sim$25 days at time, so...
Abstract We measure the mass distribution of main-sequence (MS) companions to hot subdwarf B stars (sdBs) in post-common envelope binaries (PCEBs). carried out a spectroscopic survey 14 eclipsing systems (“HW Vir binaries”) with orbital periods 3.8 < P orb 12 hr, resulting well-understood selection function and near-complete sample HW G 16. constrain companion masses from radial velocity curves sdB stars. The peaks at M MS ≈ 0.15 ⊙ drops off > 0.2 , only two hosting above fully...
Abstract Five self-lensing binaries (SLBs) have been discovered with Kepler light curves. They contain white dwarfs (WDs) in AU-scale orbits that gravitationally lens solar-type companions. Forming SLBs likely requires common envelope evolution when the WD progenitor is an AGB star and has a weakly bound envelope. No yet data from Transiting Exoplanet Survey Satellite (TESS), which observes far more stars than did. Identifying TESS made challenging by fact only most for ∼25 days at time, so...
Abstract Visual perception plays a critical role in navigating space and extracting useful semantic information crucial to survival. To identify distant landmarks, we constantly shift gaze vectors through saccades, while still maintaining the visual of stable allocentric space. How can sustain so effortlessly? solve this question, have developed new concept NHT (Neural Holography Tomography). This model states that retinotopy is invisible (not available consciousness) must be converted time...
One of the key processes driving galaxy evolution during Cosmic Dawn is supernova feedback. This likely helps regulate star formation inside galaxies, but it can also drive winds that influence large-scale intergalactic medium. Here, we present a simple semi-analytic model supernova-driven galactic and explore contributions different phases to cosmic metal enrichment in high-redshift (z > 6) Universe. We show models calibrated observed luminosity function at z~6-8 have filling factors ~1%...
We present follow-up spectroscopy of 21 cataclysmic variables (CVs) with evolved secondaries and ongoing or recently-terminated mass transfer. Evolutionary models predict that the should have anomalous surface abundances owing to nuclear burning in their cores during main-sequence evolution subsequent envelope stripping by companion white dwarfs. To test these models, we measure sodium (Na) donors from Fraunhofer "D" doublet. Accounting for interstellar absorption, find {\it all} objects our...
We report a spectroscopic search for hypervelocity white dwarfs (WDs) that are runaways from Type Ia supernovae (SNe Ia) and related thermonuclear explosions. Candidates selected Gaia data with high tangential velocities blue colors. find six new runaways, including four stars radial (RVs) $>1000\,\rm km\,s^{-1}$ total space $\gtrsim 1300\,\rm km\,s^{-1}$. These most likely the surviving donors double-degenerate binaries in which other WD exploded. The two objects have lower minimum...
We conducted a search for narrowband radio signals over four observing sessions in 2020-2023 with the L-band receiver (1.15-1.73 GHz) of 100 m diameter Green Bank Telescope. pointed telescope directions 62 TESS Objects Interest, capturing emissions from total ~11,680 stars and planetary systems ~9 arcminute beam telescope. All detections were either automatically rejected or visually inspected confirmed to be anthropogenic nature. In this work, we also quantified end-to-end efficiency SETI...