A5021019961- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Marine and coastal plant biology
- History and Developments in Astronomy
- Fish Ecology and Management Studies
- Space Exploration and Technology
- Scientific Research and Discoveries
- Avian ecology and behavior
- High-pressure geophysics and materials
Harvard University
2015-2019
Center for Astrophysics Harvard & Smithsonian
2015-2019
University of California, Santa Cruz
2014-2015
University of California, Berkeley
2011-2013
Jeonbuk National University
2009
This is the first of a series papers presenting Modules for Experiments in Stellar Astrophysics (MESA) Isochrones and Tracks (MIST) project, new comprehensive set stellar evolutionary tracks isochrones computed using MESA, state-of-the-art open-source 1D evolution package. In this work, we present models with solar-scaled abundance ratios covering wide range ages ($5 \leq \rm \log(Age)\;[yr] 10.3$), masses ($0.1 M/M_{\odot} 300$), metallicities ($-2.0 [Z/H] 0.5$). The are self-consistently...
We present the initial-final mass relation (IFMR) based on self-consistent analysis of Sirius B and 79 white dwarfs from 13 star clusters. have also acquired additional signal eight previously analyzed in NGC 2099 cluster field, four which are consistent with membership. These reobserved masses ranging 0.72 to 0.97 M$_\odot$, initial 3.0 3.65 where IFMR has an important change slope that these new data help observationally confirm. In total, this directly measured small scatter ($\sigma$ =...
We present results from modeling the optical spectra of a large sample quiescent galaxies between 0.1 < z 0.7 Sloan Digital Sky Survey (SDSS) and AGN Galaxy Evolution (AGES). examine how stellar ages abundance patterns evolve over time as function mass 109.6–1011.8 M☉. are stacked in bins redshift modeled wavelength range 4000 Å to 5500 Å. Full spectrum population synthesis provides estimates age abundances elements Fe, Mg, C, N, Ca. find negligible evolution elemental at fixed roughly 7 Gyr...
The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by Kepler mission. In order to determine black hole mass in from H-beta reverberation mapping, we have carried out nightly observations with Kast Spectrograph at Lick 3m telescope during dark runs June through December 2010, obtaining 54 spectroscopic total. We also obtained V-band imaging Katzman Automatic Imaging Telescope Observatory and 0.9m Brigham Young University West Mountain over same period....
Abstract The Hyades, Praesepe, and Pleiades are well-studied stellar clusters that anchor important secondary age indicators. Recent studies have shown main sequence turn off based ages for these may depend on the degree of rotation in underlying models. Rotation induces structural instabilities can enhance chemical mixing a star, extending its fuel supply. In addition, introduces modulation star’s observed magnitude color due to effects gravity darkening. We aim investigate extent which...
Observations of young open clusters show a bimodal distribution rotation periods that has been difficult to explain with existing stellar spin-down models. Detailed MHD wind simulations have demonstrated surface magnetic field morphology strong influence on wind-driven angular momentum loss. suggest faster rotating stars store larger fraction their flux in higher-order multipolar components the field. In this work, we present new model for that, first time, accounts configuration. We how...
We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during 25 years between 1987 2012. The early precision was 20 \ms{} but 2 last 8 years, constituting most extensive sensitive search for signatures planets around this stellar neighbor. carefully analyze 136 radial velocities spanning by first applying a periodogram analysis nearly circular orbits. find no significant periodic signals with...
Abstract We investigate the integrated properties of massive ( <?CDATA $\gt 10\,{M}_{\odot }$?> ) rotating single-star stellar populations for a variety initial rotation rates $v/{v}_{\mathrm{crit}}=0.0$?> , 0.2, 0.4, 0.5, and 0.6). couple new MESA Isochrone Stellar Tracks (MIST) models to Flexible Population Synthesis (FSPS) package, extending population synthesis include contributions from very stars 100\,{M}_{\odot ), which can be significant in first ∼4 Myr after starburst. These predict...
Motivated by the recent, serendipitous discovery of densest known galaxy, M60-UCD1, we present two initial findings from a follow-up search, using Sloan Digital Sky Survey, Subaru/Suprime-Cam and Hubble Space Telescope imaging, SOuthern Astrophysical Research (SOAR)/Goodman spectroscopy. The first object discovered, M59-UCD3, has similar size to M60-UCD1 (half-light radius r_h ~ 20 pc) but is 40% more luminous (M_V -14.6), making it new densest-known galaxy. second, M85-HCC1, like typical...
Abstract The effective temperature ( T eff ) distribution of stellar evolution models along the red giant branch (RGB) is sensitive to a number parameters including overall metallicity, elemental abundance patterns, efficiency convection, and treatment surface boundary condition (BC). Recently there has been interest in using observational estimates RGB place constraints on mixing length parameter, α MLT , possible variation with metallicity. Here we use 1D Modules for Experiments Stellar...
Abstract Early-type galaxies (ETGs) frequently show emission from warm ionized gas. These low-ionization regions (LIERs) were originally attributed to a central, low-luminosity active galactic nucleus. However, the recent discovery of spatially extended LIER suggests ionization by both central source and an component that follows stellar-like radial distribution. For passively evolving with old stellar populations, hot post-asymptotic giant branch (AGB) stars are only viable ionizing...
We use the framework developed as part of MESA Isochrones and Stellar Tracks (MIST) project to assess utility several types observables in jointly measuring age 1D stellar model parameters star clusters. begin with a pedagogical overview summarizing effects parameters, such helium abundance, mass-loss efficiency, mixing length parameter, on observational diagnostics including color-magnitude diagram, mass-radius relation, surface abundances, amongst others. find that these influence...
Abstract The semi-empirical initial–final mass relation (IFMR) connects spectroscopically analyzed white dwarfs (WDs) in star clusters to the initial masses of stars that formed them. Most current stellar evolution models, however, predict will evolve WDs ∼0.1 M ⊙ less massive than found IFMR. We first look at how varying theoretical mass-loss rates, third dredge-up efficiencies, and convective-core overshoot may help explain differences between models observations. These parameters play an...
Abstract Stellar population synthesis models have long struggled to reproduce observed optical through near-IR (NIR) spectral energy distributions (SEDs) of massive quiescent galaxies. We revisit this issue using a novel approach that combines the diagnostic power full-spectrum fitting with recently updated stellar libraries. First, we perform continuum-normalized, stacked SDSS spectra in bins velocity dispersion infer their properties, such as elemental abundances and age. Next, use...
We report on the RXTE detection of a sudden increase in absorption column density, NH, during 2011 May outburst GX 304−1. The NH increased up to ∼16 × 1022 atoms cm−2, which is factor 3–4 larger than what usually measured outbursts 304−1 as covered by RXTE. Additionally, an variability hardness ratio calculated from energy resolved RXTE-Proportional Counter Array light curves this time range. interpret these facts occultation event neutron star material line sight. Using simple 3D model...
The Wintering Waterbird Census of Korea was started in 1999 and monitors 200 major migratory sites South Korea. Waterfowl counts have been undertaken for more than 20 years since; however, a limited number studies analyzed the temporal patterns waterfowl population. In this study, we population size changes wintering whooper swan (Cygnus cygnus) at 112 monitoring from 2001 to 2018. average swans 4,296±42.66 there trend an increase across survey period. We found that Nakdong River Estuary,...
In order to determine color excess in the <TEX>$uvby\beta$</TEX> system for high amplitude <TEX>$\delta$</TEX> Scuti stars, reddening free <TEX>$[m_1]$</TEX>, <TEX>$[c_1]$</TEX>, and <TEX>$\beta$</TEX> indices data were obtained from existing literature 21 stars. Then, three intrinsic relations of <TEX>$(b-y)_0$</TEX> - investigated. Among these, it was shown that <TEX>$(b-y)_0$</TEX>-<TEX>$[c_1]$</TEX> relation is most useful. By establishing six calibration excesses other stars determined.