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- Keyword
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- Globular clusters: general (2)
- Methods: statistical (2)
- Astronautics (1)
- Astronomy (1)
- Circumstellar matter (1)
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- Clusters: individual (Hyades (1)
- Galaxies: individual (M31) (1)
- Galaxy: formation (1)
- Globular clusters: individual (NGC 5024 (1)
- Hertzsprung-Russell and colour-magnitude diagrams (1)
- M67 (1)
- Methods: data analysis (1)
- NGC 188 (1)
- NGC 2168 and NGC 2477) (1)
- NGC 2477 (1)
- NGC 2660 (1)
- NGC 3960) (1)
- NGC 5272 (1)
- NGC 6352) (1)
- Novae - cataclysmic variables (1)
- Open clusters and associations: general (1)
- Open clusters and associations: individual (NGC 2360 (1)
- Planetary systems (1)
- Spectroscopy (1)
- Stars: binaries (1)
- Stars: evolution (1)
- Stars: evolutions (1)
- Stars: fundamental parameters (1)
- Stars: individual (EC 20117-4014) (1)
- Stars: individual (M31N 2008-12a) (1)
- Publication Type
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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters Ii: Ngc 5024, Ngc 5272, And Ngc 6352, Rachel Wagner-Kaiser, Ted Von Hippel, David Stenning, Elliot Robinson, Ata Sarajedini, David Van Dyk, Nathan Stein, William H. Jefferys
Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters Ii: Ngc 5024, Ngc 5272, And Ngc 6352, Rachel Wagner-Kaiser, Ted Von Hippel, David Stenning, Elliot Robinson, Ata Sarajedini, David Van Dyk, Nathan Stein, William H. Jefferys
Publications
We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival ACS Treasury observations of Galactic Globular Clusters to find and characterize two stellar populations in NGC 5024 (M53), NGC 5272 (M3), and NGC 6352. For these three clusters, both single and double-population analyses are used to determine a best fit isochrone(s). We employ a sophisticated Bayesian analysis technique to simultaneously fit the cluster parameters (age, distance, absorption, and metallicity) that characterize each cluster. For the two-population analysis, unique population level helium values are also fit to each distinct population of the cluster and the relative proportions of the …
Expected And Achievable Accuracy In Estimating Parameters Of Standing Accretion Shock Instability (Sasi) Fluctuations From Neutrinos And Gravitational Wave Oscillations, Colter Richardson, Jonathan Westhouse
Expected And Achievable Accuracy In Estimating Parameters Of Standing Accretion Shock Instability (Sasi) Fluctuations From Neutrinos And Gravitational Wave Oscillations, Colter Richardson, Jonathan Westhouse
Undergraduate Research Symposium - Prescott
Core collapse supernovae are one of the most interesting sources of gravitational waves. When the progenitor star is particularly massive, hydrodynamic instability called standing accretion shock instability can develop and it is characterized by deterministic oscillations in the gravitational wave signal as well as in the neutrino luminosity with frequencies of 100hz. In this talk we will review current efforts to extract physical information from the SASI components of the gravitational wave and enhance the detectability of gravitational waves with such components both using laser interferometers and neutrino detectors.
Modeling And Detectability Of Gravitational Wave Waveform Memory From Core Collapse Supernovae, Pedro Jesus Quinonez, Emily Grimes
Modeling And Detectability Of Gravitational Wave Waveform Memory From Core Collapse Supernovae, Pedro Jesus Quinonez, Emily Grimes
Undergraduate Research Symposium - Prescott
Ever since the discovery of gravitational waves by LIGO, studying these waves have become of utmost importance. This is because gravitational waves have the potential to carry information that have remain unseen by physicist in the past. For example, take the case of a core collapse supernovae. Any information transferred through electromagnetic waves that attempts to escape the inner core of a dying star is blocked out by the intense radiation of its outer shell. For this reason, astronomers have been unable to truly study what goes in the core. However, this is not the case for gravitational waves, which …
A Bayesian Analysis Of The Ages Of Four Open Clusters, Elizabeth Jeffery, Ted Von Hippel, David A. Van Dyk, David C. Stenning, Elliot Robinson, Nathan Sten, William H. Jefferys
A Bayesian Analysis Of The Ages Of Four Open Clusters, Elizabeth Jeffery, Ted Von Hippel, David A. Van Dyk, David C. Stenning, Elliot Robinson, Nathan Sten, William H. Jefferys
Publications
In this paper we apply a Bayesian technique to determine the best fit of stellar evolution models to find the main sequence turn off age and other cluster parameters of four intermediate-age open clusters: NGC 2360, NGC 2477, NGC 2660, and NGC 3960. Our algorithm utilizes a Markov chain Monte Carlo technique to fit these various parameters, objectively finding the best-fit isochrone for each cluster. The result is a high-precision isochrone fit. We compare these results with the those of traditional “by-eye” isochrone fitting methods. By applying this Bayesian technique to NGC 2360, NGC 2477, NGC 2660, and NGC 3960, …
Dust Production And Depletion In Evolved Planetary Systems, J. Farihi, Ted Von Hippel, Rik Van Lieshout, P.W. Cauley, Erik Dennihy, Et Al.
Dust Production And Depletion In Evolved Planetary Systems, J. Farihi, Ted Von Hippel, Rik Van Lieshout, P.W. Cauley, Erik Dennihy, Et Al.
Publications
The infrared dust emission from the white dwarf GD 56 is found to rise and fall by 20 per cent peak-to-peak over 11.2 yr, and is consistent with ongoing dust production and depletion. It is hypothesized that the dust is produced via collisions associated with an evolving dust disc, temporarily increasing the emitting surface of warm debris, and is subsequently destroyed or assimilated within a few years. The variations are consistent with debris that does not change temperature, indicating that dust is produced and depleted within a fixed range of orbital radii. Gas produced in collisions may rapidly re-condense onto …
Bayesian Hierarchical Modelling Of Initial-Final Mass Relations Across Star Clusters, Shijing Si, David A. Van Dyk, Ted Von Hippel, Elliot Robinson, Elizabeth Jeffery, David C. Stenning
Bayesian Hierarchical Modelling Of Initial-Final Mass Relations Across Star Clusters, Shijing Si, David A. Van Dyk, Ted Von Hippel, Elliot Robinson, Elizabeth Jeffery, David C. Stenning
Publications
The initial-final mass relation (IFMR) of white dwarfs (WDs) plays an important role in stellar evolution. To derive precise estimates of IFMRs and explore how they may vary among star clusters, we propose a Bayesian hierarchical model that pools photometric data from multiple star clusters. After performing a simulation study to show the benefits of the Bayesian hierarchical model, we apply this model to five star clusters: the Hyades, M67, NGC 188, NGC 2168, and NGC 2477, leading to reasonable and consistent estimates of IFMRs for these clusters. We illustrate how a cluster-specific analysis of NGC 188 using its own …
Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters I: Statistical And Computational Methods, David Stenning, Ted Von Hippel, Rachel Wagner-Kaiser, Elliot Robinson, David Van Dyk, Ata Sarajedini, Nathan Stein
Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters I: Statistical And Computational Methods, David Stenning, Ted Von Hippel, Rachel Wagner-Kaiser, Elliot Robinson, David Van Dyk, Ata Sarajedini, Nathan Stein
Publications
We develop a Bayesian model for globular clusters composed of multiple stellar populations, extend- ing earlier statistical models for open clusters composed of simple (single) stellar populations (e.g., van Dyk et al. 2009; Stein et al. 2013). Specifically, we model globular clusters with two populations that differ in helium abundance. Our model assumes a hierarchical structuring of the parameters in which physical properties|age, metallicity, helium abundance, distance, absorption, and initial mass|are common to (i) the cluster as a whole or to (ii) individual populations within a cluster, or are unique to (iii) individual stars. An adaptive Markov chain Monte Carlo …
Orbital Characteristics Of The Subdwarf-B And F V Star Binary Ec 20117-4014 (=V4640 Sgr), T. Otani, T. D. Oswalt, A. E. Lynas-Gray, D. Kilkenny, C. Koen, M. Amaral, R. Jordan
Orbital Characteristics Of The Subdwarf-B And F V Star Binary Ec 20117-4014 (=V4640 Sgr), T. Otani, T. D. Oswalt, A. E. Lynas-Gray, D. Kilkenny, C. Koen, M. Amaral, R. Jordan
Publications
Among the competing evolution theories for subdwarf-B (sdB) stars is the binary evolution scenario. EC 20117-4014 (=V4640 Sgr) is a spectroscopic binary system consisting of a pulsating sdB star and a late F main-sequence companion; however, the period and the orbit semimajor axes have not been precisely determined. This paper presents orbital characteristics of the EC 20117-4014 binary system using 20 years of photometric data. Periodic observed minus calculated (O–C) variations were detected in the two highest-amplitude pulsations identified in the EC 20117-4014 power spectrum, indicating the binary system's precise orbital period (P = 792.3 …
Book Review: Spectral Atlas For Amateur Astronomers: A Guide To The Spectra Of Astronomical Objects And Terrestrial Light Sources, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of Spectral Atlas for Amateur Astronomers: A Guide to the Spectra of Astronomical Objects and Terrestrial Light Sources by Richard Walker. Cambridge 2017, 277 p bibl index, 9781107165908 $89.99, 9781316731048 $72.00
Breaking The Habit: The Peculiar 2016 Eruption Of The Unique Recurrent Nova M31n 2008-12a, M. Henze, T. D. Oswalt, M. J. Darnley, S. C. Williams, M. Kato, Et Al.
Breaking The Habit: The Peculiar 2016 Eruption Of The Unique Recurrent Nova M31n 2008-12a, M. Henze, T. D. Oswalt, M. J. Darnley, S. C. Williams, M. Kato, Et Al.
Publications
Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and …
Precise Ages Of Field Stars From White Dwarf Companions, M. Fouesneau, H-W. Rix, T. Von Hippel, D. W. Hogg, H. Tian
Precise Ages Of Field Stars From White Dwarf Companions, M. Fouesneau, H-W. Rix, T. Von Hippel, D. W. Hogg, H. Tian
Publications
Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star’s physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can be measured from spectroscopy, but ages are very hard to determine. The situation is different if the MS star has a white dwarf (WD) companion and a known distance, as the age of such a binary system can then be determined precisely from the photometric properties of the cooling WD. As a pilot study for obtaining precise age determinations of field MS stars, we identify …