Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
The 2d Distribution Of Iron-Rich Ejecta In The Remnant Of Sn 1885 In M31, Robert A. Fesen, Peter A. Höflich, Andrew J. S. Hamilton
The 2d Distribution Of Iron-Rich Ejecta In The Remnant Of Sn 1885 In M31, Robert A. Fesen, Peter A. Höflich, Andrew J. S. Hamilton
Dartmouth Scholarship
We present Hubble Space Telescope (HST) ultraviolet Fe i and Fe ii images of the remnant of Supernova 1885 (S And) which is observed in absorption against the bulge of the Andromeda galaxy, M31. We compare these Fe i and Fe ii absorption line images to previous HST absorption images of S And, of which the highest quality and theoretically cleanest is Ca ii H and K. Because the remnant is still in free expansion, these images provide a 2D look at the distribution of iron synthesized in this probable Type Ia explosion, thus providing insights and constraints …
Search For Higgs Shifts In White Dwarfs, Roberto Onofrio, Gary A. Wegner
Search For Higgs Shifts In White Dwarfs, Roberto Onofrio, Gary A. Wegner
Dartmouth Scholarship
We report on a search for differential shifts between electronic and vibronic transitions in carbon-rich white dwarfs BPM 27606 and Procyon B. The absence of differential shifts within the spectral resolution and taking into account systematic effects such as space motion and pressure shifts allows us to set the first upper bound of astrophysical origin on the coupling between the Higgs field and the Kreschmann curvature invariant. Our analysis provides the basis for a more general methodology to derive bounds to the coupling of long-range scalar fields to curvature invariants in an astrophysical setting complementary to the ones available from …
A Bayesian Approach To Deriving Ages Of Individual Field White Dwarfs, Erin M. O'Malley, Ted Von Hippel, David A. Van Dyk
A Bayesian Approach To Deriving Ages Of Individual Field White Dwarfs, Erin M. O'Malley, Ted Von Hippel, David A. Van Dyk
Dartmouth Scholarship
We apply a self-consistent and robust Bayesian statistical approach to determine the ages, distances, and zero-age main sequence (ZAMS) masses of 28 field DA white dwarfs (WDs) with ages of approximately 4-8 Gyr. Our technique requires only quality optical and near-infrared photometry to derive ages with <15% uncertainties, generally with little sensitivity to our choice of modern initial-final mass relation. We find that age, distance, and ZAMS mass are correlated in a manner that is too complex to be captured by traditional error propagation techniques. We further find that the posterior distributions of age are often asymmetric, indicating that the standard approach to deriving WD ages can yield misleading results.
The Fast And Furious Decay Of The Peculiar Type Ic Supernova 2005ek, M. R. Drout, A. M. Soderberg, P. A. Mazzali, J. T. Parrent
The Fast And Furious Decay Of The Peculiar Type Ic Supernova 2005ek, M. R. Drout, A. M. Soderberg, P. A. Mazzali, J. T. Parrent
Dartmouth Scholarship
We present extensive multi-wavelength observations of the extremely rapidly declining Type Ic supernova (SN Ic), SN 2005ek. Reaching a peak magnitude of MR = –17.3 and decaying by ~3 mag in the first 15 days post-maximum, SN 2005ek is among the fastest Type I supernovae observed to date. The spectra of SN 2005ek closely resemble those of normal SN Ic, but with an accelerated evolution. There is evidence for the onset of nebular features at only nine days post-maximum. Spectroscopic modeling reveals an ejecta mass of ~0.3 M ☉ that is dominated by oxygen (~80%), while the pseudo-bolometric light …
Subaru High-Resolution Spectroscopy Of Star G In The Tycho Supernova Remnant, Wolfgang E. Kerzendorf, Brian P. Schmidt, M. Asplund, Ken'ichi Nomoto, Ph. Podsiadlowski, Anna Frebel, Robert A. Fesen, David Yong
Subaru High-Resolution Spectroscopy Of Star G In The Tycho Supernova Remnant, Wolfgang E. Kerzendorf, Brian P. Schmidt, M. Asplund, Ken'ichi Nomoto, Ph. Podsiadlowski, Anna Frebel, Robert A. Fesen, David Yong
Dartmouth Scholarship
It is widely believed that Type Ia supernovae (SNe Ia) originate in binary systems where a white dwarf accretes material from a companion star until its mass approaches the Chandrasekhar mass and carbon is ignited in the white dwarf's core. This scenario predicts that the donor star should survive the supernova (SNe) explosion, providing an opportunity to understand the progenitors of SNe Ia. In this paper, we argue that rotation is a generic signature expected of most nongiant donor stars that is easily measurable. Ruiz-Lapuente et al. examined stars in the center of the remnant of SN 1572 (Tycho SN) …
New Neighbors: Parallaxes Of 18 Nearby Stars Selected From The Lspm-North Catalog, Sébastien Lépine, John R. Thorstensen, Michael M. Shara, R. Michael Rich
New Neighbors: Parallaxes Of 18 Nearby Stars Selected From The Lspm-North Catalog, Sébastien Lépine, John R. Thorstensen, Michael M. Shara, R. Michael Rich
Dartmouth Scholarship
We present astrometric parallaxes for 18 suspected nearby stars selected from the LSPM-north proper motion catalog. 16 objects are confirmed to be main-sequence M dwarfs within 16 pc of the Sun, including three stars (LSPM J0011+5908, LSPM J0330+5413, and LSPM J0510+2714) which lie just within the 10 pc horizon. Two other targets (LSPM J1817+1328, LSPM J2325+1403) are confirmed to be nearby white dwarfs at distances of 14 and 22 pc, respectively. One of our targets, the common proper motion pair LSPM J0405+7116E + LSPM J0405+7116W, is revealed to be a triple system, with the western component resolved into a pair …
De Canum Venaticorum: A Bright, Eclipsing Red Dwarf–White Dwarf Binary, E. J. M. Van Den Besselaar, R. Greimel, L. Morales-Rueda, G. Nelemans, J. R. Thorstensen
De Canum Venaticorum: A Bright, Eclipsing Red Dwarf–White Dwarf Binary, E. J. M. Van Den Besselaar, R. Greimel, L. Morales-Rueda, G. Nelemans, J. R. Thorstensen
Dartmouth Scholarship
Close white dwarf - red dwarf binaries must have gone through a common-envelope phase during their evolution. DE CVn is a detached white dwarf - red dwarf binary with a relatively short (~8.7 hours) orbital period. Its brightness and the presence of eclipses makes this system ideal for a more detailed study. From a study of photometric and spectroscopic observations of DE CVn we derive the system parameters which we discuss in the frame work of common-envelope evolution. Photometric observations of the eclipses are used to determine an accurate ephemeris. From a model fit to an average low-resolution spectrum of …
Hs 2331+3905: The Cataclysmic Variable That Has It All, S. Araujo-Betancor, B. T. Gänsicke, H.-J. Hagen, T. R. Marsh, E T. Harlaftis, J Thorstensen
Hs 2331+3905: The Cataclysmic Variable That Has It All, S. Araujo-Betancor, B. T. Gänsicke, H.-J. Hagen, T. R. Marsh, E T. Harlaftis, J Thorstensen
Dartmouth Scholarship
We report detailed follow-up observations of the cataclysmic variable HS 2331+3905, identified as an emission- line object in the Hamburg Quasar Survey. An orbital period of 81.08 min is unambiguously determined from the detection of eclipses in the light curves of HS 2331+3905. A second photometric period is consistently detected at P ≃ 83.38 min, ∼2.8% longer than Porb, which we tentatively relate to the presence of permanent superhumps. High time resolution photometry exhibits short-timescale variability on time scales of ≃5−6 min which we interpret as non-radial white dwarf pulsations, as well as a coherent signal at 1.12 min, which …
Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner
Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner
Dartmouth Scholarship
A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case …