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Articles 1 - 8 of 8
Full-Text Articles in Astrophysics and Astronomy
A Trip To The Cataclysmic Binary Zoo: Detailed Follow-Up Of 35 Recently Discovered Systems, John R. Thorstensen, Erek H. Alper, Kathryn E. Weil
A Trip To The Cataclysmic Binary Zoo: Detailed Follow-Up Of 35 Recently Discovered Systems, John R. Thorstensen, Erek H. Alper, Kathryn E. Weil
Dartmouth Scholarship
We report follow-up studies of 35 recently discovered cataclysmic variables (CVs), 32 of which were found in large, automated synoptic sky surveys. The objects were selected for observational tractability. For 34 of the objects, we present mean spectra and spectroscopic orbital periods, and for one more we give an eclipse-based period. Thirty-two of the period determinations are new, and three of these refine published estimates based on superhump periods. The remaining three of our determinations confirm previously published periods. Twenty of the stars are confirmed or suspected dwarf novae with periods shorter than 3 hr, but we also find three …
Hubble Space Telescopeconstraints On The Winds And Astrospheres Of Red Giant Stars, Brian E. Wood, Hans-Reinhard Müller, Graham M. Harper
Hubble Space Telescopeconstraints On The Winds And Astrospheres Of Red Giant Stars, Brian E. Wood, Hans-Reinhard Müller, Graham M. Harper
Dartmouth Scholarship
We report on an ultraviolet spectroscopic survey of red giants observed by the Hubble Space Telescope, focusing on spectra of the Mg ii h and k lines near 2800 Å in order to study stellar chromospheric emission, winds, and astrospheric absorption. We focus on spectral types between K2 III and M5 III, a spectral type range with stars that are noncoronal, but possessing strong, chromospheric winds. We find a very tight relation between Mg ii surface flux and photospheric temperature, supporting the notion that all K2-M5 III stars are emitting at a basal flux level. Wind velocities (V …
A Multi-Wavelength Analysis Of Cold Evolving Interstellar Clouds, Mary Spraggs
A Multi-Wavelength Analysis Of Cold Evolving Interstellar Clouds, Mary Spraggs
Mahurin Honors College Capstone Experience/Thesis Projects
The interstellar medium (ISM) is the dynamic system of gas and dust that fills the space between the stars within galaxies. Due to its integral role in star formation and ga-lactic structure, it is important to understand how the ISM itself evolves over time, in-cluding the process of cooling and condensing required to form new stars. This work aims to constrain and better understand the physical properties of the cold ISM with sev-eral different types of data, including large surveys of neutral atomic hydrogen (HI) 21cm spectral line emission and absorption, carbon monoxide (CO) 2.6mm line emission, and multi-band infrared …
Flickering Analysis Of Ch Cygni Using Kepler Data, Thomas Holden Dingus
Flickering Analysis Of Ch Cygni Using Kepler Data, Thomas Holden Dingus
Undergraduate Honors Theses
Utilizing data from the Kepler Mission, we analyze a flickering phenomenon in the symbiotic variable star CH Cygni. We perform a spline interpolation of an averaged lightcurve and subtract the spline to acquire residual data. This allows us to analyze the deviations that are not caused by the Red Giant’s semi-regular periodic variations. We then histogram the residuals and perform moment calculations for variance, skewness, and kurtosis for the purpose of determining the nature of the flickering. Our analysis has shown that we see a much smaller scale flickering than observed in the previous literature. Our flickering scale is on …
Constraining The Age And Distance Of The Galactic Supernova Remnant G156.2+5.7 By H A Expansion Measurements, Satoru Katsuda, Masaomi Tanaka, Tomoki Morokuma, Robert Fesen, Dan Milisavljevic
Constraining The Age And Distance Of The Galactic Supernova Remnant G156.2+5.7 By H A Expansion Measurements, Satoru Katsuda, Masaomi Tanaka, Tomoki Morokuma, Robert Fesen, Dan Milisavljevic
Dartmouth Scholarship
We present deep Hα images of portions of the X-ray bright, but optically faint, Galactic supernova remnant G156.2+5.7, revealing numerous and delicately thin non-radiative filaments, which mark the location of the remnant's forward shock. These new images show that these filaments have a complex structure not visible on previous lower resolution optical images. By comparing Hα images taken in 2004 at the McDonald Observatory and in 2015–2016 at the Kiso Observatory, we set a stringent 1σ upper limit of expansion to be 0.06 arcsec/yr. This proper motion, combined with a shock speed of 500 km s−1 …
Population Properties Of Brown Dwarf Analogs To Exoplanets, Jacqueline K. Faherty, Adric R. Riedel, Kelle L. Cruz, Jonathan Gagne, Joseph C. Filippazzo, Erini Lambrides, Haley Fica, Alycia Weinberger, John R. Thorstensen
Population Properties Of Brown Dwarf Analogs To Exoplanets, Jacqueline K. Faherty, Adric R. Riedel, Kelle L. Cruz, Jonathan Gagne, Joseph C. Filippazzo, Erini Lambrides, Haley Fica, Alycia Weinberger, John R. Thorstensen
Dartmouth Scholarship
We present a kinematic analysis of 152 low surface gravity M7-L8 dwarfs by adding 18 new parallaxes (including 10 for comparative field objects), 38 new radial velocities, and 19 new proper motions. We also add low- or moderate-resolution near-infrared spectra for 43 sources confirming their low surface gravity features. Among the full sample, we find 39 objects to be high-likelihood or new bona fide members of nearby moving groups, 92 objects to be ambiguous members and 21 objects that are non-members. Using this age-calibrated sample, we investigate trends in gravity classification, photometric color, absolute magnitude, color–magnitude, luminosity, and effective temperature. …
Comparative Analysis Of Sn 2012dn Optical Spectra:Days −14 To +114, J. T. Parrent, D. A. Howell, R. A. Fesen, S. Parker
Comparative Analysis Of Sn 2012dn Optical Spectra:Days −14 To +114, J. T. Parrent, D. A. Howell, R. A. Fesen, S. Parker
Dartmouth Scholarship
SN 2012dn is a super-Chandrasekhar mass candidate in a purportedly normal spiral (SAcd) galaxy, and poses a challenge for theories of type Ia supernova diversity. Here we utilize the fast and highly parametrized spectrum synthesis tool, SYNAPPS, to estimate relative expansion velocities of species inferred from optical spectra obtained with six facilities. As with previous studies of normal SN Ia, we find that both unburned carbon and intermediate-mass elements are spatially coincident within the ejecta near and below 14 000 km s−1. Although the upper limit on SN 2012dn's peak luminosity is comparable to some of the most …
Modeling Extrasolar Trojan Asteroids In Gravitational Potentials Of Migrating Jovian-Like Planets To Inform Future Observations, Austin Hinkel
Modeling Extrasolar Trojan Asteroids In Gravitational Potentials Of Migrating Jovian-Like Planets To Inform Future Observations, Austin Hinkel
Lewis Honors College Capstone Collection
In this paper, I construct a program to map the evolution of the potential in a planet-star system where a planet with a few Jupiter masses migrates inward. Given a trojan asteroid librating around the fourth or fifth Lagrange point, the asteroid follows the evolving equipotential lines of the slowly changing potential map. As the planet and its trojan asteroids migrate inward towards the host star, the trojan asteroid librations become tighter, providing a denser “cloud” of trojan asteroids. Such a change in the density of trojan asteroids is examined with the intent to deduce the likelihood of detection via …