Physical Sciences and Mathematics Commons^™

Bayesian Inference For The White Dwarf Initial-Final Mass Relation, Nathan Stein, Ted Von Hippel, David Van Dyk, Steven Degennaro, Elizabeth Jeffery, Bill Jefferys

Publications

Stars lose mass as they age, and understanding mass loss is important for understanding stellar evolution. The initial-final mass relation (IFMR) is the relationship between a white dwarf’s initial mass on the main sequence and its final mass. We have developed a new method for fitting the IFMR based on a Bayesian analysis of photometric observations, combining deterministic models of stellar evolution in an internally coherent way. No mass data are used. Our method yields precise inferences (with uncertainties) for a parameterized linear IFMR. Our method can also return posterior distributions of white dwarf initial and final masses.

Improving White Dwarfs As Chronometers With Gaia Parallaxes And Spectroscopic Metallicities, Adam Moss, Ted Von Hippel, Elliot Robinson, Kareem El-Badry, David C. Stenning, David Van Dyk, Morgan Fouesneau, Coryn A.L. Bailer-Jones, Elizabeth Jeffery, Jimmy Sargent, Isabelle Kloc, Natalie Moticska

Publications

White dwarfs (WDs) offer unrealized potential in solving two problems in astrophysics: stellar age accuracy and precision. WD cooling ages can be inferred from surface temperatures and radii, which can be constrained with precision by high-quality photometry and parallaxes. Accurate and precise Gaia parallaxes along with photometric surveys provide information to derive cooling and total ages for vast numbers of WDs. Here we analyze 1372 WDs found in wide binaries with main-sequence (MS) companions and report on the cooling and total age precision attainable in these WD+MS systems. The total age of a WD can be further constrained if its …

Cepheid Variable Light Curve Analysis On The Embry-Riddle 1-Meter Telescope, Kayla Taylor

Beyond: Undergraduate Research Journal

This report details light curve analysis for four Cepheid variable stars (Polaris, RT Aurigae, RX Aurigae, and Zeta Geminorum) using Embry-Riddle Aeronautical University's 1-meter reflecting telescope and a SBIG-STX 16803 camera with a g filter. Observations were conducted once per week during the Spring 2021 semester; at least one three-hour shift was allotted per week according to the Observational Astronomy Telescope Allocation Committee (TAC). Individual light curves for each target Cepheid were then compared to published data to analyze evidence of evolution on the Instability Strip. Although the light curves showed the sinusoidal nature of brightness oscillations, amplitudes of the …

The M Supergiant High-Mass X-Ray Binary 4u 1954+31, Kenneth H. Hinkle, Thomas Lebzelter, Francis C. Fekel, Oscar Straniero, Richard Joyce, Lisa Prato, Nicole Karnath, Nolan Habel

Information Systems and Engineering Management Research Publications

The X-ray binary 4U 1954+31 has been classified as a low-mass X-ray binary containing an M giant and a neutron star (NS). It has also been included in the rare class of X-ray symbiotic binaries. The Gaia parallax, infrared colors, spectral type, abundances, and orbital properties of the M star demonstrate that the cool star in this system is not a low-mass giant but a high-mass M supergiant. Thus, 4U 1954+31 is a high-mass X-ray binary (HMXB) containing a late-type supergiant. It is the only known binary system of this type. The mass of the M I is ${9}_{-2}^{+6}$ M⊙ …

A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, Matt Wentzel-Long

Dissertations

The W4 HII region is home to a large number of O and B-type stars as well as the young open cluster IC 1805. OB-type produce intense photoionizing radiation and stellar winds that can induce star formation in surrounding molecular clouds and sometimes carve out large regions of decreased particle density called superbubbles. During the star formation process, young stellar objects (YSOs) are initially surrounded by circumstellar disks made of gas and dust which naturally dissipate after several million years. The dissipation of the disk is thought to occur for a variety of reasons, including photoevaporation by the encompassed protostar …

Absolute Dimensions Of The Unevolved F-Type Eclipsing Binary Bt Vulpeculae, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report extensive differential V-band photometry and high-resolution spectroscopy for the 1.14 day, detached, double-lined eclipsing binary BT Vul (F0+F7). Our radial-velocity monitoring and light-curve analysis lead to absolute masses and radii of ${M}_{1}=1.5439\pm 0.0098\,{{ \mathcal M }}_{\odot }^{{\rm{N}}}$ and ${R}_{1}=1.536\pm 0.018\,{{ \mathcal R }}_{\odot }^{{\rm{N}}}$ for the primary, and ${M}_{2}=1.2196\pm 0.0080\,{{ \mathcal M }}_{\odot }^{{\rm{N}}}$ and ${R}_{2}=1.151\pm 0.029\,{{ \mathcal R }}_{\odot }^{{\rm{N}}}$ for the secondary. The effective temperatures are 7270 ± 150 K and 6260 ± 180 K, respectively. Both stars are rapid rotators, and the orbit is circular. A comparison with stellar evolution models from the MESA Isochrones …

Magnetic Structure And Radiative Captures Of Few-Nucleon Systems: Status And Prospects, Laura Elisa Marcucci, Rocco Schiavilla, Alex Gnech, Michele Viviani

Physics Faculty Publications

We review the main ingredients for an ab-initio study of few-nucleon reactions of astrophysical interest within the chiral effective field theory approach, with particular attention to radiative captures relevant for Big Bang Nucleosynthesis and stellar evolution. We conclude with an outlook for ongoing and future work.

Secondary Infall In The Seyfert's Sextet: A Plausible Way Out Of The Short Crossing Time Paradox, Omar López-Cruz, Héctor Javier Ibarra-Medel, Sebastián F. Sánchez, Mark Birkinshaw, Christopher Añorve, Jorge K. Barrera-Ballesteros, Jesús Falcon-Barroso, Wayne A. Barkhouse, Juan P. Torres-Papaqui

Physics Faculty Publications

We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly available data to investigate the star formation histories of galaxies in the Seyfert's Sextet (SS; HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories, we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turnaround, initially gas-rich galaxies crossed for the first time, consuming …

Galactic Open Clusters, Ted Von Hippel

Ted von Hippel

The study of open clusters has a classic feel to it since the subject predates anyone alive today. Despite the age of this topic, I show via an ADS search that its relevance and importance in astronomy has grown faster in the last few decades than astronomy in general. This is surely due to both technical reasons and the interconnection of the field of stellar evolution to many branches of astronomy. In this review, I outline what we know today about open clusters and what they have taught us about a range of topics from stellar evolution to Galactic structure …

Absolute Dimensions Of The Early F-Type Eclipsing Binary V506 Ophiuchi, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report extensive differential V-band photometry and high-resolution spectroscopic observations of the early F-type, 1.06-day detached eclipsing binary V506 Oph. The observations, along with times of minimum light from the literature, are used to derive a very precise ephemeris and the physical properties for the components, with the absolute masses and radii being determined to 0.7% or better. The masses are 1.4153 ± 0.0100 M☉ and 1.4023 ± 0.0094 M☉ for the primary and secondary, the radii are 1.725 ± 0.010 R☉ and 1.692 ± 0.012 R☉, and the effective temperatures are 6840 ± 150 K and 6780 ± 110 …

Infrared Spectroscopy Of Symbiotic Stars. Xii. The Neutron Star Syxb System 4u 1700+24 = V934 Herculis, Kenneth H. Hinkle, Francis C. Fekel, Richard Joyce, Joanna Mikołajewska, Cezary Gałan, Thomas Lebzelter

Information Systems and Engineering Management Research Publications

The X-ray symbiotic (SyXB) V934 Her = 4U 1700+24 is an M giant–neutron star (NS) binary system. Employing optical and infrared radial velocities spanning 29 yr combined with the extensive velocities in the literature, we compute the spectroscopic orbit of the M giant in that system. We determine an orbital period of 4391 days, or 12.0 yr, the longest for any SyXB and far longer than the 404 day orbit commonly cited for this system in the literature. In addition to the 12.0 yr orbital period, we find a shorter period of 420 days, similar to the one previously found. …

The Quadruple-Lined, Doubly Eclipsing System V482 Persei, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Marek Wolf, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report spectroscopic and differential photometric observations of the A-type system V482 Per, which reveal it to be a rare hierarchical quadruple system containing two eclipsing binaries. One binary has the previously known orbital period of 2.4 days and a circular orbit, and the other a period of 6 days, a slightly eccentric orbit (e = 0.11), and shallow eclipses only 2.3% deep. The two binaries revolve around their common center of mass in a highly elongated orbit (e = 0.85) with a period of 16.67 yr. Radial velocities are measured for all components from our quadruple-lined spectra and are …

Absolute Dimensions Of The Metallic-Line Eclipsing Binary V501 Monocerotis, Guillermo Torres, Claud H. Sandberg Lacy, Krešimir Pavlovski, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report extensive high-resolution spectroscopic observations and V-band differential photometry of the slightly eccentric 7.02 day detached eclipsing binary V501 Mon (A6m+F0), which we use to determine its absolute dimensions to high precision (0.3% for the masses and 1.8% for the radii, or better). The absolute masses, radii, and temperatures are MA = 1.6455 ± 0.0043 M⊙, RA = 1.888 ± 0.029 R⊙, and ${T}_{{\rm{eff}}}^{{\rm{A}}}$ = 7510 ± 100 K for the primary and MB = 1.4588 ± 0.0025 M⊙, RB = 1.592 ± 0.028 R⊙, and TeffB = 7000 ± 90 K for the secondary. Apsidal motion has been …

Spectropolarimetry Of Epsilon Aurigae: Probing Stellar And Disk Atmospheres, Kathleen M. Geise

Electronic Theses and Dissertations

The bright eclipsing binary system epsilon Aurigae offers a unique opportunity to uncover physical mechanisms contributing to disk formation and evolution and to explore the relationship between photospheric anisotropies, stellar pulsation and mass loss. This research contributes to our understanding of stellar evolution in the context of binary stars. The research also offers the opportunity to investigate disk formation and evolution significant to our understanding of protoplanetary disks now seen in many star systems. Lastly, the project considers radiative transfer of polarized light that contributes to diverse fields such as atmospheric studies of exoplanets.

My objective is to understand the …

The Stellar-Activity–Rotation Relationship And The Evolution Of Stellar Dynamos, Nicholas J. Wright, Jeremy J. Drake, Eric E. Mamajek, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We present a sample of 824 solar and late-type stars with X-ray luminosities and rotation periods. This is used to study the relationship between rotation and stellar activity and derive a new estimate of the convective turnover time. From an unbiased subset of this sample the power-law slope of the unsaturated regime, LX/Lbol∝Roβ, is fit as β = −2.70 ± 0.13. This is inconsistent with the canonical β = −2 slope to a confidence of 5σ, and argues for an additional term in the dynamo number equation. From a simple scaling analysis this implies ΔΩ/Ω∝Ω0.7, i.e., the differential rotation of …

Stellar Population Models And Individual Element Abundances. I. Sensitivity Of Stellar Evolution Models, Aaron Dotter, Brian Chaboyer, Jason W. Ferguson, Hyun-Chul Lee

Dartmouth Scholarship

Integrated light from distant galaxies is often compared to stellar population models via the equivalent widths of spectral features—spectral indices—whose strengths rely on the abundances of one or more elements. Such comparisons hinge not only on the overall metal abundance, but also on relative abundances. Studies have examined the influence of individual elements on synthetic spectra but little has been done to address similar issues in the stellar evolution models that underlie most stellar population models. Stellar evolution models will primarily be influenced by changes in opacities. In order to explore this issue in detail, 12 sets of stellar evolution …

Development Of An H-Alpha Index For The Detection Of Pms Candidates In Young Open Clusters, Liberty Rae Evanko

Theses and Dissertations

One phase of formation of medium- and low-mass stars is the optically visible phase known as the pre-main-sequence or PMS phase. In order to further the understanding of this phase, more of these PMS objects need to be identified and classified. Previous techniques have used photometry to identify possible PMS objects by their characteristic Hα emission. Once identified these objects can be studied spectroscopically yielding complete PMS classification. This study develops a method to locate these emission objects that overcomes two limitations of previous techniques. The first limitation is the need for the creation of reddening maps. It is eliminated …

From Canonical To Enhanced Extra Mixing In Low‐Mass Red Giants: Tidally Locked Binaries, Pavel A. Denissenkov, Brian Chaboyer, Ke Li

Dartmouth Scholarship

Stellar models that incorporate simple diffusion or shear-induced mixing are used to describe canonical extra mixing in low-mass red giants of low and solar metallicity. These models are able to simultaneously explain the observed Li and CN abundance changes along the upper red giant branch (RGB) in field low-metallicity stars and match photometry, rotation, and ¹²C/¹³C ratios for stars in the old open cluster M67. The shear mixing model requires that main-sequence (MS) progenitors of upper RGB stars possessed rapidly rotating radiative cores and that specific angular momentum was conserved in each of their mass shells during …

Theoretical Uncertainties In Red Giant Branch Evolution: The Red Giant Branch Bump, Stephan R. R. Bjork, Brian Chaboyer

Dartmouth Scholarship

A Monte Carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal-poor globular clusters has been conducted. Confidence limits are derived on the absolute V-band magnitude of the bump in the red giant branch luminosity function (M_V,b) and the excess number of stars in the bump, R_b. The analysis takes into account uncertainties in the primordial helium abundance, abundance of α-capture elements, radiative and conductive opacities, nuclear reaction rates, neutrino energy losses, the treatments of diffusion and convection, the surface boundary conditions, and color transformations. The uncertainty in …

Galactic Open Clusters, Ted Von Hippel

Publications

The study of open clusters has a classic feel to it since the subject predates anyone alive today. Despite the age of this topic, I show via an ADS search that its relevance and importance in astronomy has grown faster in the last few decades than astronomy in general. This is surely due to both technical reasons and the interconnection of the field of stellar evolution to many branches of astronomy. In this review, I outline what we know today about open clusters and what they have taught us about a range of topics from stellar evolution to Galactic structure …

Long Period Variables In The Globular Cluster 47 Tuc: Radial Velocity Variations, Thomas Lebzelter, Peter R. Wood, Kenneth H. Hinkle, Richard R. Joyce, Francis C. Fekel

Information Systems and Engineering Management Research Publications

We present near infrared velocity curves for 12 long period variables (LPVs) in the globular cluster 47 Tuc (NGC 104). New light curves are also presented for these variables. Results are compared with the period-luminosity sequences occupied by the LPVs in the LMC. Sequence C variables (fundamental mode pulsators) have larger velocity amplitudes than sequence B variables (first overtone pulsators). We show that, at similar luminosities, higher mass loss rates are associated with larger pulsation amplitudes. One variable (V18) does not fit the normal period luminosity sequences and it has an unusually large amount of circumstellar dust, suggesting that it …

A Study Of Bright Southern Long Period Variables, Thomas Lebzelter, Kenneth H. Hinkle, Peter R. Wood, Richard R. Joyce, Francis C. Fekel

Information Systems and Engineering Management Research Publications

In this paper we present radial velocity curves of AGB variables that exhibit various kinds of anomalies: semiregular variables (SRVs) with typical mira periods, SRVs exceeding the mira 2.5 mag amplitude limit, miras with secondary maxima in their light curves, and a SRV with a long secondary period. The stars with reliable Hipparcos parallaxes from this and from previous studies are plotted in a -diagram. Our objects nicely follow the -relations determined for the LMC. This allows the pulsation mode to be identified. While all miras fall on the fundamental mode sequence, the SRVs fall on both the first overtone …

White Dwarfs In Open Clusters: New Tests Of Stellar Evolution And The Age Of The Galaxy, Ted Von Hippel

Publications

White dwarf cooling theory and very deep observations in star clusters provide a new tool to test stellar evolution theory and time scales. In particular, white dwarf cooling theory is now testing the degree of enhanced core mixing in stars with turnoff ages of 1 to 2 Gyr. More generally, I show the good overall agreement between white dwarf and modern isochrone ages over the range 0.1 to 4 Gyr.

Spectroscopy And Photometry Of Nearby Young Solar Analogs, Eric J. Gaidos, Gregory W. Henry, Stephen M. Henry

Information Systems and Engineering Management Research Publications

We present new photometry and spectroscopy of 34 stars from a catalog of 38 nearby (d < 25 pc) G and K dwarfs selected as analogs to the early Sun. We report that the least active star in our sample is also slowly rotating and probably of solar age. Two other stars appear to be evolved objects that have recently acquired angular momentum. A fourth star may be a spectroscopic binary. Many of the other stars belong to previously identified common proper-motion groups. Space motions, lithium abundances, and Ca II emission of these stars suggest ages between 70 and 800 Myr.

Chromospherically Active Stars. Xvi. The Double-Lined Binary 42 Capricorni, Francis C. Fekel

Information Systems and Engineering Management Research Publications

New spectroscopic observations of the chromospherically active binary, 42 Capricorni, have resulted in the detection of lines of the secondary, improved orbital elements, and the determination of fundamental properties of the components. 42 Cap has an orbital period of 13.174004 d, an eccentricity of 0.176, and a mass ratio A/B of 1.375. No evidence for a variation of the center-of-mass velocity, suggested by earlier investigators, has been found. Spectral types of the primary and secondary are G1 IV and G2 V, respectively. The V mag difference of 1.94 and HIPPARCOS parallax result in MV = 2.79 mag for A and …

The Extremely Active Single Giant 1e 1751+7046 = Et Draconis: Revised Properties And A Reevaluation Of Its Evolutionary Status, Carol W. Ambruster, Francis C. Fekel, Edward F. Guinan, Bruce J. Hrivnak

Information Systems and Engineering Management Research Publications

New spectroscopic observations have resulted in significant revisions to several of the orginally published properties of the X-ray bright, chromospherically active star 1E 1751+7046: the spectral classification has been revised from K5 IV to K0 III, v sin i from 30-40 km s-1 to 23 km s-1, and the reported nondetection of the Li I 6707 Å line to a significant log epsilon(Li) = 1.8. Chromospheric and transition region surface fluxes from IUE observations and the coronal surface flux from earlier Einstein data are close to saturation levels, and comparable only to very active binaries, pre-main-sequence stars, and FK Comae …

The Spectroscopic-Speckle Triple System Hr 6469, Colin D. Scarfe, David J. Barlow, Francis C. Fekel, Richard F. Rees, R. W. Lyons, Charles Thomas Bolton, Harold A. Mcalister, William I. Hartkopf

Information Systems and Engineering Management Research Publications

HR 6469 consists of an evolved G star and a close pair of stars, believed to be on the main sequence, the brighter of which is an early F star. Shallow eclipses have been detected in the close pair and the components of the wide system have been resolved over most of the orbit by speckle interferometry (McAlister & Hartkopf, Second Catalog of Interferometric Observations of Binary Stars, Center for High Angular Resolution Astronomy, Contribution No. 2 (CHARA), 1988). This paper presents radial velocities, obtained at the David Dunlap, McDonald, Kitt Peak and Dominion Astrophysical Observatories, for the G star …

Chromospherically Active Stars. Viii. Hd 155683 = V972 Herculis: Observational Constraints On Evolutionary Theory, Francis C. Fekel

Information Systems and Engineering Management Research Publications

V792 Her is an eclipsing RS CVn binary with an orbital period of 27.54 days whose components have spectral types of K0 III and F2 IV. New spectroscopic observations combined with existing photometry have resulted in masses of 1.47 + or - 0.003 solar mass and 1.41 + or - 0.003 solar mass for the K giant and F star, respectively. Additional fundamental parameters are derived. Standard evolutionary models were specifically computed by VandenBerg (1990) for the two stars. The best fit occurs if the components are somewhat metal poor with Fe/H/ = - 0.46. Ages of about 2.3 x …

Evolution Of The Starspots In V478 Lyrae From 1980 To 1988, Douglas S. Hall, Gregory W. Henry, James R. Sowell

Information Systems and Engineering Management Research Publications

Differential UBV photometry of V478 Lyrae from 1980 to 1988 is given and analyzed as 22 separate light curves, each spanning an average of a dozen rotation cycles. It is shown that spots on V478 Lyr appear to have lifetimes on the order of several months to a year. The amplitude of the light loss produced by a spot can change by a factor of 2 within 20 days. In the only four determinate cases, a spot came into existence at one of the two conjunctions, that is, in the middle of the hemisphere facing (or opposing) the companion star. …