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Full-Text Articles in Physical Sciences and Mathematics
Search For Gravitational Waves From Scorpius X-1 With A Hidden Markov Model In O3 Ligo Data, R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari, M. G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang
Search For Gravitational Waves From Scorpius X-1 With A Hidden Markov Model In O3 Ligo Data, R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari, M. G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang
Physics and Astronomy Faculty Publications and Presentations
Results are presented for a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to allow for spin wandering. This search improves on previous HMM-based searches of Laser Interferometer Gravitational-Wave Observatory data by including the orbital period in the search template grid, and by analyzing data from the latest (third) observing run. In the frequency range searched, from 60 to 500 Hz, we find no evidence of gravitational radiation. This is the most sensitive search for Scorpius X-1 using a HMM to date. For the most sensitive subband, starting at …
A Monte Carlo Method For Evaluating Empirical Gyrochronology Models And Its Application To Wide Binary Benchmarks, Tomomi Otani, Ted Von Hippel, Derek Buzasi, Terry Oswalt, Alexander Stone-Martinez, Patrice Majewski
A Monte Carlo Method For Evaluating Empirical Gyrochronology Models And Its Application To Wide Binary Benchmarks, Tomomi Otani, Ted Von Hippel, Derek Buzasi, Terry Oswalt, Alexander Stone-Martinez, Patrice Majewski
Publications
No abstract provided.
Establishing Α Oph As A Prototype Rotator: Precision Orbit With New Keck, Chara, And Rv Observations, Tyler Gardner, John D. Monnier, Francis C. Fekel, Michael H. Williamson, Fabien Baron, Sasha Hinkley, Michael Ireland, Adam L. Kraus, Stefan Kraus, Rachael M. Roettenbacher, Gail Schaefer, Judit Sturmann, Laszlo Sturmann, Theo A. Ten Brummelaar
Establishing Α Oph As A Prototype Rotator: Precision Orbit With New Keck, Chara, And Rv Observations, Tyler Gardner, John D. Monnier, Francis C. Fekel, Michael H. Williamson, Fabien Baron, Sasha Hinkley, Michael Ireland, Adam L. Kraus, Stefan Kraus, Rachael M. Roettenbacher, Gail Schaefer, Judit Sturmann, Laszlo Sturmann, Theo A. Ten Brummelaar
Information Systems and Engineering Management Research Publications
Alpha Ophiuchi (Rasalhague) is a nearby rapidly rotating A5IV star that has been imaged by infrared interferometry. α Oph is also part of a known binary system, with a companion semimajor axis of ∼430 mas and a high eccentricity of 0.92. The binary companion provides the unique opportunity to measure the dynamical mass to compare with the results of rapid rotator evolution models. The lack of data near periastron passage limited the precision of mass measurements in previous work. We add new interferometric data from the MIRC combiner at the CHARA Array as well as new Keck adaptive optics imaging …
Speckle Imaging Characterization Of Radial Velocity Exoplanet Systems, Paul A. Dalba, Stephen R. Kane, Steve B. Howell, Elliott P. Horch, Zhexing Li, Lea A. Hirsch, Jennifer Burt, Timothy D. Brandt, Teo Močnik, Gregory W. Henry, Mark E. Everett, Lee J. Rosenthal, Andrew W. Howard
Speckle Imaging Characterization Of Radial Velocity Exoplanet Systems, Paul A. Dalba, Stephen R. Kane, Steve B. Howell, Elliott P. Horch, Zhexing Li, Lea A. Hirsch, Jennifer Burt, Timothy D. Brandt, Teo Močnik, Gregory W. Henry, Mark E. Everett, Lee J. Rosenthal, Andrew W. Howard
Information Systems and Engineering Management Research Publications
We conducted speckle imaging observations of 53 stellar systems that were members of long-term radial velocity (RV) monitoring campaigns and exhibited substantial accelerations indicative of planetary or stellar companions in wide orbits. Our observations were made with blue and red filters using the Differential Speckle Survey Instrument at Gemini-South and the NN-Explore Exoplanet Stellar Speckle Imager at the WIYN telescope. The speckle imaging identifies eight luminous companions within 2'' of the primary stars. In three of these systems—HD 1388, HD 87359, and HD 104304—the properties of the imaged companion are consistent with the RV measurements, suggesting that these companions may …
Bayesian Characterization Of Main-Sequence Binaries In The Old Open Cluster Ngc 188, Roger E. Cohen, Ted Von Hippel, Aaron M. Geller
Bayesian Characterization Of Main-Sequence Binaries In The Old Open Cluster Ngc 188, Roger E. Cohen, Ted Von Hippel, Aaron M. Geller
Publications
The binary fractions of open and globular clusters yield powerful constraints on their dynamical state and evolutionary history. We apply publicly available Bayesian analysis tools to a UBV RIJHKS photometric catalog of the open cluster NGC 188 to detect and characterize photometric binaries along the cluster main sequence. This technique has the advantage of self-consistently handling photometric errors, missing data in various bandpasses, and star-by-star prior constraints on cluster membership. Simulations are used to verify uncertainties and quantify selection biases in our analysis, illustrating that among binaries with mass ratios >0.5, we recover the binary fraction to better than …
Young Blue Straggler Stars In The Galactic Field, Gemunu Ekanayake, Ronald Wilhelm
Young Blue Straggler Stars In The Galactic Field, Gemunu Ekanayake, Ronald Wilhelm
Physics and Astronomy Faculty Publications
In this study, we present an analysis of a sample of field blue straggler (BS) stars that show high ultra violet emission in their spectral energy distributions (SEDs): indication of a hot white dwarf (WD) companion to BS. Using photometry available in the Sloan Digital Sky Survey (SDSS) and Galaxy Evolution Explorer (GALEX) surveys, we identified 80 stars with ultraviolet (UV) excess. To determine the parameter distributions (mass, temperature, and age) of the WD companions, we developed a fitting routine that could fit binary model SEDs to the observed SED. Results from this fit indicate the need for a hot …
On The Progenitors Of Type Ia Supernovae, Mario Livio, Paolo Mazzali
On The Progenitors Of Type Ia Supernovae, Mario Livio, Paolo Mazzali
Physics & Astronomy Faculty Research
We review all the models proposed for the progenitor systems of Type Ia supernovae and discuss the strengths and weaknesses of each scenario when confronted with observations. We show that all scenarios encounter at least a few serious difficulties, if taken to represent a comprehensive model for the progenitors of all Type Ia supernovae (SNe Ia). Consequently, we tentatively conclude that there is probably more than one channel leading SNe Ia. While the single-degenerate scenario (in which a single white dwarf accretes mass from a normal stellar companion) has been studied in some detail, the other scenarios will need a …
Search For Binaries In The Kepler K2 Fields Using Pulsation Timing Method, Tomomi Otani, Terry Oswalt
Search For Binaries In The Kepler K2 Fields Using Pulsation Timing Method, Tomomi Otani, Terry Oswalt
Publications
Finding orbital solutions of binaries which have small mass ratios (50 days) is challenging using traditional techniques. The radial velocity method is a good way to detect such binary stars, however it requires large telescopes. Therefore, the search for binaries in those regions is still incomplete. For binaries in this regime with at least one component that pulsates, pulsation timing is a better approach. Orbital solutions for such systems can be obtained from the periodic change in pulse arrival times as the star’s reflex motion is manifested by the changing distance along the line of sight. We present a search …
Gyrochronology Of Wide Binaries In The Kepler K2 Campaign 5 Field, Terry D. Oswalt, Derek Buzasi, Tomomi Otani
Gyrochronology Of Wide Binaries In The Kepler K2 Campaign 5 Field, Terry D. Oswalt, Derek Buzasi, Tomomi Otani
Publications
We are determining rotation periods for an ensemble of over 100 wide non-interacting binary stars in the K2 Campaign 5 field that contain two main sequence dwarfs, as well as a smaller sample containing at least one white dwarf component. Observations of such coeval pairs provide the basis for our new investigation of rotation-based age determinations. Such “gyrochronology” ages can achieve a precision that exceeds most other current method of stellar age determination. Here we present a status report on our analysis of the light curves extracted from the K2 Campaign 5 field.
Optical Studies Of 13 Hard X-Ray Selected Cataclysmic Binaries From The Swift-Bat Survey, Jules P. Halpern, John R. Thorstensen
Optical Studies Of 13 Hard X-Ray Selected Cataclysmic Binaries From The Swift-Bat Survey, Jules P. Halpern, John R. Thorstensen
Dartmouth Scholarship
From a set of 13 cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of 11, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ranging from 81 minutes to 20.4 hr. PBC J0706.7+0327 is an AM Herculis star (polar) based on its emission-line variations and large amplitude photometric modulation on the same period. Swift J2341.0+7645 may be a polar, although the evidence here is less …
Optical And X-Ray Studies Of 10 X-Ray-Selected Cataclysmic Binaries, John R. Thorstensen, Jules Halpern
Optical And X-Ray Studies Of 10 X-Ray-Selected Cataclysmic Binaries, John R. Thorstensen, Jules Halpern
Dartmouth Scholarship
We report on ground-based optical observations of 10 cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 minutes to 9.38 hr. We also obtained time-series optical photometry for six targets, four of which have coherent pulsations. These periods are 1218 s for 1RXS J045707.4+452751, 628 s for AX J1740.2–2903, 477 s for AX J1853.3–0128, and 935 s for IGR J19267+1325. A total of seven of the sources have coherent oscillations in X-rays or optical, indicating that …
The Interior Structure Constants As An Age Diagnostic For Low-Mass, Pre-Main-Sequence Detached Eclipsing Binary Stars, Gregory A. Feiden, Aaron Dotter
The Interior Structure Constants As An Age Diagnostic For Low-Mass, Pre-Main-Sequence Detached Eclipsing Binary Stars, Gregory A. Feiden, Aaron Dotter
Dartmouth Scholarship
We propose a novel method for determining the ages of low-mass, pre-main-sequence stellar systems using the apsidal motion of low-mass detached eclipsing binaries. The apsidal motion of a binary system with an eccentric orbit provides information regarding the interior structure constants of the individual stars. These constants are related to the normalized stellar interior density distribution and can be extracted from the predictions of stellar evolution models. We demonstrate that low-mass, pre-main-sequence stars undergoing radiative core contraction display rapidly changing interior structure constants (greater than 5% per 10 Myr) that, when combined with observational determinations of the interior structure constants …
Self-Consistent Magnetic Stellar Evolution Models Of The Detached, Solar-Type Eclipsing Binary Ef Aquarii, Gregory A. Feiden, Brian Chaboyer
Self-Consistent Magnetic Stellar Evolution Models Of The Detached, Solar-Type Eclipsing Binary Ef Aquarii, Gregory A. Feiden, Brian Chaboyer
Dartmouth Scholarship
We introduce a new one-dimensional stellar evolution code, based on the existing Dartmouth code, that self-consistently accounts for the presence of a globally pervasive magnetic field. The methods involved in perturbing the equations of stellar structure, the equation of state, and the mixing-length theory of convection are presented and discussed. As a first test of the code's viability, stellar evolution models are computed for the components of a solar-type, detached eclipsing binary (DEB) system, EF Aquarii, shown to exhibit large disagreements with stellar models. The addition of the magnetic perturbation corrects the radius and effective temperature discrepancies observed in EF …
Reevaluating The Mass-Radius Relation For Low-Mass, Main-Sequence Stars, Gregory A. Feiden, Brian Chaboyer
Reevaluating The Mass-Radius Relation For Low-Mass, Main-Sequence Stars, Gregory A. Feiden, Brian Chaboyer
Dartmouth Scholarship
We examine the agreement between the observed and theoretical low-mass (<0.8 M ☉) stellar main-sequence mass-radius relationship by comparing detached eclipsing binary (DEB) data with a new, large grid of stellar evolution models. The new grid allows for a realistic variation in the age and metallicity of the DEB population, characteristic of the local galactic neighborhood. Overall, our models do a reasonable job of reproducing the observational data. A large majority of the models match the observed stellar radii to within 4%, with a mean absolute error of 2.3%. These results represent a factor of two improvement compared to …
Spectroscopy Of Early F Stars: Γ Doradus Candidates And Possible Metallic Shell Stars, Francis C. Fekel, Phillip B. Warner, Anthony B. Kaye
Spectroscopy Of Early F Stars: Γ Doradus Candidates And Possible Metallic Shell Stars, Francis C. Fekel, Phillip B. Warner, Anthony B. Kaye
Information Systems and Engineering Management Research Publications
We obtained high-resolution spectroscopic observations of 34 γ Doradus candidates. From the red-wavelength spectra, we determined spectral classes, radial velocities, and projected rotational velocities. The spectra of seven late A or early F stars show metallic lines that have composite profiles consisting of a narrow component near the center of a broad line, indicating that they may be shell stars or binaries. Several stars, including HD 152896, HD 173977, HD 175337, and HD 195068/9, show large line profile asymmetries. Two stars, HD 11443 (=α Trianguli) and HD 149420, are ellipsoidal variables and not γ Doradus stars. The percentage of binary …
Lisa, Binary Stars, And The Mass Of The Graviton, Curt Cutler, William A. Hiscock, Shane L. Larson
Lisa, Binary Stars, And The Mass Of The Graviton, Curt Cutler, William A. Hiscock, Shane L. Larson
All Physics Faculty Publications
We extend and improve earlier estimates of the ability of the proposed LISA (Laser Interferometer Space Antenna) gravitational wave detector to place upper bounds on the graviton mass mg by comparing the arrival times of gravitational and electromagnetic signals from binary star systems. We show that the best possible limit on mg obtainable this way is ∼50 times better than the current limit set by solar system measurements. Among currently known, well-understood binaries, 4U1820-30 is the best for this purpose; LISA observations of 4U1820-30 should yield a limit ≈3-4 times better than the present solar system bound. AM …
A Photometric And Spectroscopic Study Of The Cataclysmic Variable Sx Leonis Minoris In Quiescence And Superoutburst, R. Mark Wagner, John R. Thorstensen, R. K. Honeycutt, S. B. Howell
A Photometric And Spectroscopic Study Of The Cataclysmic Variable Sx Leonis Minoris In Quiescence And Superoutburst, R. Mark Wagner, John R. Thorstensen, R. K. Honeycutt, S. B. Howell
Dartmouth Scholarship
We present CCD imaging, CCD photometry on long and short timescales, and time-resolved spectroscopy of SX LMi, a new SU Ursae Majoris type dwarf nova. The quiescent optical spectrum shows broad double-peaked Balmer, He I, and He II emission lines, similar to other quiescent dwarf novae. Absorption lines from a late-type secondary are not detected. Time-resolved spectra obtained in quiescence reveal radial velocity variations of the Balmer emission lines on a period of 0.06717 ± 0.00011 days, or 96.72 ± 0.16 minutes, with only a slight possibility of a daily cycle-count error. Optical photometry obtained between 1987 and 1991 shows …
Chromospherically Active Stars. Xiii. Hd 30957: A Double Lined K Dwarf Binary, Francis C. Fekel, Virgiljus Dadonas, Julius Sperauskas, Todd R. Vaccaro, L. Ronald Patterson
Chromospherically Active Stars. Xiii. Hd 30957: A Double Lined K Dwarf Binary, Francis C. Fekel, Virgiljus Dadonas, Julius Sperauskas, Todd R. Vaccaro, L. Ronald Patterson
Information Systems and Engineering Management Research Publications
HD 30957 is a double-lined spectroscopic binary with a period of 44.395 days and a modest eccentricity of 0.09. The spectral types of the components are K2-3 V and K5 V. The measured v sin i for both components is less than or equal to 3 km/s and the orbital inclination is estimated to be 69 deg. The system is relatively nearby with a parallax of 0.025 sec or a distance of 40 pc. Space motions of the system indicate that it does not belong to any of the known moving groups. Absolute surface fluxes of the Ca II H …
Extremely Active Long-Period Rs Cvn Binary Hd 12545, Bernard W. Bopp, Francis C. Fekel, Jason P. Aufdenberg, Robert C. Dempsey, Virgiljus Dadonas
Extremely Active Long-Period Rs Cvn Binary Hd 12545, Bernard W. Bopp, Francis C. Fekel, Jason P. Aufdenberg, Robert C. Dempsey, Virgiljus Dadonas
Information Systems and Engineering Management Research Publications
The active-chromosphere giant HD 12545 is noteworthy for its remarkable 1990 photmetric amplitude of 0.6 mag in V, which implies that nearly half the visible hemisphere of the star was covered by cool spots. We report the results of a spectroscopic study of HD 12545, showing it to be an active-chromosphere binary with an orbital period of 23.97 days. We establish the spectral type as KO III, and measure v sin i = 17 +/- 2 km/s. The various indicators of activity in the optical and ultraviolet suggest that HD 12545 is one of the most active RS CVn systems …
The Spectroscopic Orbit Of Gamma Geminorum And A Search For Its Secondary, Francis C. Fekel, Jocelyn Tomkin
The Spectroscopic Orbit Of Gamma Geminorum And A Search For Its Secondary, Francis C. Fekel, Jocelyn Tomkin
Information Systems and Engineering Management Research Publications
New spectroscopic observations of Gamma Geminorum, a bright, 'normal' A1 IV star have resulted in an improved spectroscopic orbit. The orbital period is 12.632 +/- 0.002 yr, the eccentricity is 0.893 +/-0.002, and the orbital parallax is 0.0291 +/-0.0024 arcsec, or a distance of 34 pc. We determine a v sin i of 8 +/-1 km/s for the A star, which confirms that it is a slow rotator. Near-infrared spectroscopic observations at 8806 A, obtained through the brief nodal passage, have resulted in the probable detection of the secondary. The masses are 2.8 and 1.07 solar mass and the Delta …
Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall
Chromospherically Active Stars. X. Spectroscopy And Photometry Of Hd 212280, Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton, Douglas S. Hall
Information Systems and Engineering Management Research Publications
The system HD 212280 is a chromospherically active double lined spectroscopic binary with an orbital period of 45.284 days and an eccentricity of 0.50. The spectrum is composite with spectral types of G8 IV and F5-8 V for the components. An estimated inclination of 78 +/- 8 deg results in masses of 1.7 and 1.4 solar mass for the G subgiant and mid-F star, respectively. The distance to the system is estimated to be 112 pc. Photometric observations obtained between 1987 November and 1992 June reveal that HD 212280 is a newly identified variable star with a V amplitude of …
Observations Of The Ca Ii Infrared Triplet In Chromospherically Active Single And Binary Stars, Robert C. Dempsey, Bernard W. Bopp, Gregory W. Henry, Douglas S. Hall
Observations Of The Ca Ii Infrared Triplet In Chromospherically Active Single And Binary Stars, Robert C. Dempsey, Bernard W. Bopp, Gregory W. Henry, Douglas S. Hall
Information Systems and Engineering Management Research Publications
Spectroscopic observations of the Ca II infrared triplet (8498, 8542, 8662 A) have been obtained for 45 stars which are known or suspected to be chromospherically active. The sample includes both single and binary stars of spectral types from F2 to M5 spanning luminosity classes III, IV, and V. Several different types of activity diagnostics were measured, and their relative merits are discussed. Dependence of chromospheric emission upon rotation period, luminosity, temperature, and duplicity are analyzed. Synchronous binaries show a slight trend of increased emission with decreasing period while the asynchronous binaries show abnormally high activity levels for their rotation …
Extended Variability Of The Symbiotic Star Ag Draconis, Menas Kafatos, S. R. Meier
Extended Variability Of The Symbiotic Star Ag Draconis, Menas Kafatos, S. R. Meier
Mathematics, Physics, and Computer Science Faculty Articles and Research
We have analyzed the complete set of available IUE (International Ultraviolet Explorer) spectra for the symbiotic star AG Draconis covering the period from 1979 to 1989. All absolute line fluxes and wavelengths have been obtained for the prominent emission lines in the λλ1200-3200 wavelength range. These spectra contain observations which were taken before, during and after the two extended outbursts which occurred on 1980 November to 1981 November and 1985 February to 1986 January. These two outburst events have two maxima that are separated by ~1600 days, a time scale not known to be associated with the star, but which …
Hr 266=Ads 784: An Early Type Spectroscopic, Speckle Astrometric Multiple System, Warren A. Cole, Francis C. Fekel, William I. Hartkopf, Harold A. Mcalister, Jocelyn Tomkin
Hr 266=Ads 784: An Early Type Spectroscopic, Speckle Astrometric Multiple System, Warren A. Cole, Francis C. Fekel, William I. Hartkopf, Harold A. Mcalister, Jocelyn Tomkin
Information Systems and Engineering Management Research Publications
The detection and nature of a 'speckle astrometric' system are reported with attention given to alternative interpretations of the system components. The HR 226 = ADS 784 system is described as a short-period binary (with a period of 4.241148 +/- 0.000008 d) orbiting an unseen companion (with a period of 1769 +/- 10 d), and the triple's visual orbit is 83.10 +/- 0.20 yr. The elements of the various orbits taken from spectroscopic data are employed to develop the model scenarios. The masses and spectral types of the components are developed and used to calculate the inclinations of the short-, …
The Extraordinary 1989 December 14/15 Optical Flare Events On V711 Tauri, Gregory W. Henry, Douglas S. Hall
The Extraordinary 1989 December 14/15 Optical Flare Events On V711 Tauri, Gregory W. Henry, Douglas S. Hall
Information Systems and Engineering Management Research Publications
Photometry in B and V taken with the Vanderbilt Tennessee State 16 inch (41 cm) robotic telescope confirms the intense broad-band optical continuum flare activity reported by Chinese observers on the active chromosphere binary V711 Tau on December 14/15, 1989. Twelve hours after the flare reported from China, there occurred a separate and more intense flare with B and V amplitudes of 0.69 and 0.42 mag, respectively. These amplitudes correspond to peak flare luminosities of approximately 2 x 10 to the 33rd ergs/s in B and 1 x 10 to the 33rd ergs/s in V. The observed color of its …
Chromospheric Ca Ii H And K And H Alpha Emission In Single And Binary Stars Of Spectra Types F6--M2, Klaus G. Strassmeier, Francis C. Fekel, Bernard W. Bopp, Robert C. Dempsey, Gregory W. Henry
Chromospheric Ca Ii H And K And H Alpha Emission In Single And Binary Stars Of Spectra Types F6--M2, Klaus G. Strassmeier, Francis C. Fekel, Bernard W. Bopp, Robert C. Dempsey, Gregory W. Henry
Information Systems and Engineering Management Research Publications
New observations of the Ca II H and K and H-epsilon region and/or the Balmer H-alpha line are presented for 100 mostly very active stars but also for weak or inactive stars with suspected activity. Correlations between chromospheric activity at Ca II H and K and H-alpha and effective surface temperature and rotation are identified, and several new stars with chromospheric Ca II H and K emission are discovered. No single activity-rotation relation can be derived for all luminosity classes, and there is clear evidence that evolved stars are generally more active than main-sequence stars of the same rotation period. …
Chromospherically Active Stars. Vii. 39 Ceti=Ay Ceti, Hd185151=V1764 Cygni, And Binary Synchronization, Francis C. Fekel, Joseph J. Eitter
Chromospherically Active Stars. Vii. 39 Ceti=Ay Ceti, Hd185151=V1764 Cygni, And Binary Synchronization, Francis C. Fekel, Joseph J. Eitter
Information Systems and Engineering Management Research Publications
Improved orbital elements have been determined for 39 Ceti and HD 185151.39 Cet has a circular orbit with an orbital period of 56.82 days, which differs substantially from its rotational period of 75-78 days. An observation of the lithium region of 39 Cet shows that the G5 III component has almost no lithium in its outer atmosphere. HD 185151 has a circular orbit with an orbital period of 40.142 days and has a nearly identical rotational period. The large mass function suggests that the secondary is a late A to mid F type star whose continuum should be visible at …
Chromospherically Active Stars. Vi. Hd 136901 = Uv Crb: A Massive Ellipsoidal K Giant Single-Lined Spectroscopic Binary, Francis C. Fekel, J. Davy Kirkpatrick, Xinxing Yang, Klaus G. Strassmeier
Chromospherically Active Stars. Vi. Hd 136901 = Uv Crb: A Massive Ellipsoidal K Giant Single-Lined Spectroscopic Binary, Francis C. Fekel, J. Davy Kirkpatrick, Xinxing Yang, Klaus G. Strassmeier
Information Systems and Engineering Management Research Publications
The variable star HD 136901 = UV CrB is a chromospherically active K2 III single-lined spectroscopic binary with an orbital period of 18.665 days. It has modest-strength Ca H and K emission and UV features, while H-alpha is a strong absorption feature containing little or no emission. The inclination of the system is 53 + or - 12 deg. The v sin i of the primary is 42 + or - 2 km/s, resulting in a minimum radius of 15.5 + or - 0.8 solar. When compared with the Roche lobe radius, this results in a mass ratio of 2.90 …
Rx Puppis: Detection Of Asymmetrical Radio Structure, J. M. Hollis, F. Yusef-Zadeh, T. J. Cornwell, R. J. Oliverson, A. G. Michalitsianos, Menas Kafatos
Rx Puppis: Detection Of Asymmetrical Radio Structure, J. M. Hollis, F. Yusef-Zadeh, T. J. Cornwell, R. J. Oliverson, A. G. Michalitsianos, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
Subarcsecond ( ~0':3 x ~0':1) observations of the RX Puppis symbiotic system with the Very Large Array (VLA) have resolved 2 cm continuum emission which deviates from a previously reported circularly symmetric radio distribution. The radio structure is comprised of at least three nearly colinear components. Under the assumption that the strongest feature is coincident with the hot star, the other two features lie 230 and 590 AU distant. These radio features are reminiscent of small-scale radio structure detected toward R Aquarii, another symbiotic star system, and probably represents material ejected from the RX Puppis system at an earlier epoch.
Chromospherically Active Stars. V. Hd 91816=Lr Hya: A Double-Lined By Draconis Type Binary, Francis C. Fekel, Kim Gillies, John L. Africano, Robert Quigley
Chromospherically Active Stars. V. Hd 91816=Lr Hya: A Double-Lined By Draconis Type Binary, Francis C. Fekel, Kim Gillies, John L. Africano, Robert Quigley
Information Systems and Engineering Management Research Publications
Observations of HD 91816=LR Hya obtained between 1982 and 1988 show it to consist of two nearly identical K0 dwarfs and to have an orbital period of 6.866 days and an orbital eccentricity of 0.014 + or - 0.003. The results suggest that the system has an age equal to or greater than that of the Hyades cluster. A spectroscopic parallax of 0.027 is obtained, and individual minimum masses of 0.55 solar masses each are found, implying an inclination of 61 + or - 3 deg.