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Full-Text Articles in Physical Sciences and Mathematics
Chromospherically Active Stars. Xvi. The Double-Lined Binary 42 Capricorni, Francis C. Fekel
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 …
Whole Earth Telescope Observations Of The Helium Interacting Binary Pg 1346+082 (Cr Bootis), Judith L. Provencal, Donald E. Winget, R. Edward Nather, Edward L. Robinson, J. Christopher Clemens, Paul A. Bradley, Charles F. Claver, Scot J. Kleinman, Albert D. Grauer, Butler P. Hine, Lilia Ferrario, Darragh O'Donoghue, Brian Warner, Gerard Vauclair, Michel Chevreton, Kepler De Souza Oliveira Filho, Matt A. Wood, Gregory W. Henry
Whole Earth Telescope Observations Of The Helium Interacting Binary Pg 1346+082 (Cr Bootis), Judith L. Provencal, Donald E. Winget, R. Edward Nather, Edward L. Robinson, J. Christopher Clemens, Paul A. Bradley, Charles F. Claver, Scot J. Kleinman, Albert D. Grauer, Butler P. Hine, Lilia Ferrario, Darragh O'Donoghue, Brian Warner, Gerard Vauclair, Michel Chevreton, Kepler De Souza Oliveira Filho, Matt A. Wood, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We present our analysis of 240 hr of white-light, high-speed photometry of the dwarf nova-like helium variable PG 1346+082 (CR Boo). We identify two frequencies in the low-state power spectrum, at 679.670 ± 0.004 μHz and 669.887 ± 0.008 μHz. The 679.670 μHz variation is coherent over at least a 2 week time span, the first demonstration of a phase-coherent photometric variation in any dwarf nova-like interacting binary white dwarf system. The high-state power spectrum contains a complex fundamental with a frequency similar, but not identical, to the low-state spectrum, and a series of harmonics not detected in low state. …
Time-Series Photometric Spot Modeling. Iii. Thirty Years In The Life Of Hk Lacertae., Katalin Oláh, Zsolt Kővári, János Bartus, Klaus G. Strassmeier, Douglas S. Hall, Gregory W. Henry
Time-Series Photometric Spot Modeling. Iii. Thirty Years In The Life Of Hk Lacertae., Katalin Oláh, Zsolt Kővári, János Bartus, Klaus G. Strassmeier, Douglas S. Hall, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We present a spot modeling analysis of the active late-type giant HK Lac using 30 years of photometry, including 600 new data points from the last six years. We have analyzed folded light curves and, when we had long continuous data sets, applied a new computer code for time-series modeling. The validity of the modeling results was tested as a function of the photometric noise. We have determined the unspotted brightness of HK Lac in the BV(RI)_C_ bandpasses and obtained a spot temperature of {DELTA}T=1200+/-100K. Polar active regions were recovered throughout the modeling because no other scenario was able to …
Rotational Velocities Of Late-Type Stars, Francis C. Fekel
Rotational Velocities Of Late-Type Stars, Francis C. Fekel
Information Systems and Engineering Management Research Publications
A calibration based on the results of Gray has been used to determine projected rotational velocities for 133 bright stars with spectral types of F, G, or K, most of which appear in {The Bright Star Catalogue}. The vast majority have {v} sin {i} ≤q 10 km s-1 and, thus, are slow rotators. With the new calibration, projected rotational velocities have been determined for a sample of 111 late-type stars, most of which are chromospherically active. Some of the stars have had their rotational velocities measured for the first time.
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
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 Orbit Of Pi Ceti, Claud H.S. Lacy, Francis C. Fekel, Robert D. Mathieu, Nidia I. Morrell, J. A. Morse, Guillermo Torres, Daryl W. Willmarth
The Spectroscopic Orbit Of Pi Ceti, Claud H.S. Lacy, Francis C. Fekel, Robert D. Mathieu, Nidia I. Morrell, J. A. Morse, Guillermo Torres, Daryl W. Willmarth
Information Systems and Engineering Management Research Publications
π Ceti (HR 811, B7 V) has been known to be variable in its radial velocity for almost a century, but its relatively long period and small amplitude have conspired against a determination of its orbit. We have combined in an optimal fashion observations from early in this century with modern measurements to find the spectroscopic orbit with high accuracy. The orbit has a period of 7.45 years and a semiamplitude of 4.3 km/s. The measured eccentricity of e=0.00±0.07 is indistinguishable from circular, surprising for such a long period. The 76 radial velocity observations available extend over 12 cycles of …
New And Improved Parameters Of Hd 202908=Ads 14839: A Spectroscopic-Visual Triple System, Francis C. Fekel, Colin D. Scarfe, David J. Barlow, Antoine Duquennoy, Harold A. Mcalister, William I. Hartkopf, Brian D. Mason, Andrei A. Tokovinin
New And Improved Parameters Of Hd 202908=Ads 14839: A Spectroscopic-Visual Triple System, Francis C. Fekel, Colin D. Scarfe, David J. Barlow, Antoine Duquennoy, Harold A. Mcalister, William I. Hartkopf, Brian D. Mason, Andrei A. Tokovinin
Information Systems and Engineering Management Research Publications
HD 202908=ADS 14839 is a spectroscopic-visual triple system consisting of three solar-type stars. Eighteen years of spectroscopic observations including coverage of the recent periastron of 1987 January plus visual and speckle observations, the latter covering roughly the same interval as the radial velocities, have been used to obtain a simultaneous three-dimensional orbital solution. The short-period pair, Aa and Ab, has an orbital period of 3.9660465 days and a small but real eccentricity of 0.0033. The visual pair, A and B, has an orbital period of 78.5 yr and an eccentricity of 0.865. The solution yields masses for all three stars …
Properties Of Sun-Like Stars With Planets: 51 Pegasi, 47 Ursae Majoris, 70 Virginis, And Hd 114762, Gregory W. Henry, Sallie L. Baliunas, Robert A. Donahue, Willie H. Soon, Steven H. Saar
Properties Of Sun-Like Stars With Planets: 51 Pegasi, 47 Ursae Majoris, 70 Virginis, And Hd 114762, Gregory W. Henry, Sallie L. Baliunas, Robert A. Donahue, Willie H. Soon, Steven H. Saar
Information Systems and Engineering Management Research Publications
Radial velocity variations have revealed planets orbiting 51 Peg, 47 UMa, and 70 Vir, and a low-mass companion orbiting HD 114762. We analyze parallel records of photometric measurements in Strömgren b and y and Johnson V, R, and I passbands and Ca II H and K fluxes in those stars. In the case of 51 Peg, the high precision of the differential photometric measurements made by the 0.75 m Automatic Photoelectric Telescope and the nonvariability of the star would allow the detection of a transit of a planet as small as Earth (corresponding to an amplitude of 0.0001 mag) if …
Properties Of Sun-Like Stars With Planets: Ρ1 Cancri, Τ Bootis, And Υ Andromedae, Sallie L. Baliunas, Gregory W. Henry, Robert A. Donahue, Francis C. Fekel, Willie Soon
Properties Of Sun-Like Stars With Planets: Ρ1 Cancri, Τ Bootis, And Υ Andromedae, Sallie L. Baliunas, Gregory W. Henry, Robert A. Donahue, Francis C. Fekel, Willie Soon
Information Systems and Engineering Management Research Publications
Planets have been reported orbiting the Sun-like stars ρ1 Cnc, τ Boo, and υ And based on low-amplitude radial velocity variations. We have derived information on the first two stars from analysis of spectra, as well as parallel records of high-precision Strömgren b and y photometry and Ca II H + K fluxes. In the case of ρ1 Cnc, the upper limit (peak to peak) of nondetection of photometric variability at the orbital period is Δy ~ 0.0004 mag. The possibility of a planetary transit cannot be ruled out completely from the photometric data. Variations of the …