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The Orbits Of The Quadruple Star System 88 Tauri A From Phases Differential Astrometry And Radial Velocity, Benjamin F. Lane, Matthew W. Muterspaugh, Francis C. Fekel, Michael H. Williamson, Stanley Browne, Maciej Konacki, Bernard F. Burke, Mark M. Colavita, Shrinivas R. Kulkarni, Michael Shao Nov 2007

The Orbits Of The Quadruple Star System 88 Tauri A From Phases Differential Astrometry And Radial Velocity, Benjamin F. Lane, Matthew W. Muterspaugh, Francis C. Fekel, Michael H. Williamson, Stanley Browne, Maciej Konacki, Bernard F. Burke, Mark M. Colavita, Shrinivas R. Kulkarni, Michael Shao

Information Systems and Engineering Management Research Publications

We have used high-precision differential astrometry from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) project and radial velocity measurements covering a time span of 20 years to determine the orbital parameters of the 88 Tau A system. 88 Tau is a complex hierarchical multiple system comprising a total of six stars; we have studied the brightest four, consisting of two short-period pairs orbiting each other with an ~18 yr period. We present the first orbital solution for one of the short-period pairs, and determine the masses of the components and distance to the system to the level of …

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Chromospherically Active Stars. Xxvi. The Double-Lined Late-Type Binary Hd 19485 = Wz Arietis, Francis C. Fekel, Charles Thomas Bolton Oct 2007

Chromospherically Active Stars. Xxvi. The Double-Lined Late-Type Binary Hd 19485 = Wz Arietis, Francis C. Fekel, Charles Thomas Bolton

Information Systems and Engineering Management Research Publications

We have used spectroscopic observations to determine the orbital elements and some basic properties of the double-lined spectroscopic binary HD 19485 = WZ Ari. The orbital period is 6.247854 days, and the orbit is circular. The G5 V primary and K0 V secondary are chromospherically active. One star or possibly both are synchronously rotating. Based on the Hipparcos parallax and the magnitude differences derived in this work, we find that both components are approximately 1 mag above the zero-age main sequence, a result that is inconsistent with the assumption that the components are coeval. We discuss some possible solutions to …

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Patterns Of Photometric And Chromospheric Variation Among Sun-Like Stars: A 20 Year Perspective, G. Wesley Lockwood, Brian A. Skiff, Gregory W. Henry, Stephen M. Henry, Richard R. Radick, Sallie L. Baliunas, Robert A. Donahue, Willie Soon Jul 2007

Patterns Of Photometric And Chromospheric Variation Among Sun-Like Stars: A 20 Year Perspective, G. Wesley Lockwood, Brian A. Skiff, Gregory W. Henry, Stephen M. Henry, Richard R. Radick, Sallie L. Baliunas, Robert A. Donahue, Willie Soon

Information Systems and Engineering Management Research Publications

We examine patterns of variation of 32 primarily main-sequence Sun-like stars [selected at project onset as stars on or near the main sequence and color index 0.42 ≤ (B - V) ≤ 1.4], extending our previous 7-12 yr time series to 13-20 yr by combining Strömgren b, y photometry from Lowell Observatory with similar data from Fairborn Observatory. Parallel chromospheric Ca II H and K emission data from the Mount Wilson Observatory span the entire interval. The extended data strengthen the relationship between chromospheric and brightness variability at visible wavelengths derived previously. We show that the full range of photometric …

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The Spectroscopic And Astrometric Orbits Of Hr 672, Francis C. Fekel, Michael H. Williamson, Dimitri Pourbaix Apr 2007

The Spectroscopic And Astrometric Orbits Of Hr 672, Francis C. Fekel, Michael H. Williamson, Dimitri Pourbaix

Information Systems and Engineering Management Research Publications

From a very extensive set of radial velocities obtained at Fairborn Observatory we have computed a new spectroscopic orbit for HR 672. This binary has an orbital period of 93.290 days and an eccentricity of 0.5249. The greatly improved orbital elements have been incorporated into a new astrometric orbit, which has an inclination of 110°, from Hipparcos data. The primary is a slowly rotating early G star that is situated nearly 1 mag above the main sequence and is likely pseudosynchronously rotating. It has an iron abundance that is greater than that of the Sun. Lines of the secondary were …

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The Sun-Like Activity Of The Solar Twin 18 Scorpii, Jeffrey C. Hall, Gregory W. Henry, G. Wesley Lockwood Apr 2007

The Sun-Like Activity Of The Solar Twin 18 Scorpii, Jeffrey C. Hall, Gregory W. Henry, G. Wesley Lockwood

Information Systems and Engineering Management Research Publications

We present the results of 10 yr of complementary spectroscopic and photometric observations of the solar twin 18 Scorpii. We show that over the course of its ∼7 yr chromospheric activity cycle, 18 Sco's brightness varies in the same manner as the Sun's and with a likely total brightness variation of 0.09%, similar to the 0.1% decadal variation in the total solar irradiance.

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Butterfly Diagram And Activity Cycles In Hr 1099, Svetlana Berdyugina, Gregory W. Henry Mar 2007

Butterfly Diagram And Activity Cycles In Hr 1099, Svetlana Berdyugina, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We analyze photometric data of the active RS CVn-type star HR 1099 for the years 1975-2006 with an inversion technique and reveal the nature of two activity cycles of 15-16 yr and 5.3 ± 0.1 yr duration. The 16 yr cycle is related to variations of the total spot area and is coupled with the differential rotation, while the 5.3 yr cycle is caused by the symmetric redistribution of the spotted area between the opposite stellar hemispheres (flip-flop cycle). We recover long-lived active regions comprising two active longitudes that migrate in the orbital reference frame with a variable rate because …

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Photometry And Spectroscopy Of 11 Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry Feb 2007

Photometry And Spectroscopy Of 11 Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry

Information Systems and Engineering Management Research Publications

We have used precise photometric and high-dispersion spectroscopic observations to study 11 γ Doradus stars, 10 of them newly confirmed. Only five of these 11 γ Doradus stars appear to be single; two are primaries of double-lined spectroscopic binaries, one is the secondary of a double-lined binary, two are primaries of visual binaries and, in the case of the double-lined binary (HD 86371), either or both components could be a pulsating γ Doradus star. We have determined a preliminary orbital period of 5.32 days for the double-lined binary HD 41547. Several of the stars show spectroscopic line-profile and low-amplitude radial …

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Photospheric And Chromospheric Active Regions In Four Young Solar-Type Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, E. Marilli Feb 2007

Photospheric And Chromospheric Active Regions In Four Young Solar-Type Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, E. Marilli

Information Systems and Engineering Management Research Publications

We present a photometric and spectroscopic study of four G-K dwarfs, namely HD 166, epsilon Eri, χ1 Ori, and κ1 Cet. In three cases, we find a clear spatial association between photospheric and chromospheric active regions. For χ1 Ori we do not find appreciable variations of photospheric temperature or chromospheric Hα emission. We applied a spot/plage model to the observed rotational modulation of temperature and flux to derive spot/plage parameters and to reconstruct a rough "three-dimensional" map of the outer atmosphere of κ1 Cet, HD 166, and epsilon Eri.

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Infrared Spectroscopy Of Symbiotic Stars. V. First Orbits For Three S-Type Systems: Henize 2-173, Cl Scorpii, And As 270, Francis C. Fekel, Kenneth H. Hinkle, Richard R. Joyce, Peter R. Wood, Thomas Lebzelter Jan 2007

Infrared Spectroscopy Of Symbiotic Stars. V. First Orbits For Three S-Type Systems: Henize 2-173, Cl Scorpii, And As 270, Francis C. Fekel, Kenneth H. Hinkle, Richard R. Joyce, Peter R. Wood, Thomas Lebzelter

Information Systems and Engineering Management Research Publications

Infrared radial velocities have been used to compute first orbits of the M giants in three southern S-type symbiotic systems. Of the three, Hen 2-173 has the longest orbital period, 911 days, and also has a noncircular orbit with an eccentricity of 0.21. The large value of its mass function suggests that Hen 2-173 may be an eclipsing system. For CL Sco our spectroscopic orbital period of 626 days is essentially identical to the previously determined light variability period of 625 days, and we have adopted the latter. AS 270 has an orbital period of similar length, 671 days, and …

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The Record-Breaking Rotational Braking Of The He Strong Cp Star Hd 37776, Zdeněk Mikulášek, Jiří Krtička, Juraj Zverko, Gregory W. Henry, Jan Janik, Iosif I. Romanyuk, Jozef Ziznovsky, Hrvoje Božić, Miloslav Zejda, Thomas Graf, Martin Netolický Jan 2007

The Record-Breaking Rotational Braking Of The He Strong Cp Star Hd 37776, Zdeněk Mikulášek, Jiří Krtička, Juraj Zverko, Gregory W. Henry, Jan Janik, Iosif I. Romanyuk, Jozef Ziznovsky, Hrvoje Božić, Miloslav Zejda, Thomas Graf, Martin Netolický

Information Systems and Engineering Management Research Publications

We study the long-term light and spectral variations in the He-strong magnetic chemically peculiar star HD 37776 (V901 Ori) to search for changes of its 1.5387 d period in 1976-2007. We analyze all published photometric observations and spectrophotometry in the HeI 4026 A line. The data were supplmented with 506 new (U)VB observations obtained during the last 2 observing seasons, 66 estimates of HeI equivalent widths on 23 CFHT spectrograms and 35 of the 6-m Zeeman spectrograms. All the 1895 particular observations heve been processed simultaneously. We confirm the previously suspected increase of the period in HD 37776 which is …

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Hd 71636, A Newly Discovered Eclipsing Binary, Gregory W. Henry, Francis C. Fekel, James R. Sowell, Joel S. Gearhart Nov 2006

Hd 71636, A Newly Discovered Eclipsing Binary, Gregory W. Henry, Francis C. Fekel, James R. Sowell, Joel S. Gearhart

Information Systems and Engineering Management Research Publications

Our differential BV photometric observations, acquired with an automated telescope at Fairborn Observatory, show that HD 71636 is an eclipsing binary. From follow-up red-wavelength spectroscopic observations we classify the primary and secondary as an F2 dwarf and an F5 dwarf, respectively. The system has a period of 5.01329 days and a circular orbit. We used the Wilson-Devinney program to simultaneously solve our BV light curves and radial velocities and determined a number of fundamental properties of the system. Comparison with evolutionary tracks indicates that both stars are well ensconced on the main sequence. The age of the system is about …

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Hd 131861, A Double-Line Spectroscopic Triple System, Francis C. Fekel, Gregory W. Henry, David J. Barlow, Dimitri Pourbaix Sep 2006

Hd 131861, A Double-Line Spectroscopic Triple System, Francis C. Fekel, Gregory W. Henry, David J. Barlow, Dimitri Pourbaix

Information Systems and Engineering Management Research Publications

Our red-wavelength spectroscopic observations of HD 131861, a previously known single-line multiple system, span 20 years. Now lines of two components, the short-period F5 V primary and G8 V secondary, have been detected. The inner orbit is circular with a period of 3.5507439 days, while the outer orbit of the system has a period of 1642 days or 4.496 yr and a relatively low eccentricity of 0.10. Analysis of the Hipparcos data produces a well-determined astrometric orbit for the long-period system that has an inclination of 52°. Our photometric observations show shallow primary and secondary eclipses of the short-period pair, …

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Hr 1613: A Slowly Rotating A Dwarf Spectroscopic Binary With Solar Abundances, Francis C. Fekel, Michael H. Williamson, Christiane Buggs, Gerald Onuoha, Brittany Smith Aug 2006

Hr 1613: A Slowly Rotating A Dwarf Spectroscopic Binary With Solar Abundances, Francis C. Fekel, Michael H. Williamson, Christiane Buggs, Gerald Onuoha, Brittany Smith

Information Systems and Engineering Management Research Publications

From two sets of radial velocities we have obtained the orbital elements of HR 1613. This single-lined binary has an orbital period of 8.11128 days and a nearly circular orbit. The primary has an A9 V spectral type and a v sin i value of 11 km s-1, while the unseen secondary is likely a K or M dwarf. Spectral classifications and spectrum synthesis analysis indicate that the abundances of the primary are normal. We reject the possibility that the primary of HR 1613 is seen nearly pole-on and instead argue that its rotational inclination is at least 20°, resulting …

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New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. I. Rr Lyncis, 12 Bootis, And Hr 6169, Jocelyn Tomkin, Francis C. Fekel May 2006

New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. I. Rr Lyncis, 12 Bootis, And Hr 6169, Jocelyn Tomkin, Francis C. Fekel

Information Systems and Engineering Management Research Publications

Radial velocities from the 2.1 m telescope at McDonald Observatory supplemented with radial velocities from the coudé feed telescope at Kitt Peak National Observatory provide new precise orbits for the double-lined spectroscopic binaries RR Lyn (A3/A8/A6), 12 Boo (F8 IV), and HR 6169 (A2 V). We derive orbital dimensions (a1 sin i and a2 sin i) and minimum masses (m1 i and m2 i) with accuracies of 0.06%-0.9%. The three systems, which have V magnitudes of 5.53, 4.82, and 6.42, respectively, are all sufficiently bright that they are easily within the grasp of modern optical interferometers and so afford the …

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Infrared Spectroscopy Of Symbiotic Stars. Iv. V2116 Ophiuchi/Gx 1+4, The Neutron Star Symbiotic, Kenneth H. Hinkle, Francis C. Fekel, Richard R. Joyce, Peter R. Wood, Verne V. Smith, Thomas Lebzelter Apr 2006

Infrared Spectroscopy Of Symbiotic Stars. Iv. V2116 Ophiuchi/Gx 1+4, The Neutron Star Symbiotic, Kenneth H. Hinkle, Francis C. Fekel, Richard R. Joyce, Peter R. Wood, Verne V. Smith, Thomas Lebzelter

Information Systems and Engineering Management Research Publications

We have computed, using 17 infrared radial velocities, the first set of orbital elements for the M giant in the symbiotic binary V2116 Ophiuchi. The giant's companion is a neutron star, the bright X-ray source GX 1+4. We rule out the previously proposed period of 304 days and instead find an orbital period of 1161 days, by far the longest of any known X-ray binary. The orbit has a modest eccentricity of 0.10, with an orbital circularization time of ≲5 × 106 yr. The large mass function of the orbit significantly restricts the mass of the M giant. Adopting a …

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Rotational And Cyclical Variability In Γ Cassiopeia, Myron A. Smith, Gregory W. Henry, Ethan Vishniac Mar 2006

Rotational And Cyclical Variability In Γ Cassiopeia, Myron A. Smith, Gregory W. Henry, Ethan Vishniac

Information Systems and Engineering Management Research Publications

γ Cas is an unusual classical Be star for which the optical-band and hard X-ray fluxes vary on a variety of timescales. We report results of a 9 yr monitoring effort on this star with a robotic ground-based (APT) telescope in the B, V filter system, as well as simultaneous observations in 2004 November with this instrument and the RXTE. Our observations disclosed no correlated optical response to the rapid X-ray flares in this star, nor did the star show any sustained flux changes any time during two monitored nights in either wavelength regime. Consistent with an earlier study by …

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Spectroscopy And Photometry Of The Double-Lined Binary Hd 149420, Francis C. Fekel, Gregory W. Henry Mar 2006

Spectroscopy And Photometry Of The Double-Lined Binary Hd 149420, Francis C. Fekel, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We have used new spectroscopic and photometric observations of HD 149420 to obtain an improved orbital element solution and determine some basic properties of the system. This double-lined binary has an orbital period of 3.39430 days, a circular orbit, and a mass ratio of 0.52. The primary is somewhat evolved, with an A9 IV spectral type, while the secondary is estimated to be an F5: dwarf. The secondary may be synchronously rotating, but the primary is rotating substantially slower than its synchronous velocity. Our photometric observations confirm the light variability and period found by Hipparcos. We determine a photometric period …

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Sun In The Spectroscopic Binary Im Pegasi, The Guide Star For The Gravity Probe B Mission, Stephen C. Marsden, Svetlana Berdyugina, Jean-Francois Donati, Joel A. Eaton, Michael H. Williamson, Ilya Ilyin, Debra A. Fischer, Melesio Muñoz, Howard Isaacson, M. I. Ratner, Meïr Semel, Pascal Petit, Brad D. Carter Nov 2005

Sun In The Spectroscopic Binary Im Pegasi, The Guide Star For The Gravity Probe B Mission, Stephen C. Marsden, Svetlana Berdyugina, Jean-Francois Donati, Joel A. Eaton, Michael H. Williamson, Ilya Ilyin, Debra A. Fischer, Melesio Muñoz, Howard Isaacson, M. I. Ratner, Meïr Semel, Pascal Petit, Brad D. Carter

Information Systems and Engineering Management Research Publications

We present the first detection of the secondary of the spectroscopic binary system IM Pegasi (HR 8703), the guide star for the NASA-Stanford relativity gyroscope mission Gravity Probe B. In support of this mission, high-resolution echelle spectra of IM Peg have been obtained on an almost nightly basis. Applying the technique of least-squares deconvolution, we achieve very high signal-to-noise ratio line profiles and detect the orbit of the secondary of the system. Combining almost 700 new radial velocity measurements of both the primary and secondary of the system with previous measurements, we derive improved orbital parameters of the IM Peg …

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Chromospherically Active Stars. Xxv. Hd 144110=Ev Draconis, A Double-Lined Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Ceteka Lewis Aug 2005

Chromospherically Active Stars. Xxv. Hd 144110=Ev Draconis, A Double-Lined Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Ceteka Lewis

Information Systems and Engineering Management Research Publications

New spectroscopic and photometric observations of HD 144110 have been used to obtain an improved orbital element solution and determine some basic properties of the system. This chromospherically active, double-lined spectroscopic binary has an orbital period of 1.6714012 days and a circular orbit. We classify the components as G5 V and K0 V and suggest that they are slightly metal-rich. The photometric observations indicate that the rotation of HD 144110 is synchronous with the orbital period. Despite the short orbital period, no evidence of eclipses is seen in our photometry.

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Eleven New Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry Jun 2005

Eleven New Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry

Information Systems and Engineering Management Research Publications

We present new high-dispersion spectroscopic and precise photometric observations to identify 11 new γ Doradus variables. Seven of these new γ Doradus stars appear to be single, three are primaries of single-lined binaries, and one has two distant visual companions; none are double-lined or close visual binaries. Several of the stars show spectroscopic line-profile and low-amplitude radial velocity variability indicative of pulsation. All 11 stars are photometrically variable with amplitudes between 8 and 93 mmag in Johnson B and periods between 0.398 and 2.454 days. One star is monoperiodic; the rest have between two and five independent periods. The variability …

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Hd 8801: A Unique Single Am Star With Γ Doradus And Δ Scuti Pulsations, Gregory W. Henry, Francis C. Fekel Apr 2005

Hd 8801: A Unique Single Am Star With Γ Doradus And Δ Scuti Pulsations, Gregory W. Henry, Francis C. Fekel

Information Systems and Engineering Management Research Publications

We have discovered the first example of a star pulsating intrinsically with both γ Doradus and δ Scuti frequencies. The star, HD 8801, is an Am metallic-line star that appears to be single. Since the vast majority of Am stars are members of binary systems with periods less than 1000 days and also do not pulsate, HD 8801 possesses a very unusual, if not unique, combination of physical properties. Our photometry, acquired with an automatic telescope at Fairborn Observatory, resolves six independent pulsation periods between 0.048 and 0.404 days. The two longest periods lie within the range of γ Dor …

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Chromospherically Active Stars. Xxiv. The Giant, Single-Lined Binaries Hd 37824, Hd 181809, And Hd 217188, Francis C. Fekel, Gregory W. Henry Mar 2005

Chromospherically Active Stars. Xxiv. The Giant, Single-Lined Binaries Hd 37824, Hd 181809, And Hd 217188, Francis C. Fekel, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We have obtained spectroscopy and photometry of three chromospherically active, single-lined spectroscopic binaries, HD 37824 (V1149 Ori), HD 181809 (V4138 Sgr), and HD 217188 (AZ Psc). HD 37824 has a circular orbit with a period of 53.57 days. Its primary is a K0 III star, while the secondary is likely a G or K dwarf. HD 181809 has an orbit with a period of 13.04667 days and a low eccentricity of 0.040. The primary has a spectral type of K0 III-IV, and its secondary is probably an M dwarf. The orbit of HD 217188 has a period of 47.1209 days …

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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 Feb 2005

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 …

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A Study Of Bright Southern Long Period Variables, Thomas Lebzelter, Kenneth H. Hinkle, Peter R. Wood, Richard R. Joyce, Francis C. Fekel Feb 2005

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 …

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Hd 166181 = V815 Herculis, A Single-Lined Spectroscopic Multiple System, Francis C. Fekel, David J. Barlow, Colin D. Scarfe, Sylvie Jancart, Dimitri Pourbaix Feb 2005

Hd 166181 = V815 Herculis, A Single-Lined Spectroscopic Multiple System, Francis C. Fekel, David J. Barlow, Colin D. Scarfe, Sylvie Jancart, Dimitri Pourbaix

Information Systems and Engineering Management Research Publications

We have obtained extensive spectroscopic and velocity spectrometer observations of HD 166181, a previously known single-lined spectroscopic binary. Our improved orbit for the G6 V primary has a period of 1.8098343 days and is circular. Although the lines of additional components have not been detected, radial velocity measurements confirm that the system has additional velocity variations with a period of 2092 days, or 5.73 yr. This long-period orbit has an eccentricity of 0.76. An analysis of the Hipparcos observations produces a well-determined astrometric orbit for the long-period system that has an inclination of 78°. Mass estimates of the components in …

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Spectroscopic Orbits Of Potential Interferometric Binaries, Francis C. Fekel, Jocelyn Tomkin Oct 2004

Spectroscopic Orbits Of Potential Interferometric Binaries, Francis C. Fekel, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

We are obtaining high-resolution, red-wavelength spectra at McDonald and Kitt Peak National Observatory to improve the orbits of known spectroscopic binaries that are potential targets for ground-based optical interferometers. The combination of such observations will produce three-dimensional orbits from which very accurate masses and orbital parallaxes can be obtained for double-lined systems. This spectroscopic program will be expanded and placed on the menu of the 2 meter Automatic Spectroscopic Telescope of Tennessee State University once it commences routine operation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli Jul 2004

Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli

Information Systems and Engineering Management Research Publications

As part of our program to study stellar photospheric and chromospheric activity, we have examined several young solar type stars with activity levels intermediate between the Sun and the very active RS CVn binaries. We have analysed contemporaneous spectroscopic data obtained at Catania Observatory (Serra La Nave station, Mt. Etna) and photometric data acquired in the Stromgren bands with an automatic photometric telescope (APT) at Fairborn Observatory (Arizona, USA). Surface inhomogeneities have been detected from the rotational modulation of stellar brightness as well as from the modulation of several photospheric line-depth ratios (LDRs). The presence of chromospheric plage-like regions has …

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Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry Jul 2004

Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Chromospherically active, spotted stars generally become redder as well as fainter when large starspots rotate into view on the stellar disc. However, the RS CVn system UX Ari (a triple-lined system), becomes bluer as it gets fainter. One possible explanation is that hot, bright facular regions accompany the cool, dark photospheric spots of the active component. The bluer flux of the hotter, inactive component does not appear to be sufficient to explain the observed behaviour. We have begun a search for additional chromospherically active stars with a similar relation between colour and brightness, to investigate whether these relations can be …

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Chromospherically Active Stars. Xxiii. The Triple System Hd 7205=Qu Andromedae, Francis C. Fekel May 2004

Chromospherically Active Stars. Xxiii. The Triple System Hd 7205=Qu Andromedae, Francis C. Fekel

Information Systems and Engineering Management Research Publications

HD 7205 is a recently discovered visual binary. The primary star is a chromospherically active, single-lined binary, making the system triple. From spectroscopic observations, the orbit of the primary has a period of 18.01335 days and a moderate eccentricity of 0.197. The primary's spectral type is G8 IV-V. The unseen secondary of the short-period binary is likely an M dwarf, while the visual binary secondary is probably a K3 dwarf. From solar-abundance evolutionary tracks, the primary has a mass of ~1.0 Msolar and an age of about 10. It has evolved off the main sequence and is approaching the base …

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Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston Apr 2004

Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston

Information Systems and Engineering Management Research Publications

HD 18955 is a double-lined spectroscopic binary with a period of 43.3214 days and a high eccentricity of 0.761. The spectral types of the components are K0 V and K2-K3 V. The secondary is a typical early K dwarf, although its minimum mass is greater than canonical values. However, this larger mass is consistent with other early K dwarf, spectroscopic binary results. The primary is anomalous, being substantially underluminous for its radius and mass, which are equal to or slightly greater than solar values. A lack of lithium argues that the components are not pre-main-sequence stars. The large minimum masses …

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