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Articles 1291 - 1320 of 1375

Full-Text Articles in Stars, Interstellar Medium and the Galaxy

The Luminosities Of Bright H N Regions In Ngc 628 And Its O Star Formation Rate, Ted Von Hippel, Greg Bothun Aug 1990

The Luminosities Of Bright H N Regions In Ngc 628 And Its O Star Formation Rate, Ted Von Hippel, Greg Bothun

Publications

Using narrow band CCD imaging we have identified 183 bright H n regions in the Sc galaxy NGC 628. These H n regions have luminosities which indicate that they are powered by young star clusters which contain ^ 100 ionizing stars. We attempt to reproduce the H ii region LF with and without models including stellar evolution. We find stellar evolution an important parameter in understanding the H n region LF and find that it allows star-forming galaxies to be more robust to star bursting episodes. Ranking the H n regions by luminosity and assuming that luminosity evolution is due …

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Photometry Of The Young Open Cluster Trumpler 37, Laurence A. Marschall, Neil F. Comins, Gary B. Karshner May 1990

Photometry Of The Young Open Cluster Trumpler 37, Laurence A. Marschall, Neil F. Comins, Gary B. Karshner

Physics and Astronomy Faculty Publications

Photoelectric UBV observations of 120 stars in the young open cluster Trumpler 37 are presented, primarily in the magnitude range 10.0<V

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Hd 43246 And Hd 127208: Two Unusual F-G + B Binary Systems, Robert C. Dempsey, Bernard W. Bopp, Sidney B. Parsons, Francis C. Fekel Mar 1990

Hd 43246 And Hd 127208: Two Unusual F-G + B Binary Systems, Robert C. Dempsey, Bernard W. Bopp, Sidney B. Parsons, Francis C. Fekel

Information Systems and Engineering Management Research Publications

New optical spectroscopic observations along with ultraviolet IUE observations have been obtained for the two interacting F or G III + B V binaries: HD 43246 and HD 127208. Photometric observations indicate random changes superimposed on regular ellipsoidal light variations, the latter probably the result of tidal distortion of the giant primaries. Mass transfer and loss is apparent in inverted mass ratios derived from orbital analysis, strong wind features present in the spectra, and the presence of circumsystem shells. Regular and irregular changes in the spectral features are discussed in this context.

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Sao 23229: A New Double-Lined Spectroscopic Eclipsing Binary, Laurence A. Marschall, Robert P. Stefanik, Harold L. Nations, Robert J. Davis Mar 1990

Sao 23229: A New Double-Lined Spectroscopic Eclipsing Binary, Laurence A. Marschall, Robert P. Stefanik, Harold L. Nations, Robert J. Davis

Physics and Astronomy Faculty Publications

The discovery of eclipses of the bright star SAO 23229 (HD 14384; V=6.9; Spectral Type F5 V) by Indiana observer Dan Kaiser was described in a recent article in Sky and Telescope magazine (MacRobert, 1990). Photoelectric observations by H. Landis and D. Williams, reproduced in that article, show eclipses of 0.55 mag depth and period of 2.111 days. No secondary eclipses are reported, leaving open the question of whether the system contains a very dim secondary or whether it consists of two identical stars with an actual period of 4.2 days. We report here observations that favor the latter interpretation. …

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Hr 1362: A Test Case For Stellar Dynamo Theories, Klaus G. Strassmeier, Douglas S. Hall, William S. Barksdale, Anthony T. Jusick, Gregory W. Henry Feb 1990

Hr 1362: A Test Case For Stellar Dynamo Theories, Klaus G. Strassmeier, Douglas S. Hall, William S. Barksdale, Anthony T. Jusick, Gregory W. Henry

Information Systems and Engineering Management Research Publications

An analysis of 11 yr of photometry of HR 1362 = EK Eri has shown a well-established photometric period of 335 days. This confirms an earlier period determination of about 310 days from 3 yr of APT data and is consistent with a new v sin i determination of 2 + or - 2 km/s. Recent Ca II H and K observations show moderately strong H and K emission lines at a flux level of log F prime (K) of about 6.5 ergs sq m/s. If the photometric period is interpreted as the rotation period, this surface flux is more …

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Evolution Of The Starspots In V478 Lyrae From 1980 To 1988, Douglas S. Hall, Gregory W. Henry, James R. Sowell Jan 1990

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. …

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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 Jan 1990

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. …

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Comparisons Of Sio Maser And Long-Period Variable Positions In The Aquarii And Omicron Ceti Binary Systems, J. M. Hollis, M. C. H. Wright, W. J. Welch, P. R. Jewell, H. E. Crull, Menas Kafatos, A. G. Michalitsianos Jan 1990

Comparisons Of Sio Maser And Long-Period Variable Positions In The Aquarii And Omicron Ceti Binary Systems, J. M. Hollis, M. C. H. Wright, W. J. Welch, P. R. Jewell, H. E. Crull, Menas Kafatos, A. G. Michalitsianos

Mathematics, Physics, and Computer Science Faculty Articles and Research

We have determined that the absolute position of the centroid of SiO maser-emitting spots toward both R A~r ~nd o Cet are coincident with the position of the long-period variables (LPVs) in these binary systems to within the errors of measurement. The SiO positions were determined with the Hat Creek interferometer while the LPV positions were determined with the 8 inch (20 em) transit circle of the US Naval Observatory: These results contradict an earlier report of a circumbinary SiO maser far removed from the LPV in the R Aqr binary system, and we suggest statistical reasons for the discrepancy. …

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Moderate-Resolution Spectroscopy Of The Lensed Quasar 2237+0305: A Search For Ca Ii Absorption Due To The Interstellar Medium In The Foreground Lensing Galaxy, P. Hintzen, S. P. Maran, A. G. Michalitsianos, C. B. Foltz, F. H. Chafee, Menas Kafatos Jan 1990

Moderate-Resolution Spectroscopy Of The Lensed Quasar 2237+0305: A Search For Ca Ii Absorption Due To The Interstellar Medium In The Foreground Lensing Galaxy, P. Hintzen, S. P. Maran, A. G. Michalitsianos, C. B. Foltz, F. H. Chafee, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

The gravitational lens system 2237 + 0305 consists of a low-redshift barred spiral galaxy (z = 0.0394) centered on a more distant quasar (z = 1.695). Because the lensing galaxy is nearly face on, spectroscopy of the background quasar affords a unique opportunity to study the interstellar medium in the galaxy's center and buW:. We report moderate-resolution spectroscopy of QS02237 + 0305 yielding a 3u upper limit of 72 rnA forthe rest equivalent width of Ca II K absorption d);le to gas in the intervening galaxy. Since gas in the Milky Way "thick disk" typically produces 220 mA Ca II …

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Chromospherically Active Stars. Vii. 39 Ceti=Ay Ceti, Hd185151=V1764 Cygni, And Binary Synchronization, Francis C. Fekel, Joseph J. Eitter Apr 1989

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 …

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The Photometric Variability Of The Chromospherically Active Binary Star Hd 80715, Klaus G. Strassmeier, James T. Hooten, Douglas S. Hall, Francis C. Fekel Jan 1989

The Photometric Variability Of The Chromospherically Active Binary Star Hd 80715, Klaus G. Strassmeier, James T. Hooten, Douglas S. Hall, Francis C. Fekel

Information Systems and Engineering Management Research Publications

Differential UBVRI photometry of the double-lined BY Dra system HD 80715 (K3 V + K3 V) obtained in December 1987 is presented. The star is found to be a variable with a full amplitude of 0.06 mag in V and a period similar or equal to the orbital period of 3.804 days. The mechanism of the variability is interpreted as rotational modulation due to dark starspots. In an attempt to detect chromospheric activity, high-resolution CCD spectra were obtained at Ca II H and K and at Fe I 6430 A and Ca I 6439 A, the photospheric lines normally used …

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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 Jan 1989

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 …

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Sanduleak's Star (Lmc Anonymous): Its Similarity In The Far-Ultraviolet With The Luminous Object N Carinae And Sn 1987a, A. G. Michalitsianos, Menas Kafatos, S. N. Shore Jan 1989

Sanduleak's Star (Lmc Anonymous): Its Similarity In The Far-Ultraviolet With The Luminous Object N Carinae And Sn 1987a, A. G. Michalitsianos, Menas Kafatos, S. N. Shore

Mathematics, Physics, and Computer Science Faculty Articles and Research

Spectra obtained in the far UV wavelength range 1200-2000 A with the International Ultraviolet Explorer (IUE) of the peculiar emission object LMC Anonymous, or Sanduleak's Star in the Large Magellanic Cloud, indicate the presence of circumstellar-high-excitation gas, which is rich in CNO processed material. Although LMC Anonymous is a field star whose nebular line-forming region can not be resolved, and whose mass may be considerably smaller than the massive-luminous galactic object η Carinae, the far-UV spectrum of LMC Anonymous closely resembles that of the S Condensation of η Carinae. The similarity between LMC Anonymous and the S Condensation is apparent …

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Rx Puppis: Detection Of Asymmetrical Radio Structure, J. M. Hollis, F. Yusef-Zadeh, T. J. Cornwell, R. J. Oliverson, A. G. Michalitsianos, Menas Kafatos Jan 1989

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.

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R Aquarii: Evidence For A Two-Sided Radio Jet And A Circumbinary Sio Maser, Menas Kafatos, J. M. Hollis, F. Yusef-Zadeh, A. G. Michalitsianos, M. Elitzur Jan 1989

R Aquarii: Evidence For A Two-Sided Radio Jet And A Circumbinary Sio Maser, Menas Kafatos, J. M. Hollis, F. Yusef-Zadeh, A. G. Michalitsianos, M. Elitzur

Mathematics, Physics, and Computer Science Faculty Articles and Research

We have detected collimated 4.86 GHz (~6 cm) radio continuum emission southwest (SW) of the symbiotic vanable R Aquarii by combining data corresponding to different configurations of the Very Large Array (VLA). In the xontext of a previously reported northeast (NE) 6 cm jet structure, the orientation of the newly found SW radto structure suggests bipolar symmetry, extending to distances of ~2500 AU on either side of the central H II region. The amorphous morphology of the new collimated SW structure is distinct from the discrete radio knots NE of the central object. Further, we have determined the radio spectral …

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Parenago 1540: A Pre-Main-Sequence Double-Lined Spectroscopic Binary Near The Orion Trapezium, Laurence A. Marschall, Robert D. Mathieu Dec 1988

Parenago 1540: A Pre-Main-Sequence Double-Lined Spectroscopic Binary Near The Orion Trapezium, Laurence A. Marschall, Robert D. Mathieu

Physics and Astronomy Faculty Publications

Spectroscopic and photometric observations of the star Parenago 1540 (V = 11.3), located 10 arcmin west of the Trapezium in Orion, have shown the star to be a pre-main-sequence double-lined spectroscopic binary. Thirty-seven radial-velocity measurements were obtained from which the orbital elements of the binary were determined, in particular an orbital period P = 33.73 + 0.03 days and an eccentricity of e = 0.12 + 0.01. High-dispersion spectra reveal strong Li 6707 A absorption lines in each of the components of P1540. A spectrum at lower dispersion also shows strong Ca II H and K emission lines, not …

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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 Oct 1988

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.

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A Working Catalogue Of Herbig Haro Objects, Ted Von Hippel, S.J. Bell Burnell, P.M. Williams Sep 1988

A Working Catalogue Of Herbig Haro Objects, Ted Von Hippel, S.J. Bell Burnell, P.M. Williams

Publications

We present a catalogue of 184 Herbig Haro objects from a literature search complete to 1987.5. It is intended to update the 1974 catalogue of Herbig. The catalogue contains accurate co-ordinates, proper motions, radial velocities and spectral information for these objects. A cross-reference to the two best finding charts is included. A grouping of Herbig Haro objects into is also listed.

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Chromospherically Active Stars. Iv. Hd 178450=V478 Lyr: An Early-Type By Draconis Type Binary, Francis C. Fekel Jan 1988

Chromospherically Active Stars. Iv. Hd 178450=V478 Lyr: An Early-Type By Draconis Type Binary, Francis C. Fekel

Information Systems and Engineering Management Research Publications

The variable star HD 178450 = V478 Lyr is a chromospherically active G8 V single-lined spectroscopic binary with a period of 2.130514 days. This star has strong ultraviolet emission features and a filled-in Hα absorption line which is variable in strength. It is classified as an early-type BY Draconis system and is similar in many respects to the BY Dra star HD 175742 = V775 Her. The unseen secondary of HD 178450 has a mass of about 0.3 M_sun; and is probably an M2-M3 dwarf. The inclination of the system is 67°±12°. The lithium abundance of the G8 dwarf results …

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R Aquarii: The Large-Scale Optical Nebula And The Mira Variable Position, A. G. Michalitsianos, R. J. Oliverson, J. M. Hollis, Menas Kafatos, H. E. Crull, R. J. Miller Jan 1988

R Aquarii: The Large-Scale Optical Nebula And The Mira Variable Position, A. G. Michalitsianos, R. J. Oliverson, J. M. Hollis, Menas Kafatos, H. E. Crull, R. J. Miller

Mathematics, Physics, and Computer Science Faculty Articles and Research

The R Aquarii symbiotic star system is surrounded by a large-scale optical nebula. We present observations of the nebular [O III] structure and discuss its morphological significance in context with previously observed small-scale radio-continuum features, which may be related. We suggest that a precessing accretion disk may explain the global features of both the large-scale optical emission and the small-scale radio emission. Moreover, we have determined an accurate position of the system's Mira, which suggests that a recent theoretical model, yielding an egg-shaped central H II region for symbiotic systems with certain physical parameters, may apply to R Aquarii. The …

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The C Iv Doublet Ratio Intensity Effect In Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, R. P. Fahey, R. Viotti, A. Cassatella, A. Altamore Jan 1988

The C Iv Doublet Ratio Intensity Effect In Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, R. P. Fahey, R. Viotti, A. Cassatella, A. Altamore

Mathematics, Physics, and Computer Science Faculty Articles and Research

The first successful high-resolution ultraviolet spectra in the λλ 1200-2000 wavelength range of the symbiotic variable R Aquarii and its nebular Jet were obtained in 1987 July with the International Ultraviolet Explorer (IUE). The line profile structure of the C IV λλ1548, 1550 doublet in the jet indicates multicomponent velocity structure from an optically thin emitting gas. The C IV doublet profiles in the compact H II region engulfing the Mira and hot companion binary also suggest multicomponent structure, in which the radial velocities range up to ~ -100 km s^- 1. The value of the doublet intensity ratio in …

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Chromospherically Active Stars. Iii. Hd 26337 = Ei Eri: An Rs Cvn Candidate For The Doppler-Imaging Technique, Francis C. Fekel, Robert Quigley, Kim Gillies, John L. Africano Sep 1987

Chromospherically Active Stars. Iii. Hd 26337 = Ei Eri: An Rs Cvn Candidate For The Doppler-Imaging Technique, Francis C. Fekel, Robert Quigley, Kim Gillies, John L. Africano

Information Systems and Engineering Management Research Publications

The variable star HD 26337 = EI Eri is a chromospherically active G5 IV single-lined spectroscopic binary with a period of 1.94722 days. It has moderate strength Ca II H and K emission and strong ultraviolet emission features, while Hα is a weak absorption feature that is variable in strength. The inclination of the system is 46°±12°, and the unseen secondary is most likely a late K or early M dwarf. The v sin i of the primary is 50±3 km s-1, resulting in a minimum radius of 1.9±0.1 R_sun;. A mass ratio of M1/M2 ≥ 2.6 and a mass …

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Membership In The Young Cluster Trumpler 37, Laurence A. Marschall, William F. Van Altena Jul 1987

Membership In The Young Cluster Trumpler 37, Laurence A. Marschall, William F. Van Altena

Physics and Astronomy Faculty Publications

Astrometric positions for 1387 stars and proper motions for a subset of 1135 stars brighter than V=15 in a 1.5 degree surrounding the young open cluster Trumpler 37 are presented. Membership probabilities are presented for those stars with measured proper motions, and 486 stars with probabilities of >80% are identified.

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The Large Scale Radio Structure Of R Aquarii, J. M. Hollis, Menas Kafatos, A. G. Michalitsianos, R. J. Oliverson, F. Yusef-Zadeh Jan 1987

The Large Scale Radio Structure Of R Aquarii, J. M. Hollis, Menas Kafatos, A. G. Michalitsianos, R. J. Oliverson, F. Yusef-Zadeh

Mathematics, Physics, and Computer Science Faculty Articles and Research

Radio continuum observations of the R Aquarii symbiotic star system, using the compact D configuration of the VLA at 6 em wavelength, reveal a large-scale ~2' structure engulfing the binary which has long been known to have a similar optical nebula. This optical/radio nebula possesses - 4 X 10^42 ergs of kinetic energy which is typical of a recurrent nova outburst. Moreover, a cluster of a dozen additional 6 em radio sources were observed in proximity to R Aquarii; most of these discrete sources lie ~3' south and/ or west of R Aquarii and, coupled with previous 20 cm data, …

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Supershells And Propagating Star Formation, R. Mccray, Menas Kafatos Jan 1987

Supershells And Propagating Star Formation, R. Mccray, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Stellar winds and repeated supernovae from an OB association will create a cavity of coronal gas in the interstellar medium, with radius greater than 100 pc, surrounded by a dense, expanding shell of cool interstellar gas. If the association has a typical initial mass function, its supernovae explosions will inject energy into the supershell at a nearly constant rate for about 5 x 10^7 yr. The supershell loses its interior pressure and enters the snowplow phase when radiative cooling becomes important or when the shell bursts through the gas disk of a galaxy, typically after a few times 10^7 yr …

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Chromospherically Active Stars. Ii. Hd 82558, A Young Single By Draconis Variable., Francis C. Fekel, Bernard W. Bopp, John L. Africano, Bret D. Goodrich, Leigh Hunter Palmer, Robert Quingley, Theodore Simon Nov 1986

Chromospherically Active Stars. Ii. Hd 82558, A Young Single By Draconis Variable., Francis C. Fekel, Bernard W. Bopp, John L. Africano, Bret D. Goodrich, Leigh Hunter Palmer, Robert Quingley, Theodore Simon

Information Systems and Engineering Management Research Publications

It is presently noted that the HD 82558 chromospherically active star is a young and rapidly rotating K2 V single BY Draconis variable with very strong far-UV emission features and an H-alpha line filled to the continuum level by emission. HD 82558 has constant velocity and is not a member of the Hyades Supercluster. Its light curve behavior, which appears to have been stable for several hundred rotation cycles, is reminiscent of that of the young, rapidly rotating, single K V variable H II 1883 in the Pleiades; this stability may be characteristic of young, single, chromospherically active stars.

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Evidence For Extended Radio Emission Surrounding Rx Puppis, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos Jan 1986

Evidence For Extended Radio Emission Surrounding Rx Puppis, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report evidence for ~1" extended structure in 6 cm continuum emission emanating from the symbiotic star system RX Puppis. We did not detect hourly continuum flux changes as suggested in previous radio experiments by others. Our observations indicate that the predominant nature of the radio emission is thermal and consistent with an optically thick stellar wind emanating from the symbiotic star system. Our results are discussed with regard to other similar stellar binary systems.

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The Unusual Ultraviolet Variability Of The Qso 3c 232, C. Bruhweilier, Menas Kafatos, U. J. Sofia Jan 1986

The Unusual Ultraviolet Variability Of The Qso 3c 232, C. Bruhweilier, Menas Kafatos, U. J. Sofia

Mathematics, Physics, and Computer Science Faculty Articles and Research

After examining ultraviolet IUE spectra of 18 QSOs with z > 0.35, we find that one object, 3C 232 (z = 0.533), stands out as exhibiting highly unusual spectral and continuum variability. The H 1-Lya shows at least 50% variability on a time scale of roughly a month, while the ultraviolet continuum exhibited approximately a factor of 2 decrease in a day. The magnitude of the UV continuum variability is reminiscent of that seen in the optically violent variables at visual wavelengths. Several spectral features at wavelengths shortward of H I-Lya in the rest frame are identified. A brief discussion COJ?lparing …

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Sub-Arc Second 2 Centimeter Continuum And Sio Spectral Line Observations Of R Aquarii, J. M. Hollis, A. G. Michalitsianos, Menas Kafatos, M. C. H. Wright, W. J. Welch Jan 1986

Sub-Arc Second 2 Centimeter Continuum And Sio Spectral Line Observations Of R Aquarii, J. M. Hollis, A. G. Michalitsianos, Menas Kafatos, M. C. H. Wright, W. J. Welch

Mathematics, Physics, and Computer Science Faculty Articles and Research

ub-arc second (- 0'.'15) VLA observations at 2 em have resolved the previously reported 6 em H II region, which engulfs the R Aquarii binary system, into two components. The stronger 2 em component is itself partially resolved (distorted in shape), which may be a consequence of the long-period variable (LPV) wind being subjected to the intense ionizing radiation field of the hot companion's accretion disk, which we suspect is precessing. The distorted radio contours of the central H II region may also suggest that one hemisphere of the extended LPV envelope is directly illuminated by the intense radiation field …

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Chromospherically Active Stars. I. Hd 136905., Francis C. Fekel, Douglas S. Hall, John L. Africano, Kim Gillies, Robert Quigley, Robert E. Fried Dec 1985

Chromospherically Active Stars. I. Hd 136905., Francis C. Fekel, Douglas S. Hall, John L. Africano, Kim Gillies, Robert Quigley, Robert E. Fried

Information Systems and Engineering Management Research Publications

The variable star HD 136905, recently designated GX Librae, is a chromospherically active K1 III single-lined spectroscopic binary with a period of 11.1345 days. It has moderate strength Ca II H and K and ultraviolet emission features, while Hα is strongly in absorption. The inclination of the systems is 58°±17° and the unseen secondary is most likely a G or K dwarf. The v sin i of the primary, 32±2 km s-1, results in a minimum radius of 7.0±0.4 R_sun;. Since the star fills a substantial fraction of its Roche lobe, the double-peaked light curve seen by photometric observers is …

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