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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Evidence Of A Mira-Like Tail And Bow Shock About The Semi-Regular Variable V Cvn From Four Decades Of Polarization Measurements., Hilding R. Neilson, Richard Ignace, Beverly J. Smith, Gary Henson, Alyssa M. Adams
Evidence Of A Mira-Like Tail And Bow Shock About The Semi-Regular Variable V Cvn From Four Decades Of Polarization Measurements., Hilding R. Neilson, Richard Ignace, Beverly J. Smith, Gary Henson, Alyssa M. Adams
Richard Ignace
Discovery Of X-Ray Pulsations From A Massive Star., Lidia M. Oskinova, Yael Nazé, Helge Todt, David P. Huenemoerder, Richard Ignace, Swetlana Hubrig, Wolf-Rainer Hamann
Discovery Of X-Ray Pulsations From A Massive Star., Lidia M. Oskinova, Yael Nazé, Helge Todt, David P. Huenemoerder, Richard Ignace, Swetlana Hubrig, Wolf-Rainer Hamann
Richard Ignace
X-ray emission from stars much more massive than the Sun was discovered only 35 years ago. Such stars drive fast stellar winds where shocks can develop, and it is commonly assumed that the X-rays emerge from the shock-heated plasma. Many massive stars additionally pulsate. However, hitherto it was neither theoretically predicted nor observed that these pulsations would affect their X-ray emission. All X-ray pulsars known so far are associated with degenerate objects, either neutron stars or white dwarfs. Here we report the discovery of pulsating X-rays from a non-degenerate object, the massive B-type star ξ1 CMa. This star is …
Faraday Rotation Effects For Diagnosing Magnetism In Bubble Environments., Richard Ignace
Faraday Rotation Effects For Diagnosing Magnetism In Bubble Environments., Richard Ignace
Richard Ignace
Faraday rotation is a process by which the position angle (PA) of background linearly polarized light is rotated when passing through an ionized and magnetized medium. The effect is sensitive to the line-of-sight magnetic field in conjunction with the electron density. This contribution highlights diagnostic possibilities of inferring the magnetic field (or absence thereof) in and around wind-blown bubbles from the Faraday effect. Three cases are described as illustrations: a stellar toroidal magnetic field, a shocked interstellar magnetic field, and an interstellar magnetic field within an ionized bubble.
Disk-Outflow Models As Applied To High Mass Star Forming Regions Through Methanol And Water Maser Observations, Hontas Farmer
Disk-Outflow Models As Applied To High Mass Star Forming Regions Through Methanol And Water Maser Observations, Hontas Farmer
Hontas F Farmer
As the recent publication by Breen et al (2013) found Class II methanol masers are exclusively associated with high mass star forming regions. Based on the positions of the Class I and II methanol and H2O masers, UC H~II regions and 4.5~μm infrared sources, and the center velocities (vLSR) of the Class I methanol and H2O masers, compared to the vLSR of the Class II methanol masers, we propose three disk-outflow models that may be traced by methanol masers. In all three models, we have located the Class II methanol maser near the protostar, and the Class I methanol maser …
Convection, Granulation, And Period Jitter In Classical Cepheids., Hilding R. Neilson, Richard Ignace
Convection, Granulation, And Period Jitter In Classical Cepheids., Hilding R. Neilson, Richard Ignace
Richard Ignace
Analyses of recent observations of the sole classical Cepheid in the Kepler field, V1154 Cygni, found random changes of about 30 min in the pulsation period. These period changes challenge standard theories of pulsation and evolution because the period change is non-secular, and explaining this period jitter is necessary for understanding stellar evolution and the role of Cepheids as precise standard candles. We suggest that convection and convective hot spots can explain the observed period jitter. Convective hot spots alter the timing of flux maximum and minimum in the Cepheid light curve, hence change the measured pulsation period. We present …
Continuum Polarization In Circumstellar Media, Richard Ignace
Continuum Polarization In Circumstellar Media, Richard Ignace
Richard Ignace