Search Publications

Time Variability of FUV Emission from Cool Stars on Multi-year Timescales

France, Kevin; Youngblood, Allison; Kamgar, Leo

The physical and chemical properties of planetary atmospheres are affected by temporal evolution of ultraviolet (UV) radiation inputs from their host stars at all time scales. While studies of X-ray/UV flare properties and long-term stellar evolution of exoplanet host stars have provided new constraints regarding stellar inputs to exoplanetary sys…

Consistent Dust and Gas Models for Protoplanetary Disks. III. Models for Selected Objects from the FP7 DIANA Project

Waters, L. B. F. M.; Pinte, C.; Woitke, P. +17 more

The European FP7 project DIANA has performed a coherent analysis of a large set of observational data of protoplanetary disks by means of thermo-chemical disk models. The collected data include extinction-corrected stellar UV and X-ray input spectra (as seen by the disk), photometric fluxes, low and high resolution spectra, interferometric data, e…

Ultraviolet Activity as Indicators of Small-scale Magnetic Fields in γ Cassiopeiae

Smith, Myron A.

The recorded activity of γ Cas (B0.5 IVe) in the ultraviolet is important to an understanding of the mechanism behind this prototypical Be star’s high-energy activity, especially its hard X-ray emissions. The analysis here focuses first on the phasing of ultraviolet and optical light curves from different epochs. The rotational interpretation of t…

Mass Outflow from Cool Giants in Symbiotic Stars

Shagatova, Natalia

New Gapless COS G140L Mode Proposed for Background-limited Far-UV Observations

Anderson, Scott F.; France, Kevin; Fleming, Brian +6 more

Here we describe the observation and calibration procedure for a new G140L observing mode for the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST). This mode, CENWAV = 800, is designed to move the far-UV band fully onto the Segment A detector, allowing for more efficient observation and analysis by simplifying calibratio…

Elemental Abundance Analyses with DAO Spectrograms. XXXVI. The Hot Metallic Line Stars Theta Leonis and Omicron Pegasi

Adelman, Saul J.; Gulliver, Austin F.; Heaton, Robert J.

Hot Gaseous Stellar Disks Avoid Regions of Low Interstellar Densities

Abt, Helmut A.

Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared

Gordon, Karl D.; Tremblay, P. -E.; Bohlin, Ralph C.

The measurement of precise absolute fluxes for stellar sources has been pursued with increased vigor since the discovery of the dark energy and the realization that its detailed understanding requires accurate spectral energy distributions (SEDs) of redshifted Ia supernovae in the rest frame. The flux distributions of spectrophotometric standard s…

Mg II h + k Flux—Rotational Period Correlation for G-type Stars

Bertone, Emanuele; Olmedo, Manuel; Chávez, Miguel +1 more

We present an analysis of the correlation between the mid-UV Mg II h and k emission lines and measured rotational periods of G-type stars. Based on IUE and HST high resolution spectra of a sample of 36 stars, we derive an exponential function that best represents the correlation. We found that the variation of the Mg II h + k fluxes is about a fac…

Interstellar Dust Models Towards Some IUE Stars

Gupta, R.; Katyal, N.; Vaidya, D. B.

We study the extinction properties of the composite dust grains, consisting of host silicate spheroids and graphite as inclusions, using discrete dipole approximation (DDA). We calculate the extinction cross sections of the composite grains in the ultraviolet spectral region, 1200Å-3200Åand study the variation in extinction as a function of the vo…