Search Publications
Separate Spectra of the Components of the Low-Mass BinariesRoss 614A,B and L722-22A,B
Hershey, John L.; Chance, Don R.
The Hubble Space Telescope Faint Object Spectrograph has been used to acquire separate spectra of each of the component stars in the binaries Ross 614A,B (Gl 234A,B) and L722-22A,B (GJ 1005). Spectral types have been determined for each: M4.0 V, M5.5 V, M3.5 V, and M5.0 V, respectively, relative to a series of ground-based CCD spectra, in the 6500…
The Electron Drift Technique for Measuring Electric and Magnetic Fields
Torbert, R. B.; Quinn, J. M.; Paschmann, G. +2 more
The electron drift technique is based on sensing the drift of a weak beam of test electrons that is caused by electric fields and/or gradients in the magnetic field. These quantities can, by use of different electron energies, in principle be determined separately. Depending on the ratio of drift speed to magnetic field strength, the drift velocit…
HD 6226: a new bright B variable with occasional brightenings. Is it an unrecognized Be star?
Harmanec, P.; Bozic, H.
An analysis of differential UBV measurements of HD 6226 secured between 1982 and 1995 at Hvar, and combined with the Hipparcos satellite H_p photometry, led to the finding that this infrequently observed star is a new variable, characterized by occasional brightenings accompanied by the reddening of the B-V, and blueing of the U-B index. We note t…
Evolution of Southern Star-Forming Regions
Thi, W. F.; Burgdorf, M.; van Dishoeck, E. F. +5 more
We present ISO observations of bright, high-mass southern starforming regions with the Short Wavelength Spectrometer (SWS) and Long Wavelength Spectrometer (LWS). The selected targets show a range of pre-main sequence evolutionary phases. Whereas some objects still show interstellar ice features, the most evolved objects are coincident with ultra-…
Particle propagation channel detected at 4.7 AU inside a corotating interaction region
Pick, M.; Lanzerotti, L. J.; Sarris, E. T. +5 more
This study presents an interplanetary particle (electrons and ions) event which was detected at 4.7 AU by the instruments on the Ulysses spacecraft inside a corotating interaction region between a fast and slow solar wind stream. A particle propagation channel is identified where the particles can propagate from the Sun nearly scatter free within …
Diffuse Ionized Gas in the beta CMa Tunnel
Gry, C.; Dupin, O.
We present HST observations of the interstellar medium toward the star beta CMa known to be located in a low density extension of the Local Bubble. Most of the matter in the sight-line is ionized and clumped in two main components. One of them, as well as one of the components detected toward epsilon CMa, is mostly ionized and only slightly deplet…
Diffuse Dark and Bright Objects in the Hubble Deep Field
Park, Changbom; Kim, Juhan
In the Hubble Deep Field (HDF) we have identified candidate regions where primordial galaxies might be forming. These regions are identified from negative or positive peaks in the difference maps obtained from the HDF maps smoothed over 0.8" and 4". They have apparent V magnitudes typically between 29 and 31 (missing flux below the local average l…
EUV Spectral Variability and Non-Equilibrium Ionisation in the 'Quiet' Sun
Harrison, R. A.; Lanzafame, A. C.; Brooks, D. H. +2 more
Recent spectroscopic observations by the Solar and Heliospheric Observatory (SOHO) have revealed the dynamic nature of even the 'quiet' Sun. Spectral variability data clearly show that dynamics in the solar upper atmosphere take place on timescales shorter than those of ionisation relaxation. Accuracy in the interpretation of diagnostic spectral d…
Infrared Space Observatory Mapping of 60 Micron Dust Emission around Vega-Type Systems: Erratum
Stencel, R. E.; Backman, D. E.; Fajardo-Acosta, S. B.
In the Letter ``Infrared Space Observatory Mapping of 60 Micron Dust Emission around Vega-type Systems'' by S. B. Fajardo-Acosta, R. E. Stencel, and D. E. Backman (ApJ, 487, L151 [1997]), there is an error in the equatorial coordinates that we assigned to our maps. Using preliminary versions of the PHOT Interactive Analysis (PIA) program, we incor…
The Absolute Magnitude of RR Lyraes: from HIPPARCOS Parallaxes and Proper Motions
Solano, E.
We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae stars. In addition, we have used the HIPPARCOS parallax of RR Lyr itself to determine its absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae Mv,[…