Search Publications
Narrow Lines in Type II Supernovae: Probing the Circumstellar Nebulae of the Progenitors
Van Dyk, Schuyler D.; Chu, You-Hua; Gruendl, Robert A. +1 more
We have carried out a high-dispersion (R~30,000) echelle spectroscopic survey of 16 Type II supernovae (SNe) to search for narrow emission lines from circumstellar nebulae ejected by their massive progenitors. Circumstellar nebulae, if detected, provide invaluable opportunities to probe SN progenitors. Of the 16 SNe observed, SN ejecta are clearly…
Response of interplanetary glow to global variations of hydrogen ionization rate and solar Lyman α flux
Bzowski, Maciej; Summanen, Tuula; Ruciński, Daniel +1 more
The aim of the paper is to investigate the influence of the solar cycle variations of the radiation pressure and time- and heliolatitude-dependent ionization rate on the spatial distribution and temporal evolution of the interplanetary hydrogen Lyman α glow, observed from 1 AU. We identify the variables affecting the distribution and evolution of …
Hubble Space Telescope Survey of Clusters in Nearby Galaxies. II. Statistical Analysis of Cluster Populations
Dolphin, Andrew E.; Kennicutt, Robert C., Jr.
We present a statistical system that can be used in the study of cluster populations. The basis of our approach is the construction of synthetic cluster color-magnitude-radius diagrams (CMRDs), which we compare with the observed data using a maximum likelihood calculation. This approach permits a relatively easy incorporation of incompleteness (a …
The origin of the strings in the outer regions of η Carinae
Redman, M. P.; Meaburn, J.; Holloway, A. J.
The narrow optical filaments (`strings' or `spikes') emerging from the Homunculus of η Carinae are modelled as resulting from the passage of ballistic `bullets' of material through the dense circumstellar environment. In this explanation, the string is the decelerating flow of ablated gas from the bullet. An archive Hubble Space Telescope image an…
Study of the Per OB2 star-forming complex. I. The Compiled Catalogue of kinematic and photometric data
Scholz, R. -D.; Yatsenko, A. I.; Piskunov, A. E. +3 more
In this paper we describe the construction of a Compiled Catalogue (CC) of about 30 000 stars in a nearby region of star formation including the Per OB2 association. The CC is a photometric and astrometric survey with the center at (alpha ,delta )_J2000=(3h51m36s, 34o36arcmin ) and radius of 10 degrees. …
Systematic errors in measuring solar magnetic fields with a FPI spectrometer and MDI
Carroll, T. A.; Norton, A. A.; Settele, A. +1 more
We will show the potential errors of observations using instruments, where a line spectrum is obtained not instantly but by scanning through the spectral line in time. We give two examples in simulations of a sunspot observation with the measuring procedure of a typical Fabry-Perot interferometer (FPI) spectrometer and the Michelson Doppler Imager…
A revision of the fundamental parameters of the open cluster Hogg 15 and the projected star WR 47
Bica, E.; Piatti, A. E.; Santos, J. F. C., Jr. +1 more
We revise the fundamental parameters of the faint open cluster Hogg 15, for which two recent colour-magnitude diagram (CMD) studies have obtained significantly different ages. In the present study, we combine a series of methods trying to constrain age, together with other fundamental parameters. We employ spatial extractions to construct the CMDs…
Kinematics of OB Stars
Branham, Richard L., Jr.
The kinematics of 1817 stars of class O-B5 are examined. The 1655 stars with distances up to 1 kpc are taken from the Hipparcos catalog and 162 stars with distances greater than 1 kpc from Westlin's study of OB stars. The Ogorodnikov-Milne model of Galactic kinematics, with Edmondson's second-order terms included, is used for the equations of cond…
Bulk flow velocities in the solar corona at solar maximum
Simnett, G. M.; Lewis, D. J.
We present velocity estimates of bulk motions seen in the solar corona by the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft. These estimates reflect the mass-weighted mean outflow of all coronal mass ejections (CMEs) seen during a 1-yr period on the approach to solar maximum. The par…
XMM-Newton observes flaring in the polar UZ For during a low state
Pandel, Dirk; Córdova, France A.
During an XMM-Newton observation, the eclipsing polar UZ For was found in a peculiar state with an extremely low X-ray luminosity and occasional X-ray and ultraviolet (UV) flaring. For most of the observation, UZ For was only barely detected in X-rays and ~800 times fainter than during a high state previously observed with ROSAT. A transient event…