Search Publications
Is There a Metallicity-Luminosity Relationship in Active Galactic Nuclei? The Case of Narrow-Line Seyfert 1 Galaxies
Netzer, Hagai; Shemmer, Ohad
The well-known relationship between metallicity and luminosity in active galactic nuclei (AGNs) is addressed by introducing new metallicity measurements (based on the method of Hamann & Ferland, hereafter HF) for a sample of narrow-line Seyfert 1 galaxies (NLS1s). Our new results, based on a sample of 162 AGNs, including nine NLS1s, indicate t…
A Hubble Space Telescope Snapshot Survey of Nearby Supernovae
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Modjaz, Maryam +4 more
We present photometry of 13 recent supernovae (SNe) recovered in a Hubble Space Telescope Snapshot program and tie the measurements to earlier ground-based observations in order to study the late-time evolution of the SNe. Many of the ground-based measurements are previously unpublished and were made primarily with a robotic telescope, the Katzman…
Evidence for Cluster Evolution from an Improved Measurement of the Velocity Dispersion and Morphological Fraction of Cluster 1324+3011 at z=0.76
Postman, Marc; Lubin, Lori M.; Oke, J. B.
We have carried out additional spectroscopic observations in the field of cluster Cl 1324+3011 at z=0.76. Combined with the spectroscopy recently presented by Postman, Lubin, & Oke, we now have spectroscopically confirmed 47 cluster members. With this significant number of redshifts, we measure accurately the cluster velocity dispersion to be …
Supernova 1998bw - the final phases
Panagia, N.; Sollerman, J.; Lundqvist, P. +10 more
The probable association with
86 GHz SiO maser survey of late-type stars in the Inner Galaxy. I. Observational data
Menten, K. M.; Omont, A.; Habing, H. J. +2 more
We present 86 GHz (v = 1, J = 2 -> 1) SiO maser line observations with the IRAM 30-m telescope of a sample of 441 late-type stars in the Inner Galaxy ( -4 degr < l < +30 degr ). These stars were selected on the basis of their infrared magnitudes and colours from the ISOGAL and MSX catalogues. SiO maser emission was detected in 271 sources…
The Gravitational Lens-Galaxy Group Connection. I. Discovery of a Group Coincident with CLASS B0712+472
Fassnacht, C. D.; Lubin, L. M.
Previous observations of the environments of the lensing galaxies in gravitational lens systems suggest that many of the lensing galaxies are associated with small groups of galaxies. As a result, we have begun a coordinated program to study the local environments of all known gravitational lens systems. In this paper, we present results on the gr…
Decay of sunspots
Martínez Pillet, V.
The photometric decay of sunspots is studied in some detail. Aspects related to leader vs. follower sunspot decay are presented and our current understanding of the physical mechanisms involved critically reviewed. The intrinsic instability of follower spots to form a stable sunspot cannot be understood in terms of the fluting stability as propose…
Mass Loss and Jet Outflow in the Orion Nebula Proplyd LV 2
O'Dell, C. R.; Henney, W. J.; Meaburn, J. +2 more
We have obtained Hubble Space Telescope (HST) Space Telescope Imaging Spectrometer high-resolution spectra of the Orion proplyd LV 2 in the C III doublet at 1906.68 and 1908.73 Å. New images at the 6 cm wavelength with MERLIN complement earlier HST images at a similar spatial resolution. This object is one of the closest proplyds to θ1 …
The ARAUCARIA Project: Deep Near-Infrared Survey of Nearby Galaxies. I. The Distance to the Large Magellanic Cloud from K-Band Photometry of Red Clump Stars
Gieren, W.; Pietrzyński, G.
We have obtained deep imaging in the near-infrared J and K bands for two nearby fields in the bar of the LMC with the ESO New Technology Telescope, under exquisite seeing conditions. The K, J-K color-magnitude diagrams constructed from these data are of outstanding photometric quality and reveal the presence of several hundred red clump stars. Usi…
Oscillations Above Sunspots
Fredvik, T.; Kjeldseth-Moe, O.; Brynildsen, N. +1 more
The 3-min oscillations in the sunspot atmosphere are discussed, based on joint observing with the Transition Region and Coronal Explorer - TRACE and the Solar and Heliospheric Observatory - SOHO. We find that the oscillation amplitude above the umbra increases with increasing temperature, reaches a maximum for emission lines formed close to 1-2× 1…