4 research outputs found
The Type Ia Supernova 1999aw: a Probable 1999aa-like Event In a Low-Luminosity Host Galaxy
SN 1999aw was discovered during the first campaign of the Nearby Galaxies
Supernova Search (NGSS) project. This luminous, slow-declining (Delta m_{15}
(B) = 0.81 \pm 0.03) Type Ia supernova was noteworthy in at least two respects.
First, it occurred in an extremely low luminosity host galaxy that was not
visible in the template images, nor in initial subsequent deep imaging.
Secondly, the photometric and spectral properties of this supernova indicate
that it very likely was similar to the subclass of Type Ia supernovae whose
prototype is SN 1999aa. This paper presents the BVRI and J_{s} HK_{s}
lightcurves of SN 1999aw (through 100 days past maximum light), as well as
several epochs of optical spectra. From these data we calculate the bolometric
light curve, and give estimates of the luminosity at maximum light and the
initial ^{56}Ni mass. In addition, we present deep BVI images obtained recently
with the Baade 6.5-meter telescope at Las Campanas Observatory which reveal the
remarkably low-luminosity host galaxy.Comment: 18 pages, 10 figures, 8 tables, accepted for publication in A
Allan Sandage and the Cosmic Expansion
This is an account of Allan Sandage's work on (1) The character of the
expansion field. For many years he has been the strongest defender of an
expanding Universe. He later explained the CMB dipole by a local velocity of
220 +/- 50 km/s toward the Virgo cluster and by a bulk motion of the Local
supercluster (extending out to ~3500 km/s) of 450-500 km/s toward an apex at
l=275, b=12. Allowing for these streaming velocities he found linear expansion
to hold down to local scales (~300 km/s). (2) The calibration of the Hubble
constant. Probing different methods he finally adopted - from
Cepheid-calibrated SNe Ia and from independent RR Lyr-calibrated TRGBs - H_0 =
62.3 +/- 1.3 +/- 5.0 km/s/Mpc.Comment: 12 pages, 11 figures, 1 table, Submitted to Astrophysics and Space
Science, Special Issue on the Fundamental Cosmic Distance Scale in the Gaia
Er
Binary systems and their nuclear explosions
Peer ReviewedPreprin