[Show abstract][Hide abstract] ABSTRACT: We report the first wide-field mapping of the kinematics and stellar populations in the E3 galaxy NGC 4365. The velocity maps extend previous long-slit work. They show two independent kinematic subsystems: the central 300 pc × 700 pc rotates about the projected minor axis, and the main body of the galaxy, 3 kpc × 4 kpc, rotates almost at right angles to this. The line strength maps show that the metallicity of the stellar population decreases from a central value greater than solar to one-half solar at a radius of 2 kpc. The decoupled core and main body of the galaxy have the same luminosity-weighted age, ≈14 Gyr, and the same elevated magnesium-to-iron ratio. The two kinematically distinct components have thus shared a common star formation history. We infer that the galaxy underwent a sequence of mergers associated with dissipative star formation that ended 12 Gyr ago. The misalignment between the photometric and kinematic axes of the main body is unambiguous evidence of triaxiality. The similarity of the stellar populations in the two components suggests that the observed kinematic structure has not changed substantially in 12 Gyr.
The Astrophysical Journal 12/2008; 548(1):L33. · 6.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We present four spectra of the Type Ia supernova (SN Ia) 2006D extending from -7 to +13 days with respect to B-band maximum. The spectra include the strongest signature of unburned material at photospheric velocities observed in a SN Ia to date. The earliest spectrum exhibits C II absorption features below 14,000 km s-1, including a distinctive C II λ6580 absorption feature. The carbon signatures dissipate as the SN approaches peak brightness. In addition to discussing implications of photospheric-velocity carbon for white dwarf explosion models, we outline some factors that may influence the frequency of its detection before and around peak brightness. Two effects are explored in this regard, including depopulation of the C II optical levels by non-LTE effects, and line-of-sight effects resulting from a clumpy distribution of unburned material with low volume filling factor.
The Astrophysical Journal 12/2008; 654(1):L53. · 6.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The use of Type Ia supernovae as distance indicators led to the discovery of the accelerating expansion of the universe a decade ago. Now that large second generation surveys have significantly increased the size and quality of the high-redshift sample, the cosmological constraints are limited by the currently available sample of ~50 cosmologically useful nearby supernovae. The Nearby Supernova Factory addresses this problem by discovering nearby supernovae and observing their spectrophotometric time development. Our data sample includes over 2400 spectra from spectral timeseries of 185 supernovae. This talk presents results from a portion of this sample including a Hubble diagram (relative distance vs. redshift) and a description of some analyses using this rich dataset.
[Show abstract][Hide abstract] ABSTRACT: Virtual Control Room allows a team of people in various locations to
contribute fully to an instrument acquisition: a reduced support is
required on site but, due to the large support available off site, the
data taking quality can be still better compared to the usual on-site
support scheme. The acquisition of the SNfactory spectro-photometric
follow-up is based on such data taking model. This acquisition and its
performances are presented here.
[Show abstract][Hide abstract] ABSTRACT: The Nearby Supernova Factory reports its discovery and classification of
supernova SNF20080720-001 (J2000.0 coordinates RA 01:05:27.20 Dec
+37:51:11.05). The supernova was discovered using images obtained Jul
20.5 UTC with the QUEST-II camera on the Palomar Oschin 48-inch
telescope operated by the Palomar-QUEST Consortium, at a magnitude of
16.6, calibrated to SDSS i- band. A spectrum (range 320-1000 nm)
obtained Jul 21.6 UTC with the SuperNova Integral Field Spectrograph
(SNIFS) on the University of Hawaii 2.2- meter telescope reveals it to
be a Type Ia SN.
[Show abstract][Hide abstract] ABSTRACT: The Nearby Supernova Factory reports the discovery of the Type II
supernova SNF20070729-001 (J2000.0 coordinates RA 02:10:31.08, Decl.
02:19:59.3), at a magnitude of 19.1 in R-band derived from comparison
with the USNO-B1.0 catalog, in images obtained Jul 29 UTC using the
QUEST-II camera on the Palomar Oschin 48-inch telescope, operated by the
Palomar-QUEST Consortium. A spectrum (range 320-1000 nm) obtained Aug
01.6 UTC with the SuperNova Integral Field Spectrograph (SNIFS) on the
University of Hawaii 2.2- meter telescope was used for classification.
[Show abstract][Hide abstract] ABSTRACT: The Nearby Supernova Factory reports the discovery of 3 supernovae in
images obtained Aug 19 through Aug 20 UTC using the QUEST-II camera on
the Palomar Oschin 48-inch telescope, operated by the Palomar-QUEST
Consortium. Spectra (range 320-1000 nm) obtained with the SuperNova
Integral Field Spectrograph on the University of Hawaii 2.2-meter
telescope were used to classify each. R-band discovery magnitudes and
J2000.0 coordinates are derived from comparison with the USNO-B1.0