Nova Sco 2001 (V1178 Sco)

We present intermediate resolution spectroscopy and near infrared photometry of NOVA Sco 2001 (V1178 Sco), which was first detected May 13th 2001 and reported June 21th 2001, and obtained by us the same day. We also retrieved very accurate astrometry of the target in this very crowded field. This is needed to be able to do follow up observations of the postnova during the next years. The spectrum shows an overall expansion of 2100 km/s and has clearly complex, and most likely nonsymmetric, outflow substructures. We clearly identify this object as classical nova, "Fe II" subclass.Comment: 4 pages, TeX, accepted for Publication in A&A (Letter

Absolute Spectrophotometry of Northern Compact Planetary Nebulae

We present medium-dispersion spectra and narrowband images of six northern compact planetary nebulae (PNe): BoBn 1, DdDm 1, IC 5117, M 1-5, M 1-71, and NGC 6833. From broad-slit spectra, total absolute fluxes and equivalent widths were measured for all observable emission lines. High signal-to noise emission line fluxes of H-alpha, H-beta, [OIII], [NII], and HeI may serve as emission line flux standards for northern hemisphere observers. From narrow-slit spectra, we derive systemic radial velocities. For four PNe, available emission line fluxes were measured with sufficient signal-to-noise to probe the physical properties of their electron densities, temperatures, and chemical abundances. BoBn 1 and DdDm 1, both type IV PNe, have an H-beta flux over three sigma away from previous measurements. We report the first abundance measurements of M 1-71. NGC 6833 measured radial velocity and galactic coordinates suggest that it is associated with the outer arm or possibly the galactic halo, and its low abundance ([O/H]=1.3x10E-4) may be indicative of low metallicity within that region.Comment: 9 pages, 1 figure, accepted in A&A (03/14/2005

The Stony Brook / SMARTS Atlas of mostly Southern Novae

We introduce the Stony Brook / SMARTS Atlas of (mostly) Southern Novae. This atlas contains both spectra and photometry obtained since 2003. The data archived in this atlas will facilitate systematic studies of the nova phenomenon and correlative studies with other comprehensive data sets. It will also enable detailed investigations of individual objects. In making the data public we hope to engender more interest on the part of the community in the physics of novae. The atlas is on-line at \url{http://www.astro.sunysb.edu/fwalter/SMARTS/NovaAtlas/} .Comment: 11 figures; 5 table

An Investigation of Gravitational Lensing in the Southern BL Lac PKS 0537-441

The BL-Lac family of active galaxies possess almost featureless spectra and exhibit rapid variability over their entire spectral range. A number of models have been developed to explain these extreme properties, several of which have invoked the action of microlensing by sub-stellar mass objects in a foreground galaxy; this not only introduces variability, but also amplifies an otherwise normal quasar source. Here we present recent spectroscopy and photometry of the southern BL Lac PKS 0537-441; with an inferred redshift of z~0.9 it represents one of the most distant and most luminous members of the BL Lac family. The goal of the observations was not only to confirm the redshift of PKS~0537-441, but also to determine the redshift of a putative galaxy along the line of sight to the BL-Lac; it has been proposed that this galaxy is the host of microlensing stars that account for PKS 0537-441's extreme properties. While several observations have failed to detect any extended emission in PKS 0537-441, the HST imaging data presented here indicate the presence of a galactic component, although we fail to identify any absorption features that reveal the redshift of the emission. It is also noted that PKS 0537-441 is accompanied by several small, but extended companions, located a few arcseconds from the point-like BL-Lac source. Two possibilities present themselves; either they represent true companions of PKS 0537-441, or are themselves gravitationally lensed images of more distant sources.Comment: 13 Pages with 4 Figures; Accepted for Publication by the Astrophysical Journa

Modelling the Recurrent Nova CI Aql in Quiescence

We present detailed photometric investigations of the recurrent nova CI Aql. New data obtained after the 2000 outburst are used to derive a 3D geometrical model of the system. The resulting light curves clearly indicate the existence of an asymmetric spray around the accretion disk, as claimed in the past e.g. for the super-soft X-ray source CAL87 in the LMC. The simulated light curves give us the mass transfer rates varying from \dot M ~ 2.5 x 10^{-8} M_\odot / yr in 1991-1996 to 5.5 x 10^{-8} < \dot M < 1.5 x 10^{-7}M_\odot / yr in 2001/2002. The distance and the interstellar foreground extinction resulting from the model are 1.55 kpc and E(B-V) = 0.98 respectively. During fast photometry sequences in 2002 short timescale variations (t ~ 13 minutes) of the mass loss are found. Moreover a change in the orbital period of the system is detectable and results in a mass loss of 2.2 x 10^{-6} < \Delta M < 5.7 x 10^{-6} M_\odot during the nova explosion.Comment: 9 pages 14 eps figures, to appear in Astron. & Astrophy

A Radio and X-Ray Study of Historical Supernovae in M83

We report the results of 15 years of radio observations of the six historical supernovae (SNe) in M83 using the Very Large Array. We note the near linear decline in radio emission from SN 1957D, a type II SN, which remains a non-thermal radio emitter. The measured flux densities from SNe 1923A and 1950B have flattened as they begin to fade below detectable limits, also type II SNe. The luminosities for these three SNe are comparable with the radio luminosities of other decades-old SNe at similar epochs. SNe 1945B, 1968L, and 1983N were not detected in the most recent observations and these non-detections are consistent with previous studies. We report the X-ray non-detections of all six historical SNe using the Chandra X-ray Observatory, consistent with previous X-ray searches of other decades-old SNe, and low inferred mass loss rates of the progenitors.Comment: 3 color ps figure

Nova light curves from the Solar Mass Ejection Imager (SMEI) - II. The extended catalogue

We present the results from observing nine Galactic novae in eruption with the Solar Mass Ejection Imager (SMEI) between 2004 and 2009. While many of these novae reached peak magnitudes that were either at or approaching the detection limits of SMEI, we were still able to produce light curves that in many cases contained more data at and around the initial rise, peak, and decline than those found in other variable star catalogs. For each nova, we obtained a peak time, maximum magnitude, and for several an estimate of the decline time (t2). Interestingly, although of lower quality than those found in Hounsell et al. (2010a), two of the light curves may indicate the presence of a pre-maximum halt. In addition the high cadence of the SMEI instrument has allowed the detection of low amplitude variations in at least one of the nova light curves

How peculiar is the ‘peculiar variable’ DZ Crucis (Nova Cru 2003)?

The variable star DZ Cru was thought to be a nova when it was discovered in eruption in 2003 August. This explanation was later challenged, however, when the first spectra of the object were reported. We present near-infrared spectroscopy of DZ Cru obtained at the New Technology Telescope on three occasions, starting ∼1.5 yr after outburst, with the aim of establishing the nature of the object. The spectra display H i, O i, [N i] emission lines, together with He i P Cygni lines superposed on a dust continuum. These observations suggest the ‘peculiar variable in Crux’ is a classical nova

Infrared Properties of Cataclysmic Variables from 2MASS: Results from the 2nd Incremental Data Release

Because accretion-generated luminosity dominates the radiated energy of most cataclysmic variables, they have been ``traditionally'' observed primarily at short wavelengths. Infrared observations of cataclysmic variables contribute to the understanding of key system components that are expected to radiate at these wavelengths, such as the cool outer disk, accretion stream, and secondary star. We have compiled the J, H, and Ks photometry of all cataclysmic variables located in the sky coverage of the 2 Micron All Sky Survey (2MASS) 2nd Incremental Data Release. This data comprises 251 systems with reliably identified near-IR counterparts and S/N > 10 photometry in one or more of the three near-IR bands.Comment: 2 pages, including 1 figure. To appear in the proceedings of The Physics of Cataclysmic Variables and Related Objects, Goettingen, Germany. For our followup ApJ paper (in press), also see http://www.ctio.noao.edu/~hoard/research/2mass/index.htm

The Globular Cluster Systems of the Sculptor Group

We use CTIO 4-m Mosaic II images taken with the Washington $CM$ and Harris $R$ filters to identify candidate globular clusters in the six major galaxies of the Sculptor group: NGC 45, NGC 55, NGC 247, NGC 254, NGC 300, and NGC 7793. From follow-up spectroscopy with Hydra-CTIO, we find 19 new globular clusters in NGC 55, NGC 247, NGC 253, and NGC 300, bringing the total number of known Sculptor group globular clusters to 36. The newly discovered clusters have spectroscopic ages consistent with those of old Milky Way globular clusters, and the majority are metal-poor. Their luminosity function closely resembles that of the Milky Way's globular clusters; their metallicity distribution is somewhat more metal-rich, but this may be the result of our color selection of candidates. The mean [$\alpha$/Fe] ratio in the clusters is $-0.2\pm0.3$, which is lower than the Milky Way average. The specific frequencies $S_N$ are similar to those of other late-type galaxies. However, if we calculate the specific frequency using the $K$-band total magnitudes of the host galaxies, we find values that are more than a factor of two higher. The kinematics of the globular cluster systems are consistent with rotation with the \ion{H}{1} disk in each of the four galaxies; however, only in NGC 253 is this result based on more than seven objects. We suggest that the Sculptor group galaxies add to evidence indicating that many of the first generation globular clusters formed in disks, not halos.Comment: 22 pages, 13 figures, 7 Tables. Full Table 3 available electronically at http://www.ctio.noao.edu/~olsen/tab3.tex. To appear in May 2004 issue of the Astronomical Journa