Emission Line Flickering from the Secondary Star in Cataclysmic Variables? A study of V3885 Sagitarii

Spectrophotometric observations of H-alpha and He I 6678 emission lines of the nova-like Cataclysmic Variable V3885 Sgr are presented and analyzed. The binary orbital period was determined as P = 0.20716071(22) days. Doppler Tomography was performed with both H-alpha and He I lines. Disc radial emissivity profiles were also computed. The tomography mapping of flickering sources was performed using the H-alpha line, from which we concluded that the flickering is not uniformly distributed on the disc. The observed tomogram of the flickering was compared with simulations, suggesting that the most intense flickering source in the H-alpha is not located in the accretion disc. It is proposed that the main line flickering source may be associated with the illuminated secondary star.Comment: 19 pages, 10 figures, 1 table. Accepted to be published on AJ. to donwload high resolution figures: http://www.astro.iag.usp.br/~fabiola/V3885_hires.pd

The large-scale ionised outflow of CH Cygni

HST and ground-based [OII} and [NII] images obtained from 1996 to 1999 reveal the existence of a ionised optical nebula around the symbiotic binary CH Cyg extending out to 5000 A.U. from the central stars. The observed velocity range of the nebula, derived from long-slit echelle spectra, is of 130 km/s. In spite of its complex appearence, the velocity data show that the basic morphology of the inner regions of the optical nebula is that of a bipolar (or conical) outflow extending nearly along the plane of the sky out to some 2000 A.U. from the centre. Even if the extension of this bipolar outflow and its position angle are consistent with those of the radio jet produced in 1984 (extrapolated to the time of our optical imagery), no obvious counterpart is visible of the original, dense radio bullets ejected by the system. We speculate that the optical bipolar outflow might be the remannt of the interaction of the bullets with a relatively dense circumstellar medium.Comment: 8 text pages + 3 figures (jpeg). ApJ in press. For a full PostScript version with figures inline see ftp://ftp.ll.iac.es/pub/research/preprints/PP252001.ps.g

Resolving the Dusty Circumstellar Structure of the Enigmatic Symbiotic Star CH Cygni with the MMT Adaptive Optics System

We imaged the symbiotic star CH Cyg and two PSF calibration stars using the unique 6.5m MMT deformable secondary adaptive optics system. Our high-resolution (FWHM=0.3"), very high Strehl (98%+-2%) mid-infrared (9.8 and 11.7 um) images of CH Cyg allow us to probe finer length scales than ever before for this object. CH Cyg is significantly extended compared to our unresolved PSF calibration stars (Mu UMa and Alpha Her) at 9.8 and 11.7 um. We estimated the size of the extension by convolving a number of simple Gaussian models with the Mu UMa PSF and determining which model provided the best fit to the data. Adopting the Hipparcos distance for this object of 270 pc, we found a nearly Gaussian extension with a FWHM at 9.8 um of ~40.5+-2.7 AU (0.15+-0.01") and a FWHM at 11.7 um of 45.9+-2.7 AU (0.17+-0.01"). After subtracting out the Gaussian component of the emission (convolved with our PSF), we found a faint \~0.7" asymmetric extension which peaks in flux ~0.5" north of the stars. This extension is roughly coincident with the northern knotlike feature seen in HST WFPC2 images obtained in 1999.Comment: 18 pages, 7 figures, accepted by the Astrophysical Journa

Planetary Nebulae: Observational Properties, Mimics, and Diagnostics

The total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is nearly 3000, double the number known a decade ago. The new discoveries are a legacy of the recent availability of wide field, narrowband imaging surveys, primarily in the light of H-alpha. In this paper, we summarise the various PN discovery techniques, and give an overview of the many types of objects which mimic PN and which appear as contaminants in both Galactic and extragalactic samples. Much improved discrimination of classical PN from their mimics is now possible based on the wide variety of high-quality multiwavelength data sets that are now available. We offer improved taxonomic and observational definitions for the PN phenomenon based on evaluation of these better diagnostic capabilities. However, we note that evidence is increasing that the PN phenomenon is heterogeneous, and PN are likely to be formed from multiple evolutionary scenarios. In particular, the relationships between some collimated symbiotic outflows and bipolar PN remain uncertain.Comment: 25 pages, 6 figures; presentation at the workshop on the Legacies of the Macquarie/AAO/Strasbourg H-alpha Planetary Nebula project, accepted by the Publications of the Astronomical Society of Australia (PASA

Speckle Interferometry of Nearby Multiple Stars. IV. Measurements in 2004 and New Orbits

The results of speckle interferometric observations of 104 binary and 6 triple stars performed at the BTA 6 m telescope in 2004 October are presented. Nearby low-mass stars are mostly observed for the program, among which 59 there are new binaries recently discovered by the Hipparcos astrometric satellite. Concurrently with the diffraction-limited position measurements we obtained 154 brightness ratio measurements of binary and multiple star components in different bands of the visible spectrum. New, first-resolved binaries are the symbiotic star CH Cyg with a weak companion at 0.043'' separation and the pair of red dwarfs, GJ 913 = HIP 118212. In addition, we derived the orbital parameters for two interferometric systems: the CN-giant pair HD 210211 = HIP 109281 (P=10.7 yr) and the G2V-K2V binary GJ 9830 = HIP 116259 (P=15.7 yr).Comment: 11 pages, 2 figures, accepted to Astrophysical Bulleti

Examining transactional influences between reading achievement and antisocially-behaving friends

The association between poorer academic outcomes and having antisocial friends is reliably demonstrated yet not well understood. Genetically sensitive designs uniquely allow for measuring genetic vulnerabilities and/or environmental risk in the association of antisocial friend behavior and poor school achievement, allowing for a better understanding of the nature of the association. This study included 233 pairs of twins from the Florida Twin Project on Reading. First, the role of antisocial friends as an environmental moderator of reading comprehension was examined. Antisocial friends significantly moderated the nonshared environmental variance in reading comprehension, with increased variation at lower levels of association with antisocial friends, with niche-picking indicated. Second, the role of reading comprehension as an environmental moderator of antisocial friends was examined. Reading comprehension significantly moderated the nonshared environmental variance in associating with antisocial friends, with increased variance at lower levels of reading comprehension and indication that common genetic influences contributed to higher reading achievement and better-behaved friends. In total, these results suggested reciprocal influences between reading achievement and antisocially-behaving friends. The impact of antisocial friends appeared to be limited in the extent to which they can undermine reading achievement, and high reading achievement appeared to support less association with antisocial friends