660 research outputs found
High speed photometry of faint cataclysmic variables - VI. Car2, V1040 Cen, Ha 075648, IL Nor (Nova Nor 1893), HS Pup (Nova Pup 1963), SDSS J2048-06, CSS 081419-005022 and CSS 112634-100210
We have observed 8 faint cataclysmic variable stars photometrically. The
nova-like Car2 was extensively sampled but showed little variability. V1040 Cen
was observed near the end of a dwarf nova outburst and possessed dwarf nova and
quasi-periodic oscillations. Ha 075648 has strong large amplitude flickering
and a possible orbital modulation at 3.49 h. The correct identification for the
nova remnant IL Nor (Nova Nor 1893) has been established. HS Pup (Nova Pup
1963) has a possible orbital period of 3.244 h. SDSS J2048-06 is a low mass
transfer dwarf nova that in quiescence shows slow variations at 7.67 h (though
poorly sampled with our observations) and an orbital modulation at 87.26 min.
The dwarf nova CSS 081419-005022 has an orbital period of 1.796 h and the
eclipsing dwarf nova CSS 112634-100210 has an orbital period of 1.8581 h.Comment: 7 pages, 15 figures. Accepted for publication in MNRA
Observations of Faint Eclipsing Cataclysmic Variables
We present time-resolved photometry of six faint (V>17mag) cataclysmic
variables (CVs); one of them is V849 Oph and the others are identified from the
Sloan Digital Sky Survey (SDSS J0920+0042, SDSS J1327+6528, SDSS J1227+5139,
SDSS J1607.02+3623, SDSS J1457+5148). The optical CCD photometric observations
of these objects were performed at the T\"UB\.ITAK National Observatory
(Turkey) between February 2006 and March 2009. We aimed to detect short time
scale orbital variability arisen from hot-spot modulation, flickering
structures which occur from rapid fluctuations of material transferring from
red star to white dwarf and orbital period changes for selected short-period
(P<4h) CVs at quiescence. Results obtained from eclipse timings and light
curves morphology related to white dwarf stars, accretion disks and hot-spots
are discussed for each system. Analysis of the short time coverage of data,
obtained for SDSS J1227+5139 indicates a cyclical period change arisen from
magnetic activity on the secondary star. Photometric period of SDSS J1607+3623
is derived firstly in this study, while for the other five systems light
elements are corrected using the previous and new photometric observations. The
nature of SDSS J1457+5148 is not precisely revealed that its light curve shows
any periodicity that could be related to the orbital period
The new AM CVn star in Hydra
High speed photometry of the new AM CVn star in Hya (previously known as
SN2003aw), spectroscopically identified by Chornock & Filippenko, shows it to
have a superhump period of 2041.5 +/- 0.3 s. We find a range of brightness from
V ~ 16.5 to 20.3, presumably caused by variations in the rate of mass transfer.
In the intermediate state the system cycles in brightness with a period of ~ 16
h and range >= 0.4 mag. There are sidebands to the principal frequencies in the
Fourier transform which have constant frequency difference from the superhump
harmonics.Comment: 5 pages, 6 figures. Accepted for publication in MNRA
Spectroscopy and near-infrared photometry of the helium nova V445 Puppis
Nova Puppis 2000 (V445 Pup) has been proposed as the first example of a
helium nova. Recent optical spectroscopy of V445 Pup at V=19.91 mag obtained
with IMACS on the 6.5-m Magellan telescope, shows that the spectrum consists of
HeI, [OI], [OII] and [OIII] emission lines and no hydrogen is present. The
spectroscopy shows an expanding nova shell with blue- and redshifted velocity
components around +/- 850 km/s and +/- 1600 km/s. Images taken with Magellan
under very good seeing conditions (FWHM ~ 0.6") shows V445 Pup to be extended
(full width at zero intensity ~ 1.9") and elongated (position angle ~ 150deg).
We have followed the secular evolution of V445 Pup since the decline from
(optical) maximum, at near-infrared wavelengths (J, H and Ks) using the
Infrared Survey Facility (IRSF) at the Sutherland site of the South African
Astronomical Observatory. We find that V445 Pup is still covered by a dense
dust shell more than three years after its outburst.Comment: 2 pages, 1 figure. To appear in `The Astrophysics of Cataclysmic
Variables and Related Objects', eds. J.M. Hameury and J.P. Lasota (ASP Conf.
Ser.
The Norma cluster (ACO3627): II. The near infrared K_s-band luminosity function
A deep K_s-band photometric catalogue of galaxies at the core of the rich,
nearby Norma cluster (ACO3627) is presented. The survey covers about 45 by 45
square arcmin (slightly less than 1/3 Abell radius), which corresponds to
approx. 0.8 Mpc^2 at the adopted distance (v_cmb/H0) of 70 Mpc of this cluster.
The survey is estimated to be complete to a magnitude of M_Ks <~ -19.5 mag.
This extends into the dwarf regime, 6 magnitudes below M_Ks*. The catalogue
contains 390 objects, 235 of which are classified as likely or definite
galaxies and 155 as candidate galaxies. The Ks-band luminosity function (LF) is
constructed from the photometric sample, using a spectroscopic subsample to
correct for fore- and background contamination. We fit a Schechter function
with a characteristic magnitude of M_Ks* = -25.39 \pm 0.80 mag and faint-end
slope of alpha = -1.26 \pm 0.10 to the data. The shape of the LF is similar to
those found in previous determinations of the cluster LF, in both optical and
near infrared. The Schechter parameters agree well with those of recent field
LFs, suggesting that both the shape of the bright end and the faint end slope
are relatively insensitive to environment.Comment: 18 pages, 6 figures, 8 tables (includes full photometric catalogue as
appendix), accepted for publication in MNRA
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