237 research outputs found
Spectroscopy of Stellar-Like Objects Contained in the Second Byurakan Survey. I
The results of spectroscopic observations of 363 star-like objects from the
Second Byurakan Survey (SBS) are reported. This SBS's subsample has proven to
be a rich source of newly identified quasars, Seyfert type galaxies, degenerate
stars and hot subdwarfs. In the subsample here studied, we identified 35 new
QSOs, 142 White Dwarfs (WDs) the majority of which, 114 are of DA type, 55
subdwarfs (29 of which are sdB-type stars), 10 HBB, 16 NHB, 54 G-type and 25
F-type stars, two objects with composite spectra, four Cataclismic Variables
(CV), two peculiar emission line stars, 17 objects with continuous spectra, as
well as one planetary nebula. Among the 35 QSOs we have found two Broad
Absorption Line (BAL) QSOs, namely SBS 1423+500 and SBS 1435+500A. Magnitudes,
redshifts, and slit spectra for all QSOs, also some typical spectra of the
peculiar stars are presented. We estimate the minimum surface density of bright
QSOs in redshift range 0.3<z<2.2 to be 0.05 per sq. deg. for B<17.0 and 0.10
per sq. deg. for B<17.5.Comment: 22 pages, 3 tables, 4 figures, PASP in pres
Spectral Observations of Faint Markarian Galaxies of the Second Byurakan Survey. II
We continue the program of spectroscopic observations of objects from the
Second Byurakan Survey (SBS). This survey contains more than 1300 galaxies and
1700 star-like objects with m(pg)<19.5. Our work is aimed towards the
construction of a complete sample of faint Markarian galaxies. Here, we present
spectroscopic data for 43 galaxies. Amongst them six new Seyfert galaxies are
found, namely two Sy 1 type (SBS 1343+544 and SBS 1433+500), one Sy 2 type (SBS
1620+545) and three likely Sy 2 type galaxies (SBS 1205+556, SBS 1344+527, SBS
1436+597). SBS 1343+544 falls into the luminosity gap between low-redshift QSOs
and high luminosity Sefert galaxies. In the sample studied here, another 36
emission-line galaxies were spectroscopically confirmed. Thus far, 102 SBS
galaxies brighter than m(pg)=17.5 have been observed with the Cananea 2.1m GHO
telescope. The apparent magnitude and redshift distributions, the spectral
classification, the relative intensities of emission lines, and other
parameters, as well as slit spectra for all 43 observed galaxies are presented.Comment: 7 pages, 7 figures, 2 tables, Latex, aaspp4.sty and aj_pt.sty,
Submitted to Astronomical Journa
Spectroscopic Analysis of H I Absorption Line Systems in 40 HIRES Quasars
We list and analyze H I absorption lines at redshifts 2 < z < 4 with column
density (12 < log(N_HI) < 19) in 40 high-resolutional (FWHM = 8.0 km/s) quasar
spectra obtained with the Keck+HIRES. We de-blend and fit all H I lines within
1,000 km/s of 86 strong H I lines whose column densities are log(N_HI/[cm^-2])
> 15. Unlike most prior studies, we use not only Lya but also all visible
higher Lyman series lines to improve the fitting accuracy. This reveals
components near to higher column density systems that can not be seen in Lya.
We list the Voigt profile fits to the 1339 H I components that we found. We
examined physical properties of H I lines after separating them into several
sub-samples according to their velocity separation from the quasars, their
redshift, column density and the S/N ratio of the spectrum. We found two
interesting trends for lines with 12 < log(N_HI) < 15 which are within 200-1000
km/s of systems with log(N_HI) > 15. First, their column density distribution
becomes steeper, meaning relatively fewer high column density lines, at z <
2.9. Second, their column density distribution also becomes steeper and their
line width becomes broader by about 2-3 km/s when they are within 5,000 km/s of
their quasar.Comment: 32 pages, 14 figures, accepted for publication in the Astronomical
Journal. A complete version with all tables and figures is available at
http://www.astro.psu.edu/users/misawa/pub/Paper/40hires.ps.g
Optical Microvariability in Quasars: Spectral Variability
We present a method that we developed to discern where the optical
microvariability (OM) in quasars originates: in the accretion disk (related to
thermal processes) or in the jet (related to non-thermal processes). Analyzing
nearly simultaneous observations in three different optical bands of continuum
emission, we are able to determine the origin of several isolated OM events. In
particular, our method indicates that from nine events reported by Ramirez et
al. (2009), three of them are consistent with a thermal origin, three to
non-thermal, and three cannot be discerned. The implications for the emission
models of OM are briefly discussed.Comment: Accepted for publication in the Astrophysical Journa
Rapid Oscillations in Cataclysmic Variables. XVI. DW Cancri
We report photometry and spectroscopy of the novalike variable DW Cancri. The
spectra show the usual broad H and He emission lines, with an excitation and
continuum slope characteristic of a moderately high accretion rate. A
radial-velocity search yields strong detections at two periods, 86.1015(3) min
and 38.58377(6) min. We interpret these as respectively the orbital period
P_orb of the binary, and the spin period P_spin of a magnetic white dwarf. The
light curve also shows the spin period, plus an additional strong signal at
69.9133(10) min, which coincides with the difference frequency
1/P_spin-1/P_orb. These periods are stable over the 1 year baseline of
measurement.
This triply-periodic structure mimics the behavior of several
well-credentialed members of the "DQ Herculis" (intermediate polar) class of
cataclysmic variables. DQ Her membership is also suggested by the mysteriously
strong sideband signal (at nu_spin-nu_orb), attesting to a strong pulsed flux
at X-ray/EUV/UV wavelengths. DW Cnc is a new member of this class, and would be
an excellent target for extended observation at these wavelengths.Comment: PDF, 28 pages, 6 tables, 9 figures; accepted, in press, to appear
June 2004, PASP; more info at http://cba.phys.columbia.edu
Multiband Comparative Study of Optical Microvariability in RL vs. RQ Quasars
We present the results of an optical multi-band (BVR) photometric monitoring
program of 22 core-dominated radio-loud quasars (CRLQs) and 22 radio-quiet
quasars (RQQs). The aim was to compare the properties of microvariability in
both types of quasars. We detected optical microvariability in 5 RQQs and 4
CRLQs. Our results confirm that microvariability in RQQs may be as frequent as
in CRLQs. In addition we compare microvariability duty cycles in different
bands. Finally, the implications for the origin of the microvariations are
briefly discussed.Comment: 17 pages, 14 figures, Accepted for publication in the Astronomical
Journa
Very-high-energy gamma radiation associated with the unshocked wind of the Crab pulsar
We show that the relativistic wind in the Crab pulsar, which is commonly
thought to be invisible in the region upstream of the termination shock at R <
0.1 pc, in fact could be directly observed through its inverse Compton gamm-ray
emission. The search for such specific component of radiation in the gamma-ray
spectrum of the Crab can provide unique information about the unshocked pulsar
wind that is not accessible at other wavelengths.Comment: 11 pages, 11 figures, to appear in one of the April issues of MNRA
The Second Byurakan Survey Galaxies. I. The Optical Database
A database for the entire catalog of the Second Byurakan Survey (SBS)
galaxies is presented. It contains new measurements of their optical parameters
and additional information taken from the literature and other databases. The
measurements were made using Ipg(near-infrared), Fpg(red) and Jpg(blue) band
images from photographic sky survey plates obtained by the Palomar Schmidt
telescope and extracted from the STScI Digital Sky Survey (DSS). The database
provides accurate coordinates, morphological type, spectral and activity
classes, apparent magnitudes and diameters, axial ratios, and position angles,
as well as number counts of neighboring objects in a circle of radius 50 kpc.
The total number of individual SBS objects in the database is now 1676. The 188
Markarian galaxies which were re-discovered by SBS are not included in this
database. We also include redshifts that are now available for 1576 SBS
objects, as well as 2MASS infrared magnitudes for 1117 SBS galaxies.Comment: 13 pages, 1 figure, 1 tabl
Physical parameters and classification of eight galactic nuclei from the Second Byurakan Survey
Spectroscopic observations with a resolution of 4.5 Angst were performed for
a sample of eight galactic nuclei extracted from the Second Byurakan Survey,
and one companion galaxy of SBS 1204+505B. The EW and FWHM of the emission
lines were measured, and useful line ratios and diagnostic diagrams were used
for object classification and reddening estimates.
Intrinsic reddening quantities were calculated for all non QSO,i.e. seven
objects. Particularly the amount of reddening, BV color excess, extinction
coefficient and optical depths in the V band, at Halpha and Hbeta wavelengths,
and at 5100 Angst. The broad line region size was also estimated for seven
objects, as well as the central black hole masses. Three mass estimates were
usually performed for each object and compared. A peculiar line, probably He I
lambda 5048, is detected in the QSO SBS 1626+554. Evidence for a stratified
narrow line region is found for the two narrow line Seyfert 1 galaxies included
in the sample. A revised classification is proposed for two objects, and the
companion galaxy of SBS 1204+505B is reported as a nuclear starburst galaxy.Comment: To appear in PAS
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