60 research outputs found
Pornography and erotica: Definitions and Prevalence
In this paper, we offer some observations regarding the sex industry, in particular the pornography and erotica sectors. Marketing literature observing pornography and erotica is scant. We find that following exponential growth of the sex industry (given use of the Internet) an evaluation of consumer behaviour and marketing practices is justified. In order to begin a study of these industry sectors, we find it necessary to define both pornography and erotica. Following the development of definitions, we consider these industries from a marketing perspective in the hope that we may encourage research into these areas
Nothing to hide: An X-ray survey for young stellar objects in the Pipe Nebula
We have previously analyzed sensitive mid-infrared observations to establish
that the Pipe Nebula has a very low star-formation efficiency. That study
focused on YSOs with excess infrared emission (i.e, protostars and pre-main
sequence stars with disks), however, and could have missed a population of more
evolved pre-main sequence stars or Class III objects (i.e., young stars with
dissipated disks that no longer show excess infrared emission). Evolved
pre-main sequence stars are X-ray bright, so we have used ROSAT All-Sky Survey
data to search for diskless pre-main sequence stars throughout the Pipe Nebula.
We have also analyzed archival XMM-Newton observations of three prominent areas
within the Pipe: Barnard 59, containing a known cluster of young stellar
objects; Barnard 68, a dense core that has yet to form stars; and the Pipe
molecular ring, a high-extinction region in the bowl of the Pipe. We
additionally characterize the X-ray properties of YSOs in Barnard 59. The ROSAT
and XMM-Newton data provide no indication of a significant population of more
evolved pre-main sequence stars within the Pipe, reinforcing our previous
measurement of the Pipe's very low star formation efficiency.Comment: Accepted for publication in Ap
Cataclysmic Variables from SDSS II. The Second Year
The first full year of operation following the commissioning year of the
Sloan Digital Sky Survey has revealed a wide variety of newly discovered
cataclysmic variables. We show the SDSS spectra of forty-two cataclysmic
variables observed in 2002, of which thirty-five are new classifications, four
are known dwarf novae (CT Hya, RZ Leo, T Leo and BZ UMa), one is a known CV
identified from a previous quasar survey (Aqr1) and two are known ROSAT or
FIRST discovered CVs (RX J09445+0357, FIRST J102347.6+003841). The SDSS
positions, colors and spectra of all forty-two systems are presented. In
addition, the results of follow-up studies of several of these objects identify
the orbital periods, velocity curves and polarization that provide the system
geometry and accretion properties. While most of the SDSS discovered systems
are faint (>18th mag) with low accretion rates (as implied from their spectral
characteristics), there are also a few bright objects which may have escaped
previous surveys due to changes in the mass transfer rate.Comment: Accepted for publication in The Astronomical Journal, Vol. 126, Sep.
2003, 44 pages, 25 figures (now with adjacent captions), AASTeX v5.
Do Moderate-Luminosity Active Galactic Nuclei Suppress Star Formation?
The growth of supermassive black holes and their host galaxies are thought to
be linked, but the precise nature of this symbiotic relationship is still
poorly understood. Both observations and simulations of galaxy formation
suggest that the energy input from active galactic nuclei (AGN), as the central
supermassive black hole accretes material and grows, heats the interstellar
material and suppresses star formation. In this Letter, we show that most host
galaxies of moderate-luminosity supermassive black holes in the local universe
have intermediate optical colors that imply the host galaxies are transitioning
from star formation to quiescence, the first time this has been shown to be
true for all AGN independent of obscuration. The intermediate colors suggest
that star formation in the host galaxies ceased roughly 100 Myr ago. This
result indicates that either the AGN are very long-lived, accreting for more
than 1 Gyr beyond the end of star formation, or there is a ~100 Myr time delay
between the shutdown of star formation and detectable black hole growth. The
first explanation is unlikely given current estimates for AGN lifetimes, so
low-lumiosity AGN must shut down star formation before substantial black hole
accretion activity is detected. The scarcity of AGN host galaxies in the blue
cloud reported here challenges scenarios where significant star formation and
black hole growth are coeval. Lastly, these observations also strongly support
the `Unified Model' of AGN as the host galaxy colors are independent of
obscuration towards the central engine.Comment: Accepted for publication in ApJ Letters. 7 pages, 4 figure
Two Rare Magnetic Cataclysmic Variables with Extreme Cyclotron Features Identified in the Sloan Digital Sky Survey
Two newly identified magnetic cataclysmic variables discovered in the Sloan
Digital Sky Survey (SDSS), SDSSJ155331.12+551614.5 and SDSSJ132411.57+032050.5,
have spectra showing highly prominent, narrow, strongly polarized cyclotron
humps with amplitudes that vary on orbital periods of 4.39 and 2.6 hrs,
respectively. In the former, the spacing of the humps indicates the 3rd and 4th
harmonics in a magnetic field of ~60 MG. The narrowness of the cyclotron
features and the lack of strong emission lines imply very low temperature
plasmas and very low accretion rates, so that the accreting area is heated by
particle collisions rather than accretion shocks. The detection of rare systems
like these exemplifies the ability of the SDSS to find the lowest accretion
rate close binaries.Comment: Accepted for publication in the Astrophysical Journal, vol. 583,
February 1, 2003; slight revisions and additions in response to referee's
comments; 17 pages, 6 figures, AASTeX v4.
Photometric Observations of Three High Mass X-Ray Binaries and a Search for Variations Induced by Orbital Motion
We searched for long period variation in V-band, Ic-band and RXTE X-ray light
curves of the High Mass X-ray Binaries (HMXBs) LS 1698 / RX J1037.5-5647, HD
110432 / 1H 1249-637 and HD 161103 / RX J1744.7-2713 in an attempt to discover
orbitally induced variation. Data were obtained primarily from the ASAS
database and were supplemented by shorter term observations made with the 24-
and 40-inch ANU telescopes and one of the robotic PROMPT telescopes. Fourier
periodograms suggested the existence of long period variation in the V-band
light curves of all three HMXBs, however folding the data at those periods did
not reveal convincing periodic variation. At this point we cannot rule out the
existence of long term V-band variation for these three sources and hints of
longer term variation may be seen in the higher precision PROMPT data. Long
term V-band observations, on the order of several years, taken at a frequency
of at least once per week and with a precision of 0.01 mag, therefore still
have a chance of revealing long term variation in these three HMXBs.Comment: Accepted, RAA, May, 201
X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey
The ROSAT All-Sky Survey (RASS) was the first imaging X-ray survey of the
entire sky. While X-ray source counterparts are known to range from distant
quasars to nearby M dwarfs, the RASS data alone are often insufficient to
determine the nature of an X-ray source. As a result, large-scale follow-up
programs are required to construct samples of known X-ray emitters. We use
optical data produced by the Sloan Digital Sky Survey (SDSS) to identify 709
stellar X-ray emitters cataloged in the RASS and falling within the SDSS Data
Release 1 footprint. Most of these are bright stars with coronal X-ray emission
unsuitable for SDSS spectroscopy, which is designed for fainter objects (g > 15
mag). Instead, we use SDSS photometry, correlations with the Two Micron All Sky
Survey and other catalogs, and spectroscopy from the Apache Point Observatory
3.5 m telescope to identify these stellar X-ray counterparts. Our sample of 707
X-ray-emitting F, G, K, and M stars is one of the largest X-ray-selected
samples of such stars. We derive distances to these stars using photometric
parallax relations appropriate for dwarfs on the main sequence, and use these
distances to calculate LX. We also identify a previously unknown cataclysmic
variable (CV) as a RASS counterpart. Separately, we use correlations of the
RASS and the SDSS spectroscopic catalogs of CVs and white dwarfs (WDs) to study
the properties of these rarer X-ray-emitting stars. We examine the relationship
between (fX/fg) and the equivalent width of the Hbeta emission line for 46
X-ray-emitting CVs and discuss tentative classifications for a subset based on
these quantities. We identify 17 new X-ray-emitting DA (hydrogen) WDs, of which
three are newly identified WDs. (abridged)Comment: 23 pages, 15 figures, 8 tables; full catalog available online onl
PTF10nvg: An Outbursting Class I Protostar in the Pelican/North American Nebula
During a synoptic survey of the North American Nebula region, the Palomar
Transient Factory (PTF) detected an optical outburst (dubbed PTF10nvg)
associated with the previously unstudied flat or rising spectrum infrared
source IRAS 20496+4354. The PTF R-band light curve reveals that PTF10nvg
brightened by more than 5 mag during the current outburst, rising to a peak
magnitude of R~13.5 in 2010 Sep. Follow-up observations indicate PTF10nvg has
undergone a similar ~5 mag brightening in the K band, and possesses a rich
emission-line spectrum, including numerous lines commonly assumed to trace mass
accretion and outflows. Many of these lines are blueshifted by ~175 km/s from
the North American Nebula's rest velocity, suggesting that PTF10nvg is driving
an outflow. Optical spectra of PTF10nvg show several TiO/VO bandheads fully in
emission, indicating the presence of an unusual amount of dense (> 10^10
cm^-3), warm (1500-4000 K) circumstellar material. Near-infrared spectra of
PTF10nvg appear quite similar to a spectrum of McNeil's Nebula/V1647 Ori, a
young star which has undergone several brightenings in recent decades, and
06297+1021W, a Class I protostar with a similarly rich near--infrared emission
line spectrum. While further monitoring is required to fully understand this
event, we conclude that the brightening of PTF10nvg is indicative of enhanced
accretion and outflow in this Class-I-type protostellar object, similar to the
behavior of V1647 Ori in 2004-2005.Comment: Accepted to the Astronomical Journal; 21 pages, 11 figures, 6 tables
in emulateapj format; v2 fixes typo in abstract; v3 updates status to
accepted, adjusts affiliations, adds acknowledgmen
Galaxy Zoo: Passive Red Spirals
We study the spectroscopic properties and environments of red spiral galaxies
found by the Galaxy Zoo project. By carefully selecting face-on, disk dominated
spirals we construct a sample of truly passive disks (not dust reddened, nor
dominated by old stellar populations in a bulge). As such, our red spirals
represent an interesting set of possible transition objects between normal blue
spirals and red early types. We use SDSS data to investigate the physical
processes which could have turned these objects red without disturbing their
morphology. Red spirals prefer intermediate density regimes, however there are
no obvious correlations between red spiral properties and environment -
environment alone is not sufficient to determine if a spiral will become red.
Red spirals are a small fraction of spirals at low masses, but are a
significant fraction at large stellar masses - massive galaxies are red
independent of morphology. We confirm that red spirals have older stellar popns
and less recent star formation than the main spiral population. While the
presence of spiral arms suggests that major star formation cannot have ceased
long ago, we show that these are not recent post-starbursts, so star formation
must have ceased gradually. Intriguingly, red spirals are ~4 times more likely
than normal spirals to host optically identified Seyfert or LINER, with most of
the difference coming from LINERs. We find a curiously large bar fraction in
the red spirals suggesting that the cessation of star formation and bar
instabilities are strongly correlated. We conclude by discussing the possible
origins. We suggest they may represent the very oldest spiral galaxies which
have already used up their reserves of gas - probably aided by strangulation,
and perhaps bar instabilities moving material around in the disk.Comment: MNRAS in press, 20 pages, 15 figures (v3
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