34 research outputs found
Emission-Line Fluxes of Northern Planetary Nebulae
We present long slit spectrophotometric emission line fluxes of bright and
extended (<5 arcsec in diameter) Planetary Nebulae (PNe) selected from Acker et
al. 1992 catalog with suitable equitorial coordinates for Northern hemisphere.
In total, 17 PNe have been choosen and observed in 2008--2010. To measure
absolute fluxes, broad slit sizes, ranging from 3.5\arcsec to 7.5\arcsec were
used and thus equivalent widths of all observable emission line fluxes were
also calculated. Among 17 PNe's observed, line flux measurements of 12 of them
were made for the first time. This work also aims to extend the sky coverage of
emission line flux standards in Northern hemisphere (Dopita & Hua 1997 - 52 PNe
in Southern hemisphere; Wright et al. 2005 - 6 PNe in Northern hemisphere).
Electron temperatures and densities, and chemical abundances of these PNe were
also calculated in this work. These data is expected to lead the photometric or
spectrometric further work for absolute emission line flux measurements needed
for \hii regions, supernova remnants etc.Comment: 24 pages, 3 Figures, 21 Tables, Accepted for publication in
Publications of the Astronomical Society of Australi
Resolving the radio nebula around beta Lyrae
In this paper we present high spatial resolution radio images of the puzzling
binary system beta Lyrae obtained with MERLIN at 5 GHz. We find a nebula
surrounding the binary with a brightness temperature of 11000+-700K
approximately 40AU across. This definitively confirms the thermal origin of the
radio emission, which is consistent with emission from the wind of the B6-8II
component (mass loss of order of 10^-7 Msun per year), ionized by the radiation
field of the hotter companion. This nebula, surrounding the binary, is the
proof that beta Layrae evolved in a non-conservative way, i. e. not all the
mass lost by the primary is accretted by the secondary, and present
measurements indicate that almost 0.015Msun had been lost from the system since
the onset of the Roche lobe overflow phase. Moreover, the nebula is aligned
with the jet-like structures inferred from recent optical measurements,
indicating a possible connection among them.Comment: 5 pages, 2 figures. Accepted for publication in A&
A Case study of light pollution in France after the change in legislation
France issued a decree to restrict and prohibit mainly outdoor lighting
effective from January 1st, 2019. Effectiveness of this legislation has been
evaluated in this study using GIS data which was first used in
\cite{2020MNRAS.493.1204A} (so called astroGIS database - \url{astrogis.org}).
A subset of Artificial Light layer of astroGIS database has been adapted for
years between January 2012 and December 2019. During 2019, radiance of W cm sr has been released into space. Annual light
pollution in France decreased by 6\% after the enactment of artificial light
legislation. France continue to have potential Dark Sky Park locations for
example cities like Indre, Lot, Nievre and Creuse having the lowest light
pollution values. A strong correlation between population and light pollution
() has been observed. A similar but a weak correlation can also
be observed for GDP (). However, it is still too early to justify
whether the improvements observed in the dataset are due to the enactment of
the legislation or not.Comment: 10 pages, 4 figures, 2 tables, Submitted to Astrophysics and Space
Scienc
Global Site Selection for Astronomy
A global site selection for astronomy was performed with 1 km spatial
resolution ( 1 Giga pixel in size) using long term and up-to-date
datasets to classify the entire terrestrial surface on the Earth. Satellite
instruments are used to get the following datasets of Geographical Information
System (GIS) layers: Cloud Coverage, Digital Elevation Model, Artificial Light,
Precipitable Water Vapor, Aerosol Optical Depth, Wind Speed and Land Use --
Land Cover. A Multi Criteria Decision Analysis (MCDA) technique is applied to
these datasets creating four different series where each layer will have a
specific weight. We introduce for the first time a ``Suitability Index for
Astronomical Sites'' namely, SIAS. This index can be used to find suitable
locations and to compare different sites or observatories. Mid-western Andes in
South America and Tibetan Plateau in west China were found to be the best in
all SIAS Series. Considering all the series, less than 3 \% of all terrestrial
surfaces are found to be the best regions to establish an astronomical
observatory. In addition to this, only approximately 10 \% of all current
observatories are located in good locations in all SIAS series. Amateurs,
institutions or countries aiming to construct an observatory could create a
short-list of potential site locations using layout of SIAS values for each
country without spending time and budget.The outcomes and datasets of this
study has been made available through a web site, namely ``Astro GIS Database''
on \texttt{\url{www.astrogis.org}}.Comment: 19 Pages, 4 Figures, 7 tables, Accepted for publication in MNRA
Optical variabilities in Be/X-ray binary system:GRO J2058+42
We present an analysis of long-term optical monitoring observations and
optical spectroscopic observations of the counterpart to CXOU J205847.5+414637
(high mass X-ray binary system). We search for a variability in the light curve
of Be star. We used differential magnitudes in the time series analysis. The
variability search in the optical light curve was made by using different
algorithms. The reduction and analysis of spectra were done by using MIDAS and
its suitable packages. We have performed a frequency search which gave us the
value 2.404 1/day. This value is attributed to the non-radial pulsation of Be
star. H alpha emission line profiles always show double-peaked emissions with a
mean equivalent width of 2.31 \pm 0.19 \AA ~and a peak separation of 516 \pm 45
km/s. This suggests that Be star disk is still present. CXOU J205847.5+414637
is in X-ray quiescent state.Comment: 8 pages, 9 figures. To appear at Astronomy and Astrophysic
A Pipeline for the ROTSE-IIId Archival Data
We have constructed a new, fast, robust and reliable pipeline to detect
variable stars from the ROTSE-IIId archival data. Turkish share of ROTSE-III
archive contains approximately one million objects from a large field of view
(1.85\dgr) and it considerably covers a large portion of northern sky
(\delta>-25\dgr). The unfiltered ROTSE-III magnitude of the objects ranges
from 7.7 to 16.9. The main stages of the new pipeline are as follows: Source
extraction, astrometry of the objects, light curve generation and inhomogeneous
ensemble photometry. A high performance computing (HPC) algorithm has also been
implemented into the pipeline where we had a good performance even on a
personal computer. Running the algorithms of the pipeline on a cluster
decreases analysis time significantly from weeks to hours. The pipeline is
especially tested against long period variable stars with periods of a few
hundred days (e.g Mira and SR) and variables having periods starting from a few
days to a few hundred days were detected.Comment: 8 pages, 5 figures 2 tables; last revision before publishe
Neuroendocrine tumors presenting with thyroid gland metastasis: a case series
<p>Abstract</p> <p>Introduction</p> <p>Autopsy series have shown that metastasis to the thyroid gland has occurred in up to 24% of patients who have died of cancer. Neuroendocrine tumors may metastasize to thyroid gland.</p> <p>Case presentations</p> <p>Case 1 was a 17-year-old Turkish woman who was referred from our Endocrinology Department for a thyroidectomy for treatment of neuroendocrine tumor metastasis. She was treated with a bilateral total thyroidectomy. Histopathological examination results were consistent with a neuroendocrine tumor; neoplastic cells showed strong immunoreactivity to chromogranin A and synaptophysin, but the immunohistochemical profile was inconsistent with medullary thyroid carcinoma in that the tumor was negative for calcitonin, carcinoembryonic antigen, and thyroid transcription factor-1.</p> <p>Case 2 was a 54-year-old Turkish woman who presented with a 3-cm nodule on her right thyroid lobe. She had undergone surgery for a right lung mass four years previously. After a right pneumonectomy, thymectomy and lymph node dissection, a typical carcinoid tumor was diagnosed. Under ultrasonographic guidance, fine needle aspiration biopsy of her right thyroid pole nodule was performed and the biopsy was compatible with a neuroendocrine tumor metastasis. She was treated with a bilateral total thyroidectomy. Histopathological examination indicated three nodular lesions, 5 cm and 0.4 cm in diameter in her right lobe and 0.1 cm in diameter in her left lobe. The tumors were consistent with a neuroendocrine phenotype, showing strong immunoreactivity to chromogranin A and synaptophysin.</p> <p>Conclusion</p> <p>Thyroid nodules detected during follow-up of neuroendocrine tumor patients should be thoroughly investigated. A fine needle aspiration biopsy of the thyroid confirms the diagnosis in most cases and leads to appropriate management of those patients and may prevent unnecessary treatment approaches.</p