scholarly journals Wide-Field Observations of Variable Stars in the Region of NGC 7129

1994 ◽  
Vol 161 ◽  
pp. 475-477
Author(s):  
E.H. Semkov
Keyword(s):  
Variable Stars ◽  
Astronomical Observatory ◽  
Flare Star ◽  
Wide Field ◽  
Field Observations ◽  
Schmidt Telescope ◽  
Bulgarian Academy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Academy Of Sciences

During our programme for nonstable and flare star investigations in the star forming regions, more than 290 UBVR photographic plates in the field of the bright nebula NGC 7129 were obtained. The photographic observations were made with the 50/70/172 cm Schmidt telescope of the Rozhen Astronomical Observatory of the Bulgarian Academy of Sciences during the period September 1984–July 1993.

scholarly journals Catalogue of the Rozhen Observatory Schmidt Telescope

1994 ◽  
Vol 161 ◽  
pp. 377-379
Author(s):  
A. Mutafov ◽  
P. Ilcheva ◽  
M. Kusheva ◽  
M. Michailov ◽  
Z. Borisov ◽  
...  
Keyword(s):  
Astronomical Observatory ◽  
Schmidt Telescope ◽  
Bulgarian Academy ◽  
Machine Readable ◽  
Academy Of Sciences

We present the results from the analysis of the machine-readable version of the log book for the 50/70 cm Schmidt telescope of the National Astronomical Observatory (NAO) Rozhen of the Bulgarian Academy of Sciences. The telescope began operating in 1979, after it was repaired and transferred from the Potsdam Observatory where it had operated since 1952.

scholarly journals The 50/70-Cm Schmidt Telescope At The Bulgarian National Asthonomical Observatory

1984 ◽  
Vol 78 ◽  
pp. 207-209
Author(s):  
Milcho K. Tsvetkov
Keyword(s):  
Astronomical Observatory ◽  
Radius Of Curvature ◽  
Schmidt Telescope ◽  
Bulgarian Academy ◽  
Term Operation ◽  
Main Mirror ◽  
Academy Of Sciences ◽  
Mutual Agreement

The 50/70 Schmidt telescope at the National Astronomical Observatory (NAO), Bulgarian Academy of Sciences, is an example of the possibilities for a long-term operation and everlasting actuality of these types of telescopes. Originally, this telescope was constructed in the GDR in 1952 and mounted in the Potsdam Observatory, Academy of Sciences of the GDR (as such, it is on the list of West, 1974). In 1979, on the basis of a mutual agreement between the Bulgarian Academy of Sciences and the Academy of Sciences of the GDR, it was transferred to Rozhen, Bulgaria. The principal parameters of the instrument are as follows: I. Main mirror: diameter: 70cm; material: Tempax; thickness in the centre: 10 cm; radius of curvature: 344 cm.

scholarly journals A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) – III. Exploring the properties of young associations through their variables, dippers, and candidate exoplanets

2020 ◽  
Vol 498 (4) ◽  
pp. 5972-5989
Author(s):  
D Nardiello
Keyword(s):  
Variable Stars ◽  
Open Clusters ◽  
Light Curves ◽  
Quality Data ◽  
Stellar Systems ◽  
Satellite Mission ◽  
Open Clusters And Associations ◽  
Star Forming ◽  
Star Forming Regions ◽  
Strong Candidate

ABSTRACT Young associations in star-forming regions are stellar systems that allow us to understand the mechanisms that characterize the stars in their early life and what happens around them. In particular, the analysis of the discs and of the exoplanets around young stars allows us to know the key processes that prevail in their evolution and understand the properties of the exoplanets orbiting older stars. The Transiting Exoplanet Survey Satellite mission is giving us the opportunity to extract and analyse the light curves of association members with high accuracy, but the crowding that affects these regions makes difficult the light curve extraction. In the PATHOS project, cutting-edge tools are used to extract high-precision light curves and identify variable stars and transiting exoplanets in open clusters and associations. In this work, I analysed the light curves of stars in five young (≲10 Myr) associations, searching for variables and candidate exoplanets. Using the rotational periods of the association members, I constrained the ages of the five stellar systems (∼2–10 Myr). I searched for dippers, and I investigated the properties of the dust that forms the circumstellar discs. Finally, I searched for transiting signals, finding six strong candidate exoplanets. No candidates with radius RP ≲ 0.9 RJ have been detected, in agreement with the expectations. The frequency of giant planets resulted to be ∼2–3 per cent, higher than that expected for field stars (≲ 1 per cent); the low statistic makes this conclusion not strong, and new investigations on young objects are mandatory to confirm this result.

scholarly journals Statistical Studies of Supernova Environments

2015 ◽  
Vol 32 ◽  
Author(s):  
Joseph P. Anderson ◽  
Phil A. James ◽  
Stacey M. Habergham ◽  
Lluís Galbany ◽  
Hanindyo Kuncarayakti
Keyword(s):  
Stellar Evolution ◽  
Meta Analysis ◽  
Mass Range ◽  
Host Galaxy ◽  
Core Collapse ◽  
Wide Field ◽  
Star Forming ◽  
Star Forming Regions ◽  
Hα Emission ◽  
Field Unit

AbstractMapping the diversity of SNe to progenitor properties is key to our understanding of stellar evolution and explosive stellar death. Investigations of the immediate environments of SNe allow statistical constraints to be made on progenitor properties such as mass and metallicity. Here, we review the progress that has been made in this field. Pixel statistics using tracers of e.g. star formation within galaxies show intriguing differences in the explosion sites of, in particular SNe types II and Ibc (SNe II and SNe Ibc respectively), suggesting statistical differences in population ages. Of particular interest is that SNe Ic are significantly more associated with host galaxy Hα emission than SNe Ib, implying shorter lifetimes for the former. In addition, such studies have shown (unexpectedly) that the interacting SNe IIn do not explode in regions containing the most massive stars, which suggests that at least a significant fraction of their progenitors arise from the lower end of the core-collapse SN mass range. Host H ii region spectroscopy has been obtained for a significant number of core-collapse events, however definitive conclusions on differences between distinct SN types have to-date been elusive. Single stellar evolution models predict that the relative fraction of SNe Ibc to SNe II should increase with increasing metallicity, due to the dependence of mass-loss rates on progenitor metallicity. We present a meta-analysis of all current host H ii region oxygen abundances for CC SNe. It is concluded that the SN II to SN Ibc ratio shows little variation with oxygen abundance, with only a suggestion that the ratio increases in the lowest bin. Radial distributions of different SNe are discussed, where a central excess of SNe Ibc has been observed within disturbed galaxy systems, which is difficult to ascribe to metallicity or selection effects. Environment studies are also being undertaken for SNe Ia, where constraints can be made on the shortest delay times of progenitor systems. It is shown that ‘redder’ SNe Ia are more often found within star-forming regions. Environment studies are evolving to enable studies at higher spatial resolutions than previously possible, while in addition the advent of wide-field integral field unit instruments allows galaxy-wide spectral analyses which will provide fruitful results to this field. Some example contemporary results are shown in that direction.

scholarly journals SK 1: A possible case of triggered star formation in perseus

2006 ◽  
Vol 2 (S237) ◽  
pp. 217-221
Author(s):  
Miriam Rengel ◽  
Klaus Hodapp ◽  
Jochen Eislöffel
Keyword(s):  
Star Formation ◽  
Molecular Clouds ◽  
Thermal Emission ◽  
Young Stellar Objects ◽  
Wide Field ◽  
Dust Shell ◽  
Stellar Objects ◽  
Star Forming ◽  
Star Forming Regions ◽  
Suitable Target

AbstractAccording to a triggered star formation scenario (e.g. Martin-Pintado & Cernicharo 1987) outflows powered by young stellar objects shape the molecular clouds, can dig cavities, and trigger new star formation. NGC 1333 is an active site of low- and intermediate star formation in Perseus and is a suggested site of self-regulated star formation (Norman & Silk 1980). Therefore it is a suitable target for a study of triggered star formation (e.g. Sandell & Knee 2001, SK1). On the other hand, continuum sub-mm observations of star forming regions can detect dust thermal emission of embedded sources (which drive outflows), and further detailed structures.Within the framework of our wide-field mapping of star formation regions in the Perseus and Orion molecular clouds using SCUBA at 850 and 450 μm, we mapped NCG 1333 with an area of around 14′× 21′. The maps show more structure than the previous maps of the region observed in sub-mm. We have unveiled the known embedded SK 1 source (in the dust shell of the SSV 13 ridge) and detailed structure of the region, among some other young protostars.In agreement with the SK 1 observations, our map of the region shows lumpy filaments and shells/cavities that seem to be created by outflows. The measured mass of SK 1 (~0.07 M) is much less than its virial mass (~0.2-1 M). Our observations support the idea of SK 1 as an event triggered by outflow-driven shells in NGC 1333 (induced by an increase in gas pressure and density due to radiation pressure from the stellar winds that have presumably created the dust shell). This kind of evidences provides a more thorough understanding of the star formation regulation processes.

scholarly journals 22 GHz Water Maser Survey of the Xinjiang Astronomical Observatory

2012 ◽  
Vol 8 (S287) ◽  
pp. 296-297
Author(s):  
Jian-jun Zhou ◽  
Jarken Esimbek ◽  
Gang Wu
Keyword(s):  
Galactic Plane ◽  
Astronomical Observatory ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Gas Kinematics ◽  
Star Forming Regions ◽  
Water Masers ◽  
Maser Sources ◽  
Water Maser

AbstractWater masers are good tracers of high-mass star-forming regions. Water maser VLBI observations provide a good probe for studying high-mass star formation and galactic structure. We plan to make a blind survey toward the northern Galactic plane in future years using the 25 m radio telescope of the Xinjiang Astronomical Observatory. We will select some water maser sources discovered in the survey and perform high resolution observations to study the gas kinematics close to high-mass protostars.

scholarly journals Magnetic fields in massive star forming regions: wide-field NIR polarimetry of M42 and Mon R2

2008 ◽  
Vol 4 (S259) ◽  
pp. 97-98 ◽  
Author(s):  
Nobuhiko Kusakabe ◽  
Motohide Tamura ◽  
Ryo Kandori ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Massive Star ◽  
Near Infrared ◽  
Polarized Light ◽  
Field Structure ◽  
Wide Field ◽  
Magnetic Field Structure ◽  
Star Forming ◽  
Star Forming Regions

AbstractMagnetic fields are believed to play an important role in star formation. We observed M42 and Mon R2 massive star forming regions using the wide-field (8′ × 8′) near-infrared imaging polarimeter SIRPOL in South Africa. Magnetic fields are mapped on the basis of dichroic polarized light from hundreds of young stars embedded in the regions. We found “hourglass shaped” magnetic field structure toward OMC-1 region, which is very consistent with magnetic fields traced by using dust emission polarimetry at sub-mm to FIR wavelengths. In the Mon R2 region, we found “S-shaped” magnetic field structure across the massive protostar IRS 1 and IRS 2. We will present the results of comparison of magnetic fields at NIR with those at other wavelengths.

scholarly journals On the Applicability of Fibre-Fed Multi-Object Spectrographs in Flare Star Research

1995 ◽  
Vol 148 ◽  
pp. 85-89
Author(s):  
Gábor Szécsényi-Nagy
Keyword(s):  
Near Infrared ◽  
Focal Length ◽  
Open Cluster ◽  
Variable Stars ◽  
Open Clusters ◽  
Flare Star ◽  
Spectral Studies ◽  
Wide Field ◽  
New Device ◽  
Flare Stars

AbstractThe use of optical fibres has recently allowed the full field of some Schmidt telescopes to be accessed for multi-object spectroscopy. The new device: the MOS (multi-object spectrograph) is to revolutionize the field of astronomical spectroscopy. Cosmic objects grouped into aggregates having apparent angular diameters of 1 to 6 degrees and similar apparent brightness in the visual or near infrared spectral range are to be the most probable future targets of MOSs. Flare stars — as it has been demonstrated convincingly by various authors (see Szecsenyi-Nagy 1986, and references therein) — are the most abundant type of variable stars but because of their low luminosity and relatively late discovery we have only very limited amount of spectroscopic data about most of these objects. It is a real bonanza that most of the catalogued flare stars are associated with young open clusters and this fact of course suggests them as really promising targets for wide-field Schmidt cameras equipped with MOSs. In an average open cluster scrutinized for its flare star members some dozen or some hundred representatives of this species are known which are distributed over a sky field of 10–20 square degrees. Fortunately, they are never packed into unresolvable concentrations and even short focal length cameras are able to produce separate images of all cluster member flare stars for an accurate photographic photometry of the objects. The apparent visual brightness of these stars most often fits a 5–7 magnitude range. This seems to be profitable also for the effectiveness of using fibre-fed MOSs in flare star spectroscopy. The first steps of such a program should be the study of radial velocities and the comparison of the measured values with the accepted radial velocity of the cluster. These measurements could provide new and independent arguments for (or against?) the cluster membership of the flare stars observed in the fields of catalogued open clusters. Later, more detailed spectral studies should collect information about the time dependent features of the spectra of flare stars.

scholarly journals Beauty and Astrophysics

2000 ◽  
Vol 17 (2) ◽  
pp. 179-184 ◽  
Author(s):  
Michael S. Bessell
Keyword(s):  
Milky Way ◽  
Galactic Plane ◽  
Narrow Band ◽  
Public Awareness ◽  
Broad Band ◽  
Wide Field ◽  
Single Exposure ◽  
Star Forming ◽  
Star Forming Regions ◽  
Telephoto Lens

AbstractSpectacular colour images have been made by combining CCD images in three different passbands using Adobe Photoshop. These beautiful images highlight a variety of astrophysical phenomena and should be a valuable resource for science education and public awareness of science. The wide field images were obtained at the Siding Spring Observatory (SSO) by mounting a Hasselblad or Nikkor telephoto lens in front of a 2K × 2K CCD. Options of more than 30 degrees or 6 degrees square coverage are produced in a single exposure in this way. Narrow band or broad band filters were placed between lens and CCD enabling deep, linear images in a variety of passbands to be obtained. We have mapped the LMC and SMC and are mapping the Galactic Plane for comparison with the Molonglo Radio Survey. Higher resolution images have also been made with the 40 inch telescope of galaxies and star forming regions in the Milky Way.

Detection of AGB stars in the IC 10 dwarf irregular galaxy

2018 ◽  
Vol 14 (S344) ◽  
pp. 70-72
Author(s):  
Mahtab Gholami ◽  
Atefeh Javadi ◽  
Jacco Th. van Loon ◽  
Habib Khosroshahi ◽  
Mohammad Taghi Mirtorabi ◽  
...  
Keyword(s):  
Dwarf Galaxies ◽  
Big Bang ◽  
Variable Stars ◽  
Asymptotic Giant Branch ◽  
Star Formation History ◽  
Wide Field ◽  
Asymptotic Giant Branch Stars ◽  
Star Forming ◽  
Isaac Newton ◽  
Ic 10

AbstractAmongst the dwarf galaxies in the Local Group, the isolated irregular one, IC 10 is one of the most interesting galaxies, with strong star forming activity and the highest density of Wolf-Rayet stars. Undergoing a starburst phase, having numerous HII regions and being bright in all wavebands, makes it an exquisite galaxy to study the internal and external processes that continue to affect dwarf galaxies 14 Gyr since the Big Bang. In this study, we present a new deep and precise optical monitoring survey of IC 10 using the Isaac Newton Telescope (INT) with the wide field camera (WFC). We performed observations at nine epochs spaced between three to four months apart between 2015 and 2017. We identified Long Period Variable stars (LPVs), Asymptotic Giant Branch stars (AGBs) and Red Super Giant stars (RSGs) to determine the star formation history and chemical evolution of IC 10.

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