scholarly journals Long-term optical photometric monitoring of the FUor star V900 Mon

2021 ◽  
pp. 31-38
Author(s):  
E.H. Semkov ◽  
S.P. Peneva ◽  
S.I. Ibryamov
Keyword(s):  
Stellar Evolution ◽  
Stellar Magnitude ◽  
Photometric Data ◽  
Light Curves ◽  
Pass Band ◽  
Archival Data ◽  
Space Telescopes ◽  
History Of ◽  
Photometric Monitoring

We present results from photometric monitoring of V900 Mon, one of the newly discovered and still under-studied object from the FU Orionis type. The FUor phenomenon is very rarely observed, but it is essential for stellar evolution. Since we only know about twenty stars of this type, the study of each new object is very important for our knowledge. Our data were obtained in optical spectral region with the BVRI Johnson-Cousins set of filters during the period from September 2011 to April 2021. In order to follow the photometric history of the object, we measured its stellar magnitudes on available plates from the Mikulski Archive for Space Telescopes. The collected archival data suggest that the rise in brightness of V900 Mon began after January 1989 and the outburst goes on so far. In November 2009, when the outburst was registered, the star had already reached the level of brightness close to the current one. Our observations indicate that during the period 2011-2017 the stellar magnitude increased gradually in each pass band. The observed amplitude of the outburst is about 4 magnitudes (R). During the last three years, the increase in brightness has stopped and there has even been a slight decline. The comparison of light curves of the known FUor objects shows that they are very diverse and are rarely repeated. However, the photometric data we have so far show that V900 Mon's light curve is somewhat similar to those of V1515 Cyg and V733 Cep.

scholarly journals Long-term Photometric Monitoring of FUor and FUor-like Objects

2018 ◽  
pp. 240-248
Author(s):  
E. Semkov ◽  
S. Ibryamov ◽  
S. Peneva ◽  
A. Mutafov
Keyword(s):  
Light Curve ◽  
Significant Role ◽  
Stellar Evolution ◽  
Photographic Plate ◽  
Light Curves ◽  
Curve Shape ◽  
Rate Of Increase ◽  
Fu Ori ◽  
Photometric Monitoring

A phenomenon with a significant role in stellar evolution is the FU Orionis (FUor) type of outburst. The first three (classical) FUors (FU Ori, V1515 Cyg and V1057 Cyg) are well-studied and their light curves are published in the literature. But recently, over a dozen new objects of this type were discovered, whose photometric history we do not know well. Using recent data from photometric monitoring and data from the photographic plate archives we aim to study, the long-term photometric behavior of FUor and FUor-like objects. The construction of the historical light curves of FUors could be very important for determining the beginning of the outburst, the time to reach the maximum light, the rate of increase and decrease in brightness, the pre-outburst variability of the star. So far we have published our results for the light curves of V2493 Cyg, V582 Aur, Parsamian 21 and V1647 Ori. In this paper we present new data that describe more accurate the photometric behavior of these objects. In comparing our results with light curves of the well-studied FUors (FU Ori, V1515 Cyg and V1057 Cyg), we conclude that every object shows different photometric behavior. Each known FUor has a different rate of increase and decrease in brightness and a different light curve shape.

scholarly journals Photometric Monitoring of Binaries in Open Clusters and Associations: NGC 6231

2004 ◽  
Vol 194 ◽  
pp. 79-80
Author(s):  
C. Sterken ◽  
M. Y. Bouzid
Keyword(s):  
Open Clusters ◽  
Light Curves ◽  
Open Clusters And Associations ◽  
Pulsating Stars ◽  
Compact Binaries ◽  
Photometric Monitoring ◽  
Variable Light

AbstractOver the last couple of years we carried out long-term CCD monitoring of open clusters and associations with as principal goal the detection and study of pulsating stars. A by-product of this project is the serendipitous collection of multicolour photometry of most interesting compact binaries which show signs of activity, viz. variable periods and strongly variable light curves. This presentation illustrates the project, and concentrates on intriguing species of interacting binaries in NGC 6231.

scholarly journals Eclipsing Binaries Within Visual Ones: Prospects of Combined Solution

2011 ◽  
Vol 7 (S282) ◽  
pp. 207-208
Author(s):  
Petr Zasche
Keyword(s):  
Orbital Motion ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Period Variation ◽  
Mass Determination ◽  
Multiple Systems ◽  
Mutual Inclination ◽  
Combined Solution ◽  
Photometric Monitoring

AbstractThe study of eclipsing binaries as members of multiple systems can provide us important information about their origin, evolution, mutual inclination of the orbits, independent distance and mass determination, as well as the stellar multiplicity in general. We are carrying out a long-term photometric monitoring of several eclipsing binaries within the visual multiples and, besides the complete light curves, we are trying to detect the period changes due to the orbital motion around a common barycenter.Systems like DN UMa, V819 Her, LO Hya, or VW Cep are typical examples of eclipsing binaries orbiting around the barycenter of the multiple system, while their respective periods are on the order of years or decades. However, the expected period variation is only hardly detectable and there is still uncertainty about which of the components is the eclipsing one. Precise spectroscopy would be of great benefit, but detecting the changes in the gamma velocity is still problematic, and spectral disentangling of such complicated systems like sextuple VV Crv (periods 1.46, 3.14, and 44.51 days) is also rather difficult. However, the detection of the changing depths of the eclipses in the latter system would be interesting.

scholarly journals 30 Years of Multifrequency Quasar Variability: A Personal Journey

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 69
Author(s):  
James R. Webb
Keyword(s):  
Gamma Rays ◽  
Point Of View ◽  
Light Curves ◽  
X Rays ◽  
Optical Monitoring ◽  
Frequency Spectra ◽  
History Of ◽  
Quasar Variability ◽  
Term Monitoring

I outline the history of and progress in observing and understanding quasar multi-frequency and multi-messenger variability from the point of view of someone who has been working in the field for over 30 years. I will present some important references for the evolution from optical monitoring to multi-frequency cooperative programs that revealed the true multi-frequency/multi-timescale nature of variability in these objects. Quasar observations began with separate radio and optical monitoring programs; then the optical and radio observations w ere combined. This was followed by expanding the analyses to include far IR, UV, X-rays, and finally adding gamma rays. This progression yielded simultaneous multi-frequency spectra of these objects and light curves over 15 decades in frequency. The future is adding particle (neutrino) and gravitational waves to the picture. I also present long-term (50 years) optical light curves, and discuss optical variability at all timescales from minutes to tens of years in some selected objects for which we have reliable long-term monitoring observations.

scholarly journals Long-term Photometric Monitoring of Cool Hydrogen-deficient Carbon Stars

1995 ◽  
Vol 155 ◽  
pp. 431-432
Author(s):  
P.L. Cottrell ◽  
A.C. Gilmore ◽  
P.M. Kilmartin ◽  
W.A. Lawson
Keyword(s):  
Large Amplitude ◽  
Stellar Atmospheres ◽  
Light Curves ◽  
Maximum Light ◽  
Stellar Nucleosynthesis ◽  
Grain Formation ◽  
The Galaxy ◽  
Photometric Monitoring ◽  
Low Amplitude

Interest in the hydrogen-deficient carbon (HdC) stars, and the R Coronae Borealis (RCB) stars in particular, has been rekindled by the realisation that these stars provide the potential for testing models in a number of areas. These include: pulsation theory; grain formation; grain evolution; stellar nucleosynthesis and extended stellar atmospheres.Observational work on these objects has increased dramatically over the last 10 years. This has included both spectroscopic and photometric projects, see Lambert & Rao (1994) and Lawson et al. (1990).We have continued to observe a number of the cool HdC stars in the Galaxy and the LMC and now have light curves exceeding 2000 days in duration for many of these objects. In particular, we are observing the RCB stars to investigate both the low amplitude, pulsation-related variations present at maximum light and the photometric behaviour during the large amplitude declines.

scholarly journals OAO-2 Observations of Beta Lyrae and a Provisional Interpretation

1971 ◽  
Vol 15 ◽  
pp. 308-313 ◽  
Author(s):  
Yoji Kondo ◽  
George E. McCluskey ◽  
Ted E. Houck
Keyword(s):  
Photometric Data ◽  
Light Curves ◽  
Spectroscopic Information ◽  
Orbital Revolution ◽  
Short And Long Term ◽  
Photoelectric Observations ◽  
Long Term Variations

AbstractSix-color ultraviolet photoelectric observations of Beta Lyrae obtained with OAO-2 are presented. These observations, made at 1380 Ǡ, 1500 Ǡ, 1920 Ǡ, 2460 Ǡ, 2980 Ǡ, and 3330 Ǡ, represent the first truly continual coverage of the light changes of Beta Lyrae during one orbital revolution and were obtained in November 1970. The photometric data are supplemented by spectral scans in the wavelength intervals 3800 Ǡ to 1800 Ǡ and 2000 Ǡ to 1050 Ǡ; the latter interval was scanned at 10 Ǡ resolution once during every OAO-2 orbit, i. e., about 100 minutes. Anomalous features, such as asymmetries and short and long term variations, are present in the light curves. A tentative discussion of solutions of the light curves is given. The problems of combining the photometric and spectroscopic information to arrive at a model of the system are also discussed.

scholarly journals Ground-based optical transmission spectrum of the hot Jupiter HAT-P-1b

2019 ◽  
Vol 631 ◽  
pp. A169 ◽  
Author(s):  
Kamen O. Todorov ◽  
Jean-Michel Désert ◽  
Catherine M. Huitson ◽  
Jacob L. Bean ◽  
Vatsal Panwar ◽  
...  
Keyword(s):  
Time Series ◽  
Optical Transmission ◽  
Light Curves ◽  
Photometric Variability ◽  
Systematic Effects ◽  
Photometric Monitoring ◽  
Sufficient Precision ◽  
Resonance Absorption Line ◽  
Hot Jupiter

Context. Time-series spectrophotometric studies of exoplanets during transit using ground-based facilities are a promising approach to characterize their atmospheric compositions. Aims. We aim to investigate the transit spectrum of the hot Jupiter HAT-P-1b. We compare our results to those obtained at similar wavelengths by previous space-based observations. Methods. We observed two transits of HAT-P-1b with the Gemini Multi-Object Spectrograph (GMOS) instrument on the Gemini North telescope using two instrument modes covering the 320–800 and 520–950 nm wavelength ranges. We used time-series spectrophotometry to construct transit light curves in individual wavelength bins and measure the transit depths in each bin. We accounted for systematic effects. We addressed potential photometric variability due to magnetic spots in the planet’s host star with long-term photometric monitoring. Results. We find that the resulting transit spectrum is consistent with previous Hubble Space Telescope (HST) observations. We compare our observations to transit spectroscopy models that marginally favor a clear atmosphere. However, the observations are also consistent with a flat spectrum, indicating high-altitude clouds. We do not detect the Na resonance absorption line (589 nm), and our observations do not have sufficient precision to study the resonance line of K at 770 nm. Conclusions. We show that even a single Gemini/GMOS transit can provide constraining power on the properties of the atmosphere of HAT-P-1b to a level comparable to that of HST transit studies in the optical when the observing conditions and target and reference star combination are suitable. Our 520–950 nm observations reach a precision comparable to that of HST transit spectra in a similar wavelength range of the same hot Jupiter, HAT-P-1b. However, our GMOS transit between 320–800 nm suffers from strong systematic effects and yields larger uncertainties.

scholarly journals Optical light curves of FUor and FUor-like objects

2016 ◽  
Vol 12 (S325) ◽  
pp. 266-269
Author(s):  
Evgeni Semkov ◽  
Stoyanka Peneva ◽  
Sunay Ibryamov
Keyword(s):  
Light Curve ◽  
Photographic Plate ◽  
Light Curves ◽  
Curve Shape ◽  
Photometric Study ◽  
Maximum Light ◽  
Photometric Observations ◽  
Rate Of Increase ◽  
Photometric Monitoring

AbstractUsing recent data from photometric monitoring and data from the photographic plate archives we aim to study, the long-term photometric behavior of FUors. The construction of the historical light curves of FUors could be very important for determining the beginning of the outburst, the time to reach the maximum light, the rate of increase and decrease in brightness, the pre-outburst variability of the star. Our CCD photometric observations were performed with the telescopes of the Rozhen (Bulgaria) and Skinakas (Crete, Greece) observatories. Most suitable for long-term photometric study are the plate archives of the big Schmidt telescopes, as the telescopes at Kiso Observatory, Asiago Observatory, Palomar Observatory and others. In comparing our results with light curves of the well-studied FUors, we conclude that every new FUor object shows different photometric behavior. Each known FUor has a different rate of increase and decrease in brightness and a different light curve shape.

scholarly journals Secrets of the Soviet Archive: Buryat Shaman Materials in the Book of B. Rinchen

2021 ◽  
pp. 68-81
Author(s):  
Lyudmila S. Dampilova ◽  
Keyword(s):  
Comparative Analysis ◽  
Point Of View ◽  
Archival Data ◽  
Russian Academy Of Sciences ◽  
Unique Material ◽  
History Of ◽  
Tibetan Studies ◽  
Academy Of Sciences ◽  
First Time

For the first time, the author presents results of her long-term work on comparative analysis of the archive materials included in the collection of shaman texts of the Buryats of Russia “Les materiaux pour L'etude du shamanisme Mongol.” The book was published by academician B. Rinchen in Wiesbaden in 1961. As shaman texts were published without accompanying records, the scientific research cries out for comparison of texts from B. Rinchen’s anthology with archival materials of the Institute of Oriental Manuscripts of the Russian Academy of Sciences (IOS RAS) and those of the Center of Oriental Manuscripts and Xylographs of the Institute for Mongolian, Buddhist, and Tibetan Studies of the Siberian Branch of the Russian Academy of Sciences (COMX IMBTS SB RAS). Shaman materials are considered in the context of ethnocultural history of the Buryats. The author strives to reconstruct the archival data in order to identifying territorial and temporal context. The introduction of this unique material into scientific use seems significant. While working recurrently with shaman materials of the fond 62 of Ts. Zh. Zhamtsarano from the archive of the Institute of Oriental Manuscripts, a comparative analysis of archival materials and texts from the B. Rinchen’s book has been conducted. It has been identified that 19 songs from 56 texts contained in Rinchen’s book were copied from the fond 62 of Ts. Zhamtsarano. In the fond 753 of T. K. Alekseeva from the COMX IMBTS SB RAS 20 more texts have been found, that were included in the Rinchen’s book. The comparative analysis of shaman songs from the Alexeeva fond with Rinchen’s book reveals one major difference (minor variations notwithstanding): the description of rites clarify the text semantics. Repeated search and comparative analysis of materials has allowed the author to conclude that texts from the T. Alexeeva’s fond are not absent in the fond of Ts. Zhamtsarano from the archive of the IOS RAS. Thus, shaman materials published in B. Rinchen’s book can’t originate just from the C. Zhamtsarano fond, as has been formerly assumed. It is quite possible that the book mostly contains poetic songs from the fond of T. K. Alexeeva (90 of 134 pages). Thus textual comparative analysis of songs concludes that T. K. Alexeyva fond is of great scientific interest from ethnographic point of view. It is believed that future researchers may require its data for further research and publication of unique shaman materials with full supplementary records and names of collectors.

Stellar Evolution

1962 ◽  
Vol 11 (02) ◽  
pp. 137-143
Author(s):  
M. Schwarzschild
Keyword(s):  
Solar System ◽  
Stellar Evolution ◽  
Space Craft ◽  
New Techniques ◽  
Substantial Body ◽  
Individual Stars ◽  
The Past ◽  
Evolution Of Galaxies ◽  
History Of ◽  
Fast Flow

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.

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