scholarly journals ANALYSIS OF A SHORT PERIODIC PULSATOR: SX PHOENICIS STAR XX CYG

2020 ◽  
Vol 56 (2) ◽  
pp. 287-294
Author(s):  
Mohamed Abdel-Sabour ◽  
Ahmed Shokry ◽  
Ahmed Ibrahim
Keyword(s):  
Light Curve ◽  
Stellar Evolution ◽  
Light Curves ◽  
Instability Strip ◽  
Maximum Light ◽  
Photometric Observations ◽  
Ccd Observations

Photometric observations were made of the SX Phoenicis star XX Cyg between September and October 2019, using the 1.88-m Kottamia reflector telescope in Egypt. We used 340 CCD observations with blue-visible-red (BVR) filters to derive light curves. In addition, we obtained 9540 visual magnitudes for XX Cyg from the literature to prepare an observed-minus-calculated (O-C) diagram. 85 new times of maximum for XX Cyg are presented. We did not detect a bump in the descending portion of the light curve of maximum light for XX Cyg. However, we did detect a secular bump in the phased light curves, which changes with phase in some SuperWASP observations. We found the change in period of XX Cyg to be dP/dt = 15.5 × 10-5 s/yr, with its amplitude decreasing at a rate of 0.7 mmag/year. Stellar parameters of XX Cyg and its position in the instability strip of the Hertzsprung Russell stellar evolution diagram are presented.

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 Evolutionary Changes in LUMINOUS STARS

1998 ◽  
Vol 11 (1) ◽  
pp. 346-346
Author(s):  
E. Zsldos
Keyword(s):  
Light Curve ◽  
19Th Century ◽  
Stellar Evolution ◽  
Colour Change ◽  
Light Curves ◽  
Appreciable Change ◽  
Luminous Blue Variables ◽  
Secular Changes ◽  
Evolutionary Changes ◽  
The 19Th Century

The light curves of luminous stars often show spectacular secular changes which can be connected to stellar evolution. Such events are, e.g. the outbursts of P Cygni in the 17th century and 77 Carinae in the last century. Both stars belong to the Luminous Blue Variables, but these changes are not restricted to blue stars. The light curve of HR 8752 (V509 Cassiopeiae) shows a certain similarity to that of the former two stars. When it was first catalogued in the middle of the 19th century, it had been a 6m star. During 100 years the star showed a secular brightening of lm. A similar yellow hypergiant, p Cassiopeiae produced at least two outbursts this century, though both have smaller amplitudes than it is in the case of the LBVs. Moreover, these yellow variables also have an apparently secular colour change: the B − V colour of HR 8752 is decreasing while that of ρ Cassiopeiae is increasing. In both cases evolutionary changes are possible but one cannot exclude other causes. Besides these well studied stars there are several other yellow hypergiants with promising light curves. One of the most interesting cases seems to be R Puppis, which was discovered to be variable in the last century, but then did not show any appreciable change in the following 70-80 years. In the late 1970s, however, it began to vary once more.

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 The effect of stellar evolution on the light curves’ shapes of RR Lyrae stars in M3

2004 ◽  
Vol 193 ◽  
pp. 171-175
Author(s):  
Johanna Jurcsik
Keyword(s):  
Light Curve ◽  
Stellar Evolution ◽  
Light Curves ◽  
Horizontal Branch ◽  
Homogeneous Sample ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

AbstractThe light curve characteristics of a homogeneous sample of variables in M3 are studied in detail. Accurate light curves and mean magnitudes of about 100 RRab and 50 RRc stars which do not show any type of modulation are analyzed. According to their mean magnitudes and Fourier parameters the variables can be sorted into four groups, representing different stages of the horizontal branch stellar evolution.

scholarly journals TU Muscae and the Early-type Overcontact Binaries

2002 ◽  
Vol 187 ◽  
pp. 319-323
Author(s):  
Dirk Terrell
Keyword(s):  
Light Curve ◽  
Stellar Evolution ◽  
Spectroscopic Analysis ◽  
Light Curves ◽  
Early Type ◽  
Mass Ratio ◽  
Reflection Effect ◽  
Detailed Treatment

AbstractA simultaneous photometric and spectroscopic analysis of the purported early-type overcontact binary TU Muscae is presented. With a well-behaved light curve and a mass ratio far from unity, if TU Mus is indeed an overcontact system, it presents an interesting challenge for 3-D stellar evolution codes, like the Djehuty code, that will be applied to early-type overcontact binaries. The analysis shows TU Mus is slightly overcontact and that a detailed treatment of the reflection effect is important for modeling the light curves.

scholarly journals Light Curve and Orbital Period Analysis of the Eclipsing Binary AT Peg

2011 ◽  
Vol 7 (S282) ◽  
pp. 55-56
Author(s):  
Alexios Liakos ◽  
Panagiotis Niarchos ◽  
Edwin Budding
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Time Effect ◽  
Light Curves ◽  
Period Analysis ◽  
Eclipsing Binary ◽  
Secular Changes ◽  
Photometric Observations ◽  
Photometric Elements

AbstractCCD photometric observations of the Algol-type eclipsing binary AT Peg have been obtained. The light curves are analyzed with modern techniques and new geometric and photometric elements are derived. A new orbital period analysis of the system, based on the most reliable timings of minima found in the literature, is presented and apparent period modulations are discussed with respect to the Light-Time effect (LITE) and secular changes in the system. The results of these analyses are compared and interpreted in order to obtain a coherent view of the system's behaviour.

The RS CVn Type Star PZ Tel

1984 ◽  
Vol 5 (4) ◽  
pp. 540-543 ◽  
Author(s):  
J. L. Innis ◽  
D. W. Coates ◽  
K. Thompson
Keyword(s):  
Light Curve ◽  
Spectroscopic Data ◽  
Light Curves ◽  
Type Star ◽  
Maximum Light ◽  
Rapid Changes ◽  
Interesting Object ◽  
Photometric Period

AbstractWe present broadband photoelectric light curves for the RS CVn type star PZ Telescopium for 1980, 1982 and 1983. The photometric period is about 0.943 days. The V light curve shows radical changes in form and range over a few months, and may be continuously variable. B and V data were obtained in 1982 and 1983. In 1982 no (B-V) change with phase was detected. However, in the first part of the 1983 observing season, a (BV) change of around 0.02 magnitude was found. Also at this time, maximum light was some 0.05 magnitude above that measured previously. Our preliminary spectroscopic data obtained in 1983 indicate that PZ Tel is a double lined binary whose components are of approximately equal luminosities, but this is yet to be confirmed. We suggest that the photometric variations are due to the presence of large cooler starspots on the photosphere of one or both components, as seems to be the case for related systems. The rapid changes in the observed light curve imply equally rapid changes in the distribution of the starspots, and make this an interesting object for further study.

scholarly journals A search for pulsations in two Algol-type systems V1241 Tau and GQ Dra

2013 ◽  
Vol 9 (S301) ◽  
pp. 507-508 ◽  
Author(s):  
Burak Ulaş ◽  
Ceren Ulusoy ◽  
Kosmas Gazeas ◽  
Naci Erkan ◽  
Alexios Liakos
Keyword(s):  
Light Curve ◽  
Binary Systems ◽  
Type Systems ◽  
Light Variation ◽  
Light Curves ◽  
Eclipsing Binary ◽  
Photometric Observations ◽  
Fourier Techniques ◽  
Photometric Elements

AbstractWe present new photometric observations of two eclipsing binary systems, V1241 Tau and GQ Dra. We use the following methodology: initially, the Wilson-Devinney code is applied to the light curves in order to determine the photometric elements of the systems. Then, the residuals are analysed using Fourier techniques. The results are the following. One frequency can be possibly attributed to a real light variation of V1241 Tau, while there is no evidence of pulsations in the light curve of GQ Dra.

scholarly journals SN 2017gci: a nearby Type I Superluminous Supernova with a bumpy tail

2021 ◽  
Author(s):  
A Fiore ◽  
T-W Chen ◽  
A Jerkstrand ◽  
S Benetti ◽  
R Ciolfi ◽  
...  
Keyword(s):  
Initial Period ◽  
Absolute Magnitude ◽  
Emission Feature ◽  
Light Curves ◽  
Type I ◽  
Power Sources ◽  
Circumstellar Material ◽  
Maximum Light ◽  
Broad Emission ◽  
Photometric Observations

Abstract We present and discuss the optical spectro-photometric observations of the nearby (z = 0.087) Type I superluminous supernova (SLSN I) SN 2017gci, whose peak K-corrected absolute magnitude reaches Mg = −21.5 mag. Its photometric and spectroscopic evolution includes features of both slow- and of fast-evolving SLSN I, thus favoring a continuum distribution between the two SLSN-I subclasses. In particular, similarly to other SLSNe I, the multi-band light curves of SN 2017gci show two re-brightenings at about 103 and 142 days after the maximum light. Interestingly, this broadly agrees with a broad emission feature emerging around 6520 Å after ∼51 days from the maximum light, which is followed by a sharp knee in the light curve. If we interpret this feature as Hα, this could support the fact that the bumps are the signature of late interactions of the ejecta with a (hydrogen-rich) circumstellar material. Then we fitted magnetar- and CSM-interaction- powered synthetic light curves onto the bolometric one of SN 2017gci. In the magnetar case, the fit suggests a polar magnetic field Bp ≃ 6 × 1014 G, an initial period of the magnetar Pinitial ≃ 2.8 ms, an ejecta mass Mejecta ≃ 9 M⊙ and an ejecta opacity κ ≃ 0.08 cm2 g−1. A CSM-interaction scenario would imply a CSM mass ≃ 5 M⊙ and an ejecta mass ≃ 12 M⊙. Finally, the nebular spectrum of phase +187 days was modeled, deriving a mass of ∼10 M⊙ for the ejecta. Our models suggest that either a magnetar or CSM interaction might be the power sources for SN 2017gci and that its progenitor was a massive (40 M⊙) star.

scholarly journals Supernova lightCURVE POPulation Synthesis II: Validation against supernovae with an observed progenitor

2019 ◽  
Vol 36 ◽  
Author(s):  
J. J. Eldridge ◽  
N. -Y. Guo ◽  
N. Rodrigues ◽  
E. R. Stanway ◽  
L. Xiao
Keyword(s):  
Light Curve ◽  
Mass Loss ◽  
Stellar Evolution ◽  
Stellar Mass ◽  
Light Curves ◽  
Explosion Energy ◽  
Initial Mass ◽  
Multiple Models ◽  
Population Synthesis ◽  
Single Star

Abstract We use the results of a supernova light-curve population synthesis to predict the range of possible supernova light curves arising from a population of single-star progenitors that lead to type IIP supernovae. We calculate multiple models varying the initial mass, explosion energy, nickel mass and nickel mixing and then compare these to type IIP supernovae with detailed light curve data and pre-explosion imaging progenitor constraints. Where a good fit is obtained to observations, we are able to achieve initial progenitor and nickel mass estimates from the supernova lightcurve that are comparable in precision to those obtained from progenitor imaging. For 2 of the 11 IIP supernovae considered our fits are poor, indicating that more progenitor models should be included in our synthesis or that our assumptions, regarding factors such as stellar mass loss rates or the rapid final stages of stellar evolution, may need to be revisited in certain cases. Using the results of our analysis we are able to show that most of the type IIP supernovae have an explosion energy of the order of log(Eexp/ergs) = 50.52 ± 0.10 and that both the amount of nickel in the supernovae and the amount of mixing may have a dependence on initial progenitor mass.

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