High-State/Low-State Behavior in the Long-Term Light Curve of V Sagittae

1997 ◽  
Vol 113 ◽  
pp. 787 ◽  
Author(s):  
Jeff W. Robertson ◽  
R. Kent Honeycutt ◽  
Jeffrey R. Pier
Keyword(s):  
Light Curve ◽  
High State ◽  
State Behavior

scholarly journals Light curve analysis of the late type binary V523 Cassiopeiae

2009 ◽  
pp. 45-48 ◽  
Author(s):  
O. Latkovic ◽  
M. Zboril ◽  
G. Djurasevic
Keyword(s):  
Light Curve ◽  
Monitoring Program ◽  
Neck Region ◽  
Bright Spot ◽  
Late Type ◽  
Light Curve Analysis ◽  
Type Contact ◽  
Contact Binary ◽  
Previous Solution

We present the analysis of V and R light curves of the late type contact binary V523 Cas for the season of 2006. These observations make part of the monitoring program aimed at studying the long-term light curve variability in this system. Our results confirm that the system is in an over contact configuration, and include a bright spot in the neck region of the cooler and larger primary. We compare these results with the previous solution, obtained for the season 2005 dataset and discuss the differences.

scholarly journals A REMARKABLE LONG-TERM LIGHT CURVE AND DEEP, LOW-STATE SPECTROSCOPY: SWIFT AND XMM-NEWTON MONITORING OF THE NLS1 GALAXY Mkn 335

2012 ◽  
Vol 199 (2) ◽  
pp. 28 ◽  
Author(s):  
Dirk Grupe ◽  
S. Komossa ◽  
Luigi C. Gallo ◽  
Anna Lia Longinotti ◽  
Andrew C. Fabian ◽  
...  
Keyword(s):  
Light Curve

scholarly journals A pre-outburst signal in the long-term optical light curve of the recurrent nova RS Ophiuchi

2011 ◽  
Vol 414 (3) ◽  
pp. 2195-2203 ◽  
Author(s):  
S. Adamakis ◽  
S. P. S. Eyres ◽  
A. Sarkar ◽  
R. W. Walsh
Keyword(s):  
Light Curve ◽  
Optical Light Curve ◽  
Recurrent Nova

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 Long-term Study of the Light Curve of PKS 1510-089 in GeV Energies

2017 ◽  
Vol 844 (1) ◽  
pp. 62 ◽  
Author(s):  
Raj Prince ◽  
Pratik Majumdar ◽  
Nayantara Gupta
Keyword(s):  
Light Curve ◽  
Term Study ◽  
Long Term Study

scholarly journals The Long-Term Variability of Luminous Blue Variables

1999 ◽  
Vol 169 ◽  
pp. 243-248
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Light Curve ◽  
Luminous Blue Variables ◽  
Second Peak ◽  
Hr Diagram

AbstractThe stars known as Luminous Blue Variables include two very distinctive subgroups - the S Dor-type variables which basically define what we call an LBV and the much rarer ‘giant eruption’ LBV’s which include famous stars like η Car and P Cyg. The distinctive characteristics and long term variability of these two groups is reviewed. The lesser 1890 eruption of η Car is shown to have been much more significant than previously believed and resembles the second peak seen in the historic light curve of P Cyg. Because so many, if not all, stars in certain parts of the HR diagram appear to be luminous, blue, and variable, I suggest returning to our previous designation - S Dor variables and η Car variables for these two important groups of stars.

scholarly journals X-ray spectra and light curves of cooling novae and a nova like

2020 ◽  
Vol 499 (2) ◽  
pp. 3006-3018
Author(s):  
Bangzheng Sun ◽  
Marina Orio ◽  
Andrej Dobrotka ◽  
Gerardo Juan Manuel Luna ◽  
Sergey Shugarov ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Rate ◽  
High Energy ◽  
Gravitational Energy ◽  
Light Curves ◽  
Clear Correlation ◽  
X Rays ◽  
High State ◽  
X Ray ◽  
Low X

ABSTRACT We present X-ray observations of novae V2491 Cyg and KT Eri about 9 yr post-outburst of the dwarf nova and post-nova candidate EY Cyg, and of a VY Scl variable. The first three objects were observed with XMM–Newton, KT Eri also with the Chandra ACIS-S camera, V794 Aql with the Chandra ACIS-S camera and High Energy Transmission Gratings. The two recent novae, similar in outburst amplitude and light curve, appear very different at quiescence. Assuming half of the gravitational energy is irradiated in X-rays, V2491 Cyg is accreting at $\dot{m}=1.4\times 10^{-9}{\!-\!}10^{-8}\,{\rm M}_\odot \,{\rm yr}^{-1}$, while for KT Eri, $\dot{m}\lt 2\times 10^{-10}{\rm M}_\odot \,{\rm yr}$. V2491 Cyg shows signatures of a magnetized WD, specifically of an intermediate polar. A periodicity of  39 min, detected in outburst, was still measured and is likely due to WD rotation. EY Cyg is accreting at $\dot{m}\sim 1.8\times 10^{-11}{\rm M}_\odot \,{\rm yr}^{-1}$, one magnitude lower than KT Eri, consistently with its U Gem outburst behaviour and its quiescent UV flux. The X-rays are modulated with the orbital period, despite the system’s low inclination, probably due to the X-ray flux of the secondary. A period of  81 min is also detected, suggesting that it may also be an intermediate polar. V794 Aql had low X-ray luminosity during an optically high state, about the same level as in a recent optically low state. Thus, we find no clear correlation between optical and X-ray luminosity: the accretion rate seems unstable and variable. The very hard X-ray spectrum indicates a massive WD.

scholarly journals The Long-term Variation in the RV Tauri Star U Mon

1995 ◽  
Vol 155 ◽  
pp. 409-410 ◽  
Author(s):  
Karen R. Pollard ◽  
P. L. Cottrell
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Radial Velocity ◽  
Tauri Star ◽  
Short Term ◽  
Instability Strip ◽  
Term Variation ◽  
Velocity Variations

The RV Tauri stars are semiregular pulsating variables located in the brightest part of the Cepheid II instability strip. They have a characteristic light curve of alternating deep and shallow minima. A subset of the RV Tauri stars (the RVb subclass) exhibit long-term (500 to 2600 day) light and radial velocity variations. Although it is well established that the short-term variations are due to pulsations, the long-term behaviour is not well understood.BVRI photometry and high-resolution spectra of U Mon (the brightest member of the RVb subclass) were obtained at the Mt John University Observatory (MJUO) between 1990 Aug and 1994 May. The light and colour curves obtained clearly show the long-term variation in U Mon (Fig. 1(a) and (b)). The reddest colours occur slightly later than the long-term minimum in the light curve. The short-term light and colour variations are ‘damped’ at the long-term minimum.

Superhump period of SDSS J214354.59+124457.8: First Z Cam star with superhumps in the standstill

2019 ◽  
Vol 489 (1) ◽  
pp. 1451-1462
Author(s):  
Metin Altan ◽  
Taichi Kato ◽  
Ryoko Ishioka ◽  
Linda Schmidtobreick ◽  
Tolga Güver ◽  
...  
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Timing Analysis ◽  
Periodic Signal ◽  
Mass Ratio ◽  
Short Intervals ◽  
Upper Limit ◽  
Term Variation ◽  
Two Phases

Abstract The cataclysmic variable SDSS J214354.59+124457.8 (hereafter SDSS J214354) was observed photometrically on sixty one nights between 2012 July 28 and 2019 May 26. The long term variation of this object shows changes between two phases; a dwarf nova type and a novalike. This implies that the object belongs to the group of Z Cam type stars. The timing analysis of the light curve reveals a periodic signal at 0.13902(5) d, which we identify as the superhump period. However, the fractional superhump excess of 10 per cent longer than the orbital period is exceptionally large. We obtained a mass ratio of ∼0.4, which is above the accepted upper limit of q = 0.33 for the formation of superhumps. We suggest that the object contains a secondary with an evolved core. With an orbital period of 0.126 d, SDSS J214354 is situated at the upper border of the period gap. The long term light curve of SDSS J214354 is similar to those of Z Cam type stars which are characterized by recurring standstills, followed by short intervals with DN type outbursts. Therefore, we conclude that SDSS J214354 is a new member of the Z Cam type stars.

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