scholarly journals Discovery of a new WZ Sagittae-type cataclysmic variable in the Kepler/K2 data

2019 ◽  
Vol 490 (4) ◽  
pp. 5551-5559 ◽  
Author(s):  
R Ridden-Harper ◽  
B E Tucker ◽  
P Garnavich ◽  
A Rest ◽  
S Margheim ◽  
...  
Keyword(s):  
Light Curve ◽  
Power Law ◽  
Orbital Period ◽  
Type System ◽  
Cataclysmic Variable ◽  
Linear Rise ◽  
Early Rise ◽  
Power Law Index ◽  
Nova Outburst ◽  
Unusual Type

ABSTRACT We identify a new, bright transient in the K2/Kepler Campaign 11 field. Its light curve rises over 7 mag in a day and then declines 3 mag over a month before quickly fading another 2 mag. The transient was still detectable at the end of the campaign. The light curve is consistent with a WZ Sge-type dwarf nova outburst. Early superhumps with a period of 82 min are seen in the first 10 days and suggest that this is the orbital period of the binary, which is typical for the WZ Sge class. Strong superhump oscillations develop 10 days after peak brightness with periods ranging between 83 and 84 min. At 25 days after the peak brightness a bump in the light curve appears to signal a subtle rebrightening phase implying that this was an unusual type-A outburst. This is the only WZ Sge-type system observed by K2/Kepler during an outburst. The early rise of this outburst is well fitted with a broken power law. In first 10 h, the system brightened linearly and then transitioned to a steep rise with a power-law index of 4.8. Looking at archival K2/Kepler data and new TESS observations, a linear rise in the first several hours at the initiation of a superoutburst appears to be common in SU Ursa Majoris stars.

scholarly journals ASASSN-18tb: a most unusual Type Ia supernova observed by TESS and SALT

2019 ◽  
Vol 487 (2) ◽  
pp. 2372-2384 ◽  
Author(s):  
P J Vallely ◽  
M Fausnaugh ◽  
S W Jha ◽  
M A Tucker ◽  
Y Eweis ◽  
...  
Keyword(s):  
Light Curve ◽  
Power Law ◽  
Type Ia Supernovae ◽  
Normal Type ◽  
Type Ia Supernova ◽  
Type Ia ◽  
Early Rise ◽  
Ia Supernovae ◽  
Best Fit ◽  
Unusual Type

ABSTRACT We present photometric and spectroscopic observations of the unusual Type Ia supernova ASASSN-18tb, including a series of Southern African Large Telescope spectra obtained over the course of nearly six months and the first observations of a supernova by the Transiting Exoplanet Survey Satellite. We confirm a previous observation by Kollmeier et al. showing that ASASSN-18tb is the first relatively normal Type Ia supernova to exhibit clear broad (∼1000 km s−1) H α emission in its nebular-phase spectra. We find that this event is best explained as a sub-Chandrasekhar mass explosion producing $M_{\mathrm{ Ni}} \approx 0.3\,\, \rm {M}_\odot$. Despite the strong H α signature at late times, we find that the early rise of the supernova shows no evidence for deviations from a single-component power-law and is best fit with a moderately shallow power law of index 1.69 ± 0.04. We find that the H α luminosity remains approximately constant after its initial detection at phase +37 d, and that the H α velocity evolution does not trace that of the Fe iii λ4660 emission. These suggest that the H α emission arises from a circumstellar medium (CSM) rather than swept-up material from a non-degenerate companion. However, ASASSN-18tb is strikingly different from other known CSM-interacting Type Ia supernovae in a number of significant ways. Those objects typically show an H α luminosity two orders of magnitude higher than what is seen in ASASSN-18tb, pushing them away from the empirical light-curve relations that define ‘normal’ Type Ia supernovae. Conversely, ASASSN-18tb exhibits a fairly typical light curve and luminosity for an underluminous or transitional SN Ia, with MR ≈ −18.1 mag. Moreover, ASASSN-18tb is the only SN Ia showing H α from CSM interaction to be discovered in an early-type galaxy.

scholarly journals New Exosat Observations of TV Columbae: Preliminary Results

1987 ◽  
Vol 93 ◽  
pp. 261-267
Author(s):  
J. Schrijver ◽  
A.C. Brinkman ◽  
H. Van Der Woerd
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
White Dwarf ◽  
Lower Energy ◽  
Cataclysmic Variable ◽  
X Ray ◽  
Preliminary Results ◽  
First Results ◽  
Absorption Features ◽  
Energy Channels

AbstractThe first results of the analysis of new EXOSAT observations of the DQ Her type cataclysmic variable TV Col are presented. The period of the 1–10 kev X-ray pulsation associated with the white-dwarf rotation is now established as 1911 s. The pulsations are most pronounced in the lower energy channels (1–3.5 keV). The X-ray light curve shows absorption features associated with the orbital period of the system.

scholarly journals Photometric Evidence for the Presence of An Accretion Disk and for a Superhump - Like Phenomenon in the Classical Nova V1974 Cygni 1992

1997 ◽  
Vol 163 ◽  
pp. 788-789
Author(s):  
A. Retter ◽  
E.M. Leibowitz ◽  
E.O. Ofek
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Disk Model ◽  
Classical Nova ◽  
Nova Outburst

AbstractThe light curve of V1974 Cyg shows two distinct periodicities. The shorter periodicity is clearly the orbital period of the binary system. We show that the longer variation has similar features to permanent superhumps. This result indicates the existence of an accretion disk in the system no later than 30 months after the nova outburst. We used the precessing disk model of the superhump phenomenon and previous results in order to estimate that the white dwarf mass is at the range 0.75 – 1.07 M⊙.

scholarly journals A Photometric Study of the Newly Discovered Eclipsing Cataclysmic Variable SDSS J040714.78–064425.1

2005 ◽  
Vol 22 (2) ◽  
pp. 105-110 ◽  
Author(s):  
T. Ak ◽  
A. Retter ◽  
A. Liu ◽  
H. H. Esenoğlu
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
Cataclysmic Variable ◽  
Photometric Study ◽  
Dwarf Nova ◽  
Ccd Observations ◽  
Optical Light Curve ◽  
Orbital Periods

AbstractWe present the results obtained from unfiltered photometric CCD observations of the newly discovered cataclysmic variable SDSS J040714.78–064425.1 made during seven nights in 2003 November. We establish the dwarf nova nature of the object as it was in outburst during our observations. We also confirm the presence of deep eclipses with a period of 0.17017 ± 0.00003 d in the optical light curve of the star. In addition, we found periods of 0.166 ± 0.001 d and possibly also 5.3 ± 0.7 d in the data. The 0.17017 d periodicity is consistent within the errors with the proposed orbital period of 0.165 and 0.1700 d. Using the known relation between the orbital and superhump periods, we interpret the 0.166 and 5.3 d periods as the negative superhump and the nodal precession period respectively. SDSS J040714.78–064425.1 is then classified as a negative superhump system with one of the largest orbital periods.

scholarly journals Results of 5-year photometric monitoring of the intermediate polar V2306 Cygni: correction of the orbital period and evidence of 2-day periodicity

2015 ◽  
Vol 5 (1) ◽  
pp. 17-20
Author(s):  
V. Breus ◽  
K. Petrík ◽  
S. Zoła ◽  
A. Baransky ◽  
T. Hegedus
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Cataclysmic Variable ◽  
Firm Conclusion ◽  
Spin Period ◽  
Photometric Monitoring

We present the results of 6 years of photometric monitoring of the magnetic cataclysmic variable V2306 Cygni (formerly known as 1WGAJ1958.2+3232) obtained at collaborating observatories. Using (O-C) analysis we tried to study variability of the spin period of the white dwarf, however we cannot make a firm conclusion based on the scatter. Simultaneously, using (O-C) diagram of orbital minima, we found that the value of 0.181545(3) days better corresponds with the light curve, than do previously published orbital period values. We also found that the variability has a 2.01 day period; this variability may be interpreted as possible precession of the accretion disk in this system.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

RSCVn Stars in the Southern Hemisphere

1979 ◽  
Vol 46 ◽  
pp. 371-384 ◽  
Author(s):  
J.B. Hearnshaw
Keyword(s):  
Light Curve ◽  
Southern Hemisphere ◽  
Orbital Period ◽  
Binary Stars ◽  
Small Amplitude ◽  
Light Variation ◽  
Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

Elastic Foundation Analysis of Uniformly Loaded Functionally Graded Viscoelastic Sandwich Plates

2012 ◽  
Vol 28 (3) ◽  
pp. 439-452 ◽  
Author(s):  
A. M. Zenkour ◽  
M. Sobhy
Keyword(s):  
Power Law ◽  
Sandwich Plate ◽  
Plate Theory ◽  
Functionally Graded ◽  
Sandwich Plates ◽  
Equilibrium Equations ◽  
Graded Material ◽  
Plate Aspect Ratio ◽  
Type V ◽  
Power Law Index

AbstractThis paper deals with the static response of simply supported functionally graded material (FGM) viscoelastic sandwich plates subjected to transverse uniform loads. The FG sandwich plates are considered to be resting on Pasternak's elastic foundations. The sandwich plate is assumed to consist of a fully elastic core sandwiched by elastic-viscoelastic FGM layers. Material properties are graded according to a power-law variation from the interfaces to the faces of the plate. The equilibrium equations of the FG sandwich plate are given based on a trigonometric shear deformation plate theory. Using Illyushin's method, the governing equations of the viscoelastic sandwich plate can be solved. Parametric study on the bending analysis of FG sandwich plates is being investigated. These parameters include (i) power-law index, (ii) plate aspect ratio, (iii) side-to-thickness ratio, (iv) loading type, (v) foundation stiffnesses, and (vi) time parameter.

scholarly journals Jet Impingement Heat Transfer of Confined Single and Double Jets with Non-Newtonian Power Law Nanofluid under the Inclined Magnetic Field Effects for a Partly Curved Heated Wall

2021 ◽  
Vol 13 (9) ◽  
pp. 5086
Author(s):  
Fatih Selimefendigil ◽  
Hakan F. Oztop ◽  
Ali J. Chamkha
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Particle Size ◽  
Aspect Ratio ◽  
Power Law ◽  
Volume Fraction ◽  
Inclined Magnetic Field ◽  
Magnetic Field Effects ◽  
Power Law Nanofluid ◽  
Power Law Index

Single and double impinging jets heat transfer of non-Newtonian power law nanofluid on a partly curved surface under the inclined magnetic field effects is analyzed with finite element method. The numerical work is performed for various values of Reynolds number (Re, between 100 and 300), Hartmann number (Ha, between 0 and 10), magnetic field inclination (γ, between 0 and 90), curved wall aspect ratio (AR, between 01. and 1.2), power law index (n, between 0.8 and 1.2), nanoparticle volume fraction (ϕ, between 0 and 0.04) and particle size in nm (dp, between 20 and 80). The amount of rise in average Nusselt (Nu) number with Re number depends upon the power law index while the discrepancy between the Newtonian fluid case becomes higher with higher values of power law indices. As compared to case with n = 1, discrepancy in the average Nu number are obtained as −38% and 71.5% for cases with n = 0.8 and n = 1.2. The magnetic field strength and inclination can be used to control the size and number or vortices. As magnetic field is imposed at the higher strength, the average Nu reduces by about 26.6% and 7.5% for single and double jets with n greater than 1 while it increases by about 4.78% and 12.58% with n less than 1. The inclination of magnetic field also plays an important role on the amount of enhancement in the average Nu number for different n values. The aspect ratio of the curved wall affects the flow field slightly while the average Nu variation becomes 5%. Average Nu number increases with higher solid particle volume fraction and with smaller particle size. At the highest particle size, it is increased by about 14%. There is 7% variation in the average Nu number when cases with lowest and highest particle size are compared. Finally, convective heat transfer performance modeling with four inputs and one output is successfully obtained by using Adaptive Neuro-Fuzzy Interface System (ANFIS) which provides fast and accurate prediction results.

scholarly journals Blocks Size Frequency Distribution in the Enceladus Tiger Stripes Area: Implications on Their Formative Processes

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 82
Author(s):  
Maurizio Pajola ◽  
Alice Lucchetti ◽  
Lara Senter ◽  
Gabriele Cremonese
Keyword(s):  
Frequency Distribution ◽  
Power Law ◽  
Size Frequency Distribution ◽  
Surface Stresses ◽  
Size Frequency ◽  
The One ◽  
Power Law Index ◽  
Comet 67P ◽  
South Polar ◽  
Degree Of Fragmentation

We study the size frequency distribution of the blocks located in the deeply fractured, geologically active Enceladus South Polar Terrain with the aim to suggest their formative mechanisms. Through the Cassini ISS images, we identify ~17,000 blocks with sizes ranging from ~25 m to 366 m, and located at different distances from the Damascus, Baghdad and Cairo Sulci. On all counts and for both Damascus and Baghdad cases, the power-law fitting curve has an index that is similar to the one obtained on the deeply fractured, actively sublimating Hathor cliff on comet 67P/Churyumov-Gerasimenko, where several non-dislodged blocks are observed. This suggests that as for 67P, sublimation and surface stresses favor similar fractures development in the Enceladus icy matrix, hence resulting in comparable block disaggregation. A steeper power-law index for Cairo counts may suggest a higher degree of fragmentation, which could be the result of localized, stronger tectonic disruption of lithospheric ice. Eventually, we show that the smallest blocks identified are located from tens of m to 20–25 km from the Sulci fissures, while the largest blocks are found closer to the tiger stripes. This result supports the ejection hypothesis mechanism as the possible source of blocks.

Sign in / Sign up

Export Citation Format

Share Document