SN1993J: CHALLENGING NEW INSIGHTS FOR STELLAR STRUCTURE AND SUPERNOVA THEORIES

The appearance of supernova SN1993J in our nearby galaxy M81 is an important event in the modern study of supernovae. From the very beginning it created puzzles regarding its supernova type; then in its evolution further puzzles particularly in its spectra, light curve, nature of progenitor, X-ray and γ-ray emission, polarization, etc. Various puzzles have been solved with the help of both theoretical and observational investigations. Still many problems remain. In this present review we examine the gradual development of the various puzzles along with the evolution of SN1993J. We have also presented the unsolved problems as well as the important aspects which are to be measured. We particularly emphasize on the measurements of the shell structure of a radio supernova and of the asymmetry of the scattering envelope as a test to verify the prediction of shell structure in supernova theory i.e. supernova SN1993J will give us an opportunity to verify various aspects of supernova theory.

Download Full-text

Optical, X-ray, and γ-ray observations of the candidate transitional millisecond pulsar 4FGL J0427.8-6704

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa912 ◽

2020 ◽

Vol 494 (3) ◽

pp. 3912-3926

Author(s):

M R Kennedy ◽

R P Breton ◽

C J Clark ◽

V S Dhillon ◽

M Kerr ◽

...

Keyword(s):

Light Curve ◽

Time Scales ◽

Periodic Oscillation ◽

Optical Data ◽

Data Sets ◽

Millisecond Pulsar ◽

X Ray ◽

State Classification ◽

Optical Light Curve ◽

Γ Ray

ABSTRACT We present an optical, X-ray, and γ-ray study of 1SXPS J042749.2-670434, an eclipsing X-ray binary that has an associated γ-ray counterpart, 4FGL J0427.8-6704. This association has led to the source being classified as a transitional millisecond pulsar (tMSP) in an accreting state. We analyse 10.5 yr of Fermi LAT data and detect a γ-ray eclipse at the same phase as optical and X-ray eclipses at the >5 σ level, a significant improvement on the 2.8 σ level of the previous detection. The confirmation of this eclipse solidifies the association between the X-ray source and the γ-ray source, strengthening the tMSP classification. However, analysis of several optical data sets and an X-ray observation do not reveal a change in the source’s median brightness over long time-scales or a bi-modality on short time-scales. Instead, the light curve is dominated by flickering, which has a correlation time of 2.6 min alongside a potential quasi-periodic oscillation at ∼21 min. The mass of the primary and secondary stars is constrained to be $M_1=1.43^{+0.33}_{-0.19}$ M⊙ and $M_2=0.3^{+0.17}_{-0.12}$ M⊙ through modelling of the optical light curve. While this is still consistent with a white dwarf primary, we favour the tMSP in a low accretion state classification due to the significance of the γ-ray eclipse detection.

Download Full-text

Optical/UV afterglows: Swift UVOT overview

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2006.1982 ◽

2007 ◽

Vol 365 (1854) ◽

pp. 1227-1234 ◽

Cited By ~ 1

Author(s):

Keith O Mason ◽

Patricia Boyd ◽

Mathew Page ◽

Shashi Pandey ◽

Pete Roming ◽

...

Keyword(s):

Light Curve ◽

Spectral Data ◽

Gamma Ray ◽

Gamma Ray Bursts ◽

Nearby Galaxy ◽

Host Galaxies ◽

Optical Telescope ◽

X Ray ◽

Diagnostic Power ◽

Peculiar Case

The ultraviolet and optical telescope (UVOT) on Swift provides coverage of gamma-ray bursts and their afterglows in the 170–650 nm band, yielding multiwavelength data of considerable diagnostic power in conjunction with the Swift X-ray Telescope. The results from the first eighteen months of operation show a broad range of afterglow behaviour, with considerably more complexity in many bursts than would be expected from the simple fireball model for the explosion. We briefly illustrate the capabilities of UVOT for measuring the evolution of nearby supernovae by reference to the observations of GRB 060218, and discuss the peculiar case of GRB 060614, which apparently resides in a nearby galaxy but which did not show the expected supernova feature in its light curve due to radioactive nickel decay. We discuss how the combination of X-ray and UV/optical spectral data can be used to investigate the environment of GRB host galaxies.

Download Full-text

GRB 070311: A COMMON ORIGIN FOR THE PROMPT AND AFTERGLOW EMISSION

International Journal of Modern Physics D ◽

10.1142/s0218271808012917 ◽

2008 ◽

Vol 17 (09) ◽

pp. 1359-1362 ◽

Cited By ~ 1

Author(s):

◽

S. D. VERGANI ◽

C. GUIDORZI

Keyword(s):

Light Curve ◽

Power Law ◽

Time Profile ◽

Common Origin ◽

Light Curves ◽

X Ray ◽

Γ Ray ◽

Prompt Emission

GRB 070311 was a long burst that triggered INTEGRAL. We present prompt γ-ray, early NIR/optical, late optical and X-ray data on this burst and its afterglow. Interestingly, the H-band light curve acquired with REM exhibits two pulses at 80 and 140 s after the peak of the γ-ray burst, with possible evidence for a contemporaneous faint γ-ray tail. The late optical and X-ray afterglow underwent a rebrightening between 3 × 104 and 2 × 105 s after the burst with energy comparable with that of the prompt emission extrapolated in the X-ray band. After fitting the early γ-ray and optical light curves, we modelled the time profile of the late rebrightening as the time-rescaled version of the prompt γ-ray pulse over an underlying power law. This result supports a common origin for both prompt and late X-ray/optical afterglow rebrightening of GRB 070311 within the external shock scenario.

Download Full-text

Visual Light from the Eclipsing Supersoft X-Ray Source Cal 87

International Astronomical Union Colloquium ◽

10.1017/s0252921100039312 ◽

1996 ◽

Vol 158 ◽

pp. 425-426 ◽

Cited By ~ 1

Author(s):

S. Schandl ◽

E. Meyer-Hofmeister ◽

F. Meyer

Keyword(s):

Light Curve ◽

Accretion Disk ◽

White Dwarf ◽

Hot Spot ◽

Roche Lobe ◽

X Ray ◽

Secondary Star ◽

The Asymmetry ◽

The Absolute ◽

Visual Light

We calculate the visual light curve of CAL 87 based on the assumption that an accreting, steadily burning white dwarf irradiates the accretion disk and the secondary star, as suggested by van den Heuvel et al. (1992). The shape of the eclipse light curve and the absolute luminosities put strong constraints on the contributions of the various elements in the system. We find a reasonable fit is obtained with the following sources of visual light: a Roche lobe filling secondary star where the energy from irradiation is spread out over the surface, and an accretion disk with an optically thick, cold, clumpy spray which is caused by the massive accretion stream impinging on the disk (hot spot). This spray moving around the disk and illuminated by the white dwarf is found to be the brightest source of visual light in the binary and can account for the asymmetry in the light curve.

Download Full-text

An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2012.20772.x ◽

2012 ◽

Vol 423 (2) ◽

pp. 993-1005 ◽

Cited By ~ 11

Author(s):

J. Jurcsik ◽

Á. Sódor ◽

G. Hajdu ◽

B. Szeidl ◽

Á. Dózsa ◽

...

Keyword(s):

Light Curve ◽

Light Curves ◽

Stellar Structure ◽

Time Base ◽

Photometric Method ◽

Physical Parameters ◽

Component Solution ◽

Rr Lyrae ◽

Curve Variation ◽

Type Variable

Abstract The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time base of ∼110 yr, a strict anticorrelation between the pulsation- and modulation-period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121-d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-averaged values of the physical parameters in different phases of both modulation components are determined.

Download Full-text

X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834116 ◽

2018 ◽

Vol 619 ◽

pp. A138

Author(s):

V. Perdelwitz ◽

S. Czesla ◽

J. Robrade ◽

T. Pribulla ◽

J. H. M. M. Schmitt

Keyword(s):

Binary System ◽

Light Curve ◽

Binary Systems ◽

Uv Light ◽

Close Binary ◽

Eclipsing Binary ◽

X Ray ◽

Uv Emission ◽

Low Mass ◽

Orbital Modulation

Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We extend the sample of low-mass binary systems with well-known X-ray properties. Methods.We analyze data from a singular XMM-Newton pointing of the close, low-mass eclipsing binary system BX Tri. The UV light curve was modeled with the eclipsing binary modeling tool PHOEBE and data acquired with the EPIC cameras was analyzed to search for hints of orbital modulation. Results.We find clear evidence of orbital modulation in the UV light curve and show that PHOEBE is fully capable of modeling data within this wavelength range. Comparison to a theoretical flux prediction based on PHOENIX models shows that the majority of UV emission is of photospheric origin. While the X-ray light curve does exhibit strong variations, the signal-to-noise ratio of the observation is insufficient for a clear detection of signs of orbital modulation. There is evidence of a Neupert-like correlation between UV and X-ray data.

Download Full-text

Application of Energy Dispersive X-ray Fluorescence, γ-ray Spectrometry and Multivariate Statistical Approach for the Soil Classification of Samples from Douala – Cameroon

Radiation Physics and Chemistry ◽

10.1016/j.radphyschem.2021.109589 ◽

2021 ◽

pp. 109589

Author(s):

Joel Cebastien SHOUOP GUEMBOU ◽

Maurice MOYO. NDONTCHUENG ◽

Jilbert Eric MEKONGTSO NGUELEM ◽

Ousmanou MOTAPON ◽

David STRIVAY

Keyword(s):

Statistical Approach ◽

Soil Classification ◽

Energy Dispersive ◽

Multivariate Statistical ◽

X Ray ◽

Multivariate Statistical Approach ◽

Γ Ray

Download Full-text

Urca nuclide production in Type-I X-ray bursts and implications for nuclear physics studies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3414 ◽

2020 ◽

Vol 500 (3) ◽

pp. 2958-2968

Author(s):

Grant Merz ◽

Zach Meisel

Keyword(s):

Light Curve ◽

Nuclear Reaction ◽

Nuclear Physics ◽

Thermal Structure ◽

Reaction Rates ◽

High Mass ◽

Type I ◽

Model Calculations ◽

X Ray ◽

Lower Temperature

ABSTRACT The thermal structure of accreting neutron stars is affected by the presence of urca nuclei in the neutron star crust. Nuclear isobars harbouring urca nuclides can be produced in the ashes of Type I X-ray bursts, but the details of their production have not yet been explored. Using the code MESA, we investigate urca nuclide production in a one-dimensional model of Type I X-ray bursts using astrophysical conditions thought to resemble the source GS 1826-24. We find that high-mass (A ≥ 55) urca nuclei are primarily produced late in the X-ray burst, during hydrogen-burning freeze-out that corresponds to the tail of the burst light curve. The ∼0.4–0.6 GK temperature relevant for the nucleosynthesis of these urca nuclides is much lower than the ∼1 GK temperature most relevant for X-ray burst light curve impacts by nuclear reaction rates involving high-mass nuclides. The latter temperature is often assumed for nuclear physics studies. Therefore, our findings alter the excitation energy range of interest in compound nuclei for nuclear physics studies of urca nuclide production. We demonstrate that for some cases this will need to be considered in planning for nuclear physics experiments. Additionally, we show that the lower temperature range for urca nuclide production explains why variations of some nuclear reaction rates in model calculations impacts the burst light curve but not local features of the burst ashes.

Download Full-text