A5101467964- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Astro and Planetary Science
- Laser-Plasma Interactions and Diagnostics
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- High-pressure geophysics and materials
- Geophysics and Gravity Measurements
- Advanced X-ray Imaging Techniques
- Solar and Space Plasma Dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Superconducting Materials and Applications
- Diamond and Carbon-based Materials Research
- Mechanics and Biomechanics Studies
- Historical Astronomy and Related Studies
- Ionosphere and magnetosphere dynamics
- Spacecraft and Cryogenic Technologies
- History and Developments in Astronomy
- Tropical and Extratropical Cyclones Research
Liverpool John Moores University
2013-2023
Botswana International University of Science and Technology
2018-2023
Consejo Superior de Investigaciones Científicas
2016
Technical University of Denmark
2016
University of Münster
1997
Keele University
1982-1984
Los Alamos National Laboratory
1982
Swift X-ray observations of the ∼60 day supersoft phase recurrent nova RS Ophiuchi (RS Oph) 2006 show progress nuclear burning on white dwarf (WD) in exquisite detail. First seen 26 days after optical outburst, this started with extreme variability likely due to variable absorption, although intrinsic WD variations are not excluded. About 32 later, a steady decline count rate set in. NLTE model atmosphere spectral fits during that effective temperature increases from ∼65 eV ∼90 phase,...
ABSTRACT The Andromeda Galaxy recurrent nova M31N 2008-12a had been observed in eruption 10 times, including yearly eruptions from 2008 to 2014. With a measured recurrence period of <?CDATA ${P}_{\mathrm{rec}}=351\pm 13$?> days (we believe the true value be half this) and white dwarf very close Chandrasekhar limit, has become leading pre-explosion supernova type Ia progenitor candidate. Following multi-wavelength follow-up observations 2013 2014 eruptions, we initiated campaign ensure early...
We report the results of our statistical study POINT-AGAPE CNe catalogue. The first Sloan $r'$ and $i'$ analysis MMRD relationship in M31 is performed using resulting CN Good fits are produced to two filters. However, we unable verify $t_{15}$ for either filter. subsequent automated detection pipeline has provided us with most thorough knowledge completeness a survey to-date. In addition, large field view permitted probe outburst rate well into galactic disk, unlike previous CCD imaging...
view Abstract Citations (72) References (75) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Detailed Study of the Remnant Nova GK Persei and Its Environs Seaquist, E. R. ; Bode, M. F. Frail, D. A. Roberts, J. Evans, Albinson, S. Observational data on nova remnant its environs at a variety wavelengths are presented discussed. The suggest that exploded into circumstellar cloud whose mass is estimated to be several solar masses mean diameter pc. Radio images...
The phase of Super-Soft-Source (SSS) emission the sixth recorded outburst recurrent nova RS Oph was observed twice with Chandra and once XMM-Newton. observations were taken on days 39.7, 54.0, 66.9 after outburst. We confirm a 35-sec period day 54.0 found that it originates from SSS not shock. discus bound-free absorption by neutral elements in line sight, resonance lines plus self-absorbed components, collisionally excited shock, He-like intersystem lines, spectral changes during an episode...
We present a multiwavelength analysis of 63 Gamma-Ray Bursts observed with the world's three largest robotic optical telescopes, Liverpool and Faulkes Telescopes (North South). Optical emission was detected for 24 GRBs brightnesses ranging from R = 10 to 22 mag in first minutes after burst. By comparing X-ray light curves t 100 about 10^6 seconds, we introduce four main classes, defined by presence or absence temporal breaks at and/or wavelengths. While 15/24 can be modelled forward-shock...
We report Hubble Space Telescope imaging, obtained 155 and 449 days after the 2006 outburst of recurrent nova RS Ophiuchi, together with ground-based spectroscopic observations, from Observatorio Astron\'omico Nacional en San Pedro M\'artir, Baja California, M\'exico at Astrof\'isico Guillermo Haro, Cananea, Sonora, M\'exico. The observations first epoch were used as inputs to model geometry kinematic structure evolving Oph nebular remnant. find that modeled remnant comprises two distinct...
We report the results of a multi-year spectroscopic and photometric survey novae in M31 that resulted total 53 spectra 48 individual nova candidates. Two these, M31N 1995-11e 2007-11g, were revealed to be long-period Mira variables, not novae. These data double number extant for through end 2009 bring 91 with known classifications. find 75 (82%) are confirmed or likely members Fe II class, remaining 16 (18%) belonging He/N (and related) classes. numbers consistent those found Galactic no...
V745 Sco is a recurrent nova, with the most recent eruption occurring in February 2014. was first observed by Swift mere 3.7 h after announcement of optical discovery, super-soft X-ray emission being detected around 4 d later and lasting for only ∼2 d, making it both fastest follow-up nova earliest switch-on yet detected. Such an early time suggests combination very high velocity outflow low ejected mass and, together effective temperature reached emission, white dwarf (>1.3 M⊙). The...
We present extensive, high-density Swift observations of V2491 Cyg (Nova 2008 No. 2). Observing the X-ray emission from only one day after nova discovery, source is followed through initial brightening, Super-Soft Source phase and back to pre-outburst flux level. The evolution spectrum throughout outburst demonstrated. UV light-curves follow very different paths, although changes occur in them around same times, indicating a link between bands. Flickering late-time data indicates resumption...
We present new X-ray observations of V838 Her (Nova 1991), made using the Position Sensitive Proportional Counter and Telescope aboard ROSAT. The data, taken a year after outburst, show that flux from decreased dramatically its value 5 d outburst. interpret data in terms shocked-gas model, argue shock-heating must take place as result interaction different components within ejecta. A hydrodynamic calculation demonstrates that, with reasonable values for mass-loss rate ejection speed, model...
The 2-m Liverpool Telescope (LT), owned by John Moores University, is located in La Palma (Canary Islands) and operates fully robotic mode. In 2005, the LT began conducting an automatic GRB follow-up program. On receiving alert from a Gamma-Ray Observatory (Swift, INTEGRAL, HETE-II, IPN) initiates special override mode that conducts observations within 2-3 min of onset. This procedure begins with initial sequence short (10-s) exposures acquired through r' band filter. These images are...
The POINT–AGAPE (Pixel-lensing Observations with the Isaac Newton Telescope–Andromeda Galaxy Amplified Pixels Experiment) survey is an optical search for gravitational microlensing events towards Andromeda galaxy (M31). As well as microlensing, sensitive to many different classes of variable stars and transients. Here we describe automated detection selection pipeline used identify M31 classical novae (CNe) present resulting catalogue 20 CN candidates observed over three seasons. CNe are...
Nova Oph 2009 (V2672 Oph) reached maximum brightness V= 11.35 on August 16.5. With observed t2(V) = 2.3 and t3(V) 4.2 d decline times, it is one of the fastest known novae, being rivalled only by V1500 Cyg (1975) V838 Her (1991) among classical U Sco recurrent ones. The line sight to nova passes within a few degrees Galactic Centre. reddening V2672 E(B−V) 1.6 ± 0.1, its distance d∼ 19 kpc places other side Centre at galactocentric larger than solar one. lack an infrared counterpart for...
We present multi-frequency radio observations of the 2010 nova event in symbiotic binary V407 Cygni, obtained with Karl G. Jansky Very Large Array (VLA) and spanning 1–45 GHz 17–770 days following discovery. This nova—the first ever detected gamma rays—shows a light curve dominated by wind Mira giant companion, rather than ejecta themselves. The luminosity grew as became increasingly ionized outburst, faded was violently heated from within shock. study marks time that this physical mechanism...
Determining the evolution of ejecta morphology novae provides valuable information on shaping mechanisms in operation at early stages nova outburst. Understanding such has implications for studies example proto-Planetary Nebulae. Here we perform morpho-kinematical V2491 Cyg using spectral data to determine likely structure and its relationship central system mechanisms. We use shape model different morphologies retrieve their spectra. These synthetic spectra are compared with observed most...
Context. Super-soft-source (SSS) X-ray spectra are blackbody-like with effective temperatures ~3−7 × 105 K and luminosities of 1035−38 erg s-1. Grating SSS novae in outburst that show type display atmospheric absorption lines. Radiation transport atmosphere models can be used to derive physical parameters. Blue-shifted lines suggest hydrostatic equilibrium is an insufficient assumption, more sophisticated required.
The reported positions of 964 suspected nova eruptions in M31 recorded through the end calendar year 2013 have been compared order to identify recurrent candidates. To pass initial screen and qualify as a candidate two or more were required be coincident within 0.1', although this criterion was relaxed 0.15' for novae discovered on early photographic patrols. A total 118 from 51 potential systems satisfied screening criterion. determine what fraction these are indeed original plates...
Abstract Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and high accretion rate, which is most promising candidate for single-degenerate progenitor of Type Ia supernova known to date. The previous three eruptions have displayed remarkably homogeneous multiwavelength properties: (i) from faint peak, optical light curve declined rapidly by two...
The recurrent nova M31N 2008-12a experiences annual eruptions, contains a near-Chandrasekhar mass white dwarf, and has the largest accretion rate in any system. In this paper, we present Hubble Space Telescope (HST) WFC3/UVIS photometry of late decline 2015 eruption. We couple these new data with archival HST observations quiescent system Keck spectroscopy 2014 late-time reveals rapid to minimum luminosity state, before possible recovery / re-brightening run-up next Comparison disk models...