A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interfe... more A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground-and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams.
Received date................; accepted date............... Abstract. The orbit and physical para... more Received date................; accepted date............... Abstract. The orbit and physical parameters of the previously unsolved double-lined eclipsing binary V570 Per, discovered by the Hipparcos satellite, are derived using high resolution Echelle spectroscopy and B, V photoelectric photometry. The metallicity from χ 2 analysis of the spectra is [M/H]=+0.02±0.03, and reddening from interstellar NaI and KI absorption lines is EB−V =0.023±0.007. V570 Per is a well detached system, with shallow eclipses due to low orbital inclination and no sign of chromospheric activity. The two components have masses of 1.449±0.006 and 1.350±0.006 M ⊙ and spectral types F3 and F5, respectively. They are both still within the Main Sequence band (T1=6842±25 K, T2=6562±25 K from χ 2 analysis, R1=1.523±0.030, R2=1.388±0.019 R⊙ derived forcing the orbital solution to conform to the spectroscopic light ratio) and are dynamically relaxed to co-rotation with the orbital motion (Vrot sin i1,2=40 and 36 (±...
Abstract. The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and r... more Abstract. The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and recurrent nova U Sco is presented. The photometric evolution closely matches that of the previous events. The FWZI=10,000 km sec −1 for emission lines at maximum has decreased to 4000 km sec −1 by day +23, with continuous and dramatic changes in the line profiles. No nebular line has become visible and the ionization degree has increased during the brightness decline. A not previously reported and quite puzzling splitting of the emission lines into three components after the first two weeks is outstanding in our spectra. The radiated luminosity is found to be a tiny fraction of that of classical novae for any reasonable distance to U Sco.
Low resolution B&C+CCD (range 3600 ˚ A - 1.0 m) and high resolution Echelle+CCD (range 5800-8100 ... more Low resolution B&C+CCD (range 3600 ˚ A - 1.0 m) and high resolution Echelle+CCD (range 5800-8100 ˚ A) spec- trophotometry of type Ib/c SN 1997X near maximum light is presented and discussed. The supernova is notheworthy in hav- ing presented absorption lines of He I at early phases (at an expansion velocity of 11000 km sec 1 ). From the interstellar NaI D lines a reddening of EB V =0.180.02 mag has been de- rived, which arises in the host galaxy. From the emission lines of the underlying H II region, a density of Ne 100 and a velocity of RV=1098 3k m sec 1 are obtained.
SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric... more SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric phase observational coverage. Here, we present Very Large Telescope and Public ESO Spectroscopic Survey of Transient Objects observations of this SN in the nebular phase. We model the nebular [O I] λλ6300, 6364 lines and find their strength to suggest a progenitor main-sequence mass of 13–15 M . SN 2012ec is unique among hydrogen-rich SNe in showing a distinct line of stable nickel [Ni II] λ7378. This line is produced by 58Ni, a nuclear burning ash whose abundance is a sensitive tracer of explosive burning conditions. Using spectral synthesis modelling, we use the relative strengths of [Ni II] λ7378 and [Fe II] λ7155 (the progenitor of which is 56Ni) to derive a Ni/Fe production ratio of 0.20 ± 0.07 (by mass), which is a factor 3.4 ± 1.2 times the solar value. High production of stable nickel is confirmed by a strong [Ni II] 1.939 μm line. This is the third reported case of a core-colla...
We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in ... more We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in galaxy M74, from 1 to 450 d after the explosion. SN 2013ej is a hydrogen-rich supernova, classified as a Type IIL due to its relatively fast decline following the initial peak. It has a relatively high peak luminosity (absolute magnitude MV = −17.6) but a small 56Ni production of ∼0.023 M . Its photospheric evolution is similar to other Type II SNe, with shallow absorption in the Hα profile typical for a Type IIL. During transition to the radioactive decay tail at ∼100 d, we find the SN to grow bluer in B − V colour, in contrast to some other Type II supernovae. At late times, the bolometric light curve declined faster than expected from 56Co decay and we observed unusually broad and asymmetric nebular emission lines. Based on comparison of nebular emission lines most sensitive to the progenitor core mass, we find our observations are best matched to synthesized spectral models with a MZ...
Monthly Notices of the Royal Astronomical Society, 2021
We present the photometric and spectroscopic analysis of three Type II supernovae (SNe): 2014cx, ... more We present the photometric and spectroscopic analysis of three Type II supernovae (SNe): 2014cx, 2014cy, and 2015cz. SN 2014cx is a conventional Type IIP with shallow slope (0.2 mag/50 d) and an atypical short plateau (∼86 d). SNe 2014cy and 2015cz show relatively large decline rates (0.88 and 1.64 mag/50 d, respectively) at early times before settling to the plateau phase, unlike the canonical Type IIP/L SN light curves. All of them are normal luminosity SN II with an absolute magnitude at mid-plateau of M$_{V,14\mathrm{ cx}}^{50}$=$-16.6\, \pm \, 0.4\, \rm {mag}$, M$_{V,14\mathrm{ cy}}^{50}$=$-16.5\, \pm \, 0.2\, \rm {mag}$, and M$_{V,15\mathrm{ cz}}^{50}$=$-17.4\, \pm \, 0.3\, \rm {mag}$. A relatively broad range of 56Ni masses is ejected in these explosions (0.027–0.070 M⊙). The spectra shows the classical evolution of SNe II, dominated by a blue continuum with broad H lines at early phases and narrower metal lines with P Cygni profiles during the plateau. High-velocity H i f...
A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interfe... more A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground-and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams.
Received date................; accepted date............... Abstract. The orbit and physical para... more Received date................; accepted date............... Abstract. The orbit and physical parameters of the previously unsolved double-lined eclipsing binary V570 Per, discovered by the Hipparcos satellite, are derived using high resolution Echelle spectroscopy and B, V photoelectric photometry. The metallicity from χ 2 analysis of the spectra is [M/H]=+0.02±0.03, and reddening from interstellar NaI and KI absorption lines is EB−V =0.023±0.007. V570 Per is a well detached system, with shallow eclipses due to low orbital inclination and no sign of chromospheric activity. The two components have masses of 1.449±0.006 and 1.350±0.006 M ⊙ and spectral types F3 and F5, respectively. They are both still within the Main Sequence band (T1=6842±25 K, T2=6562±25 K from χ 2 analysis, R1=1.523±0.030, R2=1.388±0.019 R⊙ derived forcing the orbital solution to conform to the spectroscopic light ratio) and are dynamically relaxed to co-rotation with the orbital motion (Vrot sin i1,2=40 and 36 (±...
Abstract. The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and r... more Abstract. The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and recurrent nova U Sco is presented. The photometric evolution closely matches that of the previous events. The FWZI=10,000 km sec −1 for emission lines at maximum has decreased to 4000 km sec −1 by day +23, with continuous and dramatic changes in the line profiles. No nebular line has become visible and the ionization degree has increased during the brightness decline. A not previously reported and quite puzzling splitting of the emission lines into three components after the first two weeks is outstanding in our spectra. The radiated luminosity is found to be a tiny fraction of that of classical novae for any reasonable distance to U Sco.
Low resolution B&C+CCD (range 3600 ˚ A - 1.0 m) and high resolution Echelle+CCD (range 5800-8100 ... more Low resolution B&C+CCD (range 3600 ˚ A - 1.0 m) and high resolution Echelle+CCD (range 5800-8100 ˚ A) spec- trophotometry of type Ib/c SN 1997X near maximum light is presented and discussed. The supernova is notheworthy in hav- ing presented absorption lines of He I at early phases (at an expansion velocity of 11000 km sec 1 ). From the interstellar NaI D lines a reddening of EB V =0.180.02 mag has been de- rived, which arises in the host galaxy. From the emission lines of the underlying H II region, a density of Ne 100 and a velocity of RV=1098 3k m sec 1 are obtained.
SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric... more SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric phase observational coverage. Here, we present Very Large Telescope and Public ESO Spectroscopic Survey of Transient Objects observations of this SN in the nebular phase. We model the nebular [O I] λλ6300, 6364 lines and find their strength to suggest a progenitor main-sequence mass of 13–15 M . SN 2012ec is unique among hydrogen-rich SNe in showing a distinct line of stable nickel [Ni II] λ7378. This line is produced by 58Ni, a nuclear burning ash whose abundance is a sensitive tracer of explosive burning conditions. Using spectral synthesis modelling, we use the relative strengths of [Ni II] λ7378 and [Fe II] λ7155 (the progenitor of which is 56Ni) to derive a Ni/Fe production ratio of 0.20 ± 0.07 (by mass), which is a factor 3.4 ± 1.2 times the solar value. High production of stable nickel is confirmed by a strong [Ni II] 1.939 μm line. This is the third reported case of a core-colla...
We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in ... more We present optical and near-infrared photometric and spectroscopic observations of SN 2013ej, in galaxy M74, from 1 to 450 d after the explosion. SN 2013ej is a hydrogen-rich supernova, classified as a Type IIL due to its relatively fast decline following the initial peak. It has a relatively high peak luminosity (absolute magnitude MV = −17.6) but a small 56Ni production of ∼0.023 M . Its photospheric evolution is similar to other Type II SNe, with shallow absorption in the Hα profile typical for a Type IIL. During transition to the radioactive decay tail at ∼100 d, we find the SN to grow bluer in B − V colour, in contrast to some other Type II supernovae. At late times, the bolometric light curve declined faster than expected from 56Co decay and we observed unusually broad and asymmetric nebular emission lines. Based on comparison of nebular emission lines most sensitive to the progenitor core mass, we find our observations are best matched to synthesized spectral models with a MZ...
Monthly Notices of the Royal Astronomical Society, 2021
We present the photometric and spectroscopic analysis of three Type II supernovae (SNe): 2014cx, ... more We present the photometric and spectroscopic analysis of three Type II supernovae (SNe): 2014cx, 2014cy, and 2015cz. SN 2014cx is a conventional Type IIP with shallow slope (0.2 mag/50 d) and an atypical short plateau (∼86 d). SNe 2014cy and 2015cz show relatively large decline rates (0.88 and 1.64 mag/50 d, respectively) at early times before settling to the plateau phase, unlike the canonical Type IIP/L SN light curves. All of them are normal luminosity SN II with an absolute magnitude at mid-plateau of M$_{V,14\mathrm{ cx}}^{50}$=$-16.6\, \pm \, 0.4\, \rm {mag}$, M$_{V,14\mathrm{ cy}}^{50}$=$-16.5\, \pm \, 0.2\, \rm {mag}$, and M$_{V,15\mathrm{ cz}}^{50}$=$-17.4\, \pm \, 0.3\, \rm {mag}$. A relatively broad range of 56Ni masses is ejected in these explosions (0.027–0.070 M⊙). The spectra shows the classical evolution of SNe II, dominated by a blue continuum with broad H lines at early phases and narrower metal lines with P Cygni profiles during the plateau. High-velocity H i f...
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