Gamma-ray bursts and supernovae

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• YUKI KANEKO

We present a systematic spectral analysis of 350 bright GRBs observed with BATSE, with high spectral and temporal resolution. Our sample was selected from the complete set of 2704 BATSE GRBs, and included 17 short GRBs. To obtain well-constrained spectral parameters, four different photon models were fitted and the sp…

• YUKI KANEKO

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• YUKI KANEKO

Soft gamma repeaters (SGRs) and anomalous x-ray pulsars form a rapidly increasing group of x-ray sources exhibiting sporadic emission of short bursts. They are believed to be magnetars, that is, neutron stars powered by extreme magnetic fields, B ~ 10(14) to 10(15) gauss. We report on a soft gamma repeater with low ma…

• ERSİN GÖĞÜŞ

We present a homogeneous set of stellar atmospheric parameters (T-eff, log g, [Fe/H]) for MILES, a new spectral stellar library covering the range lambda lambda 3525-7500 angstrom at 2.3 angstrom (FWHM) spectral resolution. The library consists of 985 stars spanning a large range in atmospheric parameters, from super-…

• SELİM OSMAN SELAM

We present a new study of the collisional runaway scenario to form an intermediate-mass black hole (IMBH, MBH≳ 100 M⊙) at the centre of a young, compact stellar cluster. The first phase is the formation of a very dense central core of massive stars (M*≃ 30–120 M⊙) through mass segregation and gravothermal collapse. Pr…

• MEHMET ATAKAN GÜRKAN

We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst (GRB) of the past 29 yr. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z = 0.340, indicating that its unprecedented brightness is primarily the result of its relative…

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• YUKI KANEKO

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• YUKI KANEKO

The evolved solar-type stars 16 Cyg A and B have long been studied as solar analogs, yielding a glimpse into the future of our own Sun. The orbital period of the binary system is too long to provide meaningful dynamical constraints on the stellar properties, but asteroseismology can help because the stars are among th…

• ZEYNEP ÇELİK ORHAN

The evolved solar-type stars 16 Cyg A and B have long been studied as solar analogs, yielding a glimpse into the future of our own Sun. The orbital period of the binary system is too long to provide meaningful dynamical constraints on the stellar properties, but asteroseismology can help because the stars are among th…

• MUTLU YILDIZ

We report on the long-term X-ray monitoring with Swift , RXTE , Suzaku , Chandra , and XMM-Newton of the outburst of the newly discovered magnetar Swift J1822.3−1606 (SGR 1822−1606), from the first observations soon after the detection of the short X-ray bursts which led to its discovery, through the first stages of i…

• ERSİN GÖĞÜŞ