Showing papers by "H. Bruntt published in 2004"
TL;DR: The X-Ray Flash (XRF) is the closest γ-Ray Burst (GRB) or XRF known to date as mentioned in this paper, with a host galaxy at z = 0.1055, and a significant increase and subsequent decrease in the apparent brightness of the host, peaking between 10 and 33 days after the GRB.
Abstract: The X-Ray Flash (XRF), 031203 with a host galaxy at z = 0.1055, is, apart from GRB 980425, the closest γ-Ray Burst (GRB) or XRF known to date. We have monitored its host galaxy from 1-100 days after the burst. In spite of the high extinction to the source and the bright host, a significant increase and subsequent decrease has been detected in the apparent brightness of the host, peaking between 10 and 33 days after the GRB. The only convincing explanation is a supernova (SN) associated with the XRF, SN2003lw. This is the earliest time at which a SN signal is clearly discernible in a GRB/XRF (apart from SN1998bw). SN2003lw is extremely luminous with a broad peak and can be approximately represented by the lightcurve of SN1998bw brightened by ∼0.55 mag, implying a hypernova, as observed in most GRB-SNe. The XRF-SN association firmly links XRFs with the deaths of massive stars and further strengthens their connection with GRBs. The fact that SNe are also associated with XRFs implies that Swift may detect a significant population of intermediate redshift SNe very soon after the SN explosions, a sample ideally suited for detailed studies of early SN physics.
91 citations
TL;DR: In this paper, the authors present a detailed abundance analysis of nine of the potential main targets using the semi-automatic software , and find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors.
Abstract: One of the goals of the ground-based support program for the and / satellite missions is to charac- terize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential main targets using the semi-automatic software . For two additional targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff ,l ogg ,a nd (Fe/H) to within 70−100 K, 0.1−0.2 dex, and 0.1 dex for five stars which are slow rotators (v sini 60 km s −1 ) it is not possible to constrain the atmospheric parameters.
79 citations
TL;DR: In this article, the authors present the detailed abundance analysis of nine of the potential COROT main targets using the semi-automatic software VWA, and find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors.
Abstract: One of the goals of the ground-based support program for the COROT and Roemer satellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential COROT main targets using the semi-automatic software VWA. For two additional COROT targets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the VWA software. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff, log g, and [Fe/H] to within 70-100 K, 0.1-0.2 dex, and 0.1 dex for five stars which are slow rotators (v sin i 60 km/s it is not possible to constrain the atmospheric parameters.
72 citations
TL;DR: In this paper, an analysis of observations of the bright star Altair (alpha Aql) obtained using the star camera on the Wide-Field Infrared Explorer (WIRE) satellite is presented.
Abstract: We present an analysis of observations of the bright star Altair (alpha Aql) obtained using the star camera on the Wide-Field Infrared Explorer (WIRE) satellite. Although Altair lies within the delta Scuti instability strip, previous observations have not revealed the presence of oscillations. However, the WIRE observations show Altair to be a low-amplitude (Delta m < 1 ppt) delta Scuti star with at least 7 modes present.
52 citations