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Berlin Brandenburg

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  • 1
    In: Publications of the Astronomical Society of Japan, 2011, Vol. 63(4), pp.L25-L29
    Description: We report on high-dispersion optical spectroscopic observations of the Be/X-ray binary A 0535 $+$ 262/V725 Tau during a giant outburst in 2009 November/December, and after it. The observed emission line profiles, reflecting the structure of the geometrically thin circumstellar envelope of the Be star (Be disk), show drastic variabilities, and indicate the existence of a warped component. The enhanced blue shoulder seen after periastron passage implies a gas stream from a dense part of the Be disk to the neutron star.
    Keywords: Binaries: Spectroscopic ; Stars: Emission - Line, Be ; Stars: Individual (Ariel 0535+262 = Hde 245770)
    ISSN: 0004-6264
    E-ISSN: 2053-051X
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  • 2
    Language: English
    In: Proceedings of the International Astronomical Union, 07/2010, Vol.6(S272), pp.618-619
    Description: Optical high dispersion spectroscopic observations of the Be/X-ray binary A0535+262/V725 Tau during the giant outburst will be reported. The giant outburst occurred in A0535+262 in November 2009 for the first time since 2005. We carried out the spectroscopic monitoring from November 2009. In the brightening phase of the giant outburst, the observation performed densely (almost at every night). Obtained H-alpha, H-beta and He I emission line, exhibiting dramatical profile variability during the giant outburst, has highly redshifted ( 100km/s) bright component, which had weakened before the normal outburst in March 2010. We discuss profile variability of these emission lines.
    Keywords: Astronomy & Astrophysics;
    ISBN: 9780521198400
    ISSN: 1743-9213
    E-ISSN: 1743-9221
    Source: CrossRef
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  • 3
    In: Publications of the Astronomical Society of Japan, 2012, Vol. 64(3)
    Description: The FIBRE-pac ( FMOS image-based reduction package) is an IRAF-based reduction tool for the fiber multiple-object spectrograph ( FMOS ) of the Subaru telescope. To reduce FMOS images, a number of special techniques are necessary, because each image contains about 200 separate spectra with airglow emission lines variable in spatial and time domains, and with complicated throughput patterns for airglow masks. In spite of these features, almost all of the reduction processes, except for a few steps, are carried out automatically by scripts in text format, making it easy to check the commands step by step. Wavelength- and flux-calibrated images together with their noise maps are obtained using this reduction package.
    Keywords: Instrumentation: Spectrographs ; Methods: Data Analysis
    ISSN: 0004-6264
    E-ISSN: 2053-051X
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  • 4
    In: Publications of the Astronomical Society of Japan, 2012, Vol. 64(3)
    Description: We present near-infrared spectroscopic observations of star-forming galaxies at $z$ $\sim $ 1.4 with FMOS on the Subaru Telescope. We observed $K$ -band selected galaxies in the SXDS/UDS fields with $K$ $\leq$ 23.9 mag, 1.2 $\leq$ $z_{\rm ph}$ $\leq$ 1.6, $M_{*}$ $\geq$ 10 $^{9.5}\ M_{\odot}$ , and expected F(H $\alpha $ ) $\geq$ 10 $^{-16}\ $ erg s $^{-1}\ $ cm $^{-2}$ ; 71 objects in the sample have significant detections of H $\alpha $ . For these objects, excluding possible AGNs, identified from the BPT diagram, gas-phase metallicities were obtained from the [N II ] / H $\alpha $ line ratio. The sample is split into three stellar-mass bins, and the spectra are stacked in each stellar-mass bin. The mass–metallicity relation obtained at $z$ $\sim $ 1.4 is located between those at $z$ $\sim $ 0.8 and $z$ $\sim $ 2.2. We constrain the intrinsic scatter to be $\sim $ 0.1 dex, or larger in the mass–metallicity relation at $z$ $\sim $ 1.4; the scatter may be larger at higher redshifts. We found trends that the deviation from the mass–metallicity relation depends on the SFR (Star-formation rate) and the half light radius: Galaxies with higher SFR and larger half light radii show lower metallicities at a given stellar mass. One possible scenario for the trends is the infall of pristine gas accreted from IGM, or through merger events. Our data points show larger scatter than the fundamental metallicity relation (FMR) at $z$ $\sim $ 0.1, and the average metallicities slightly deviate from the FMR. The compilation of the mass–metallicity relations at $z$ $\sim $ 3 to $z$ $\sim $ 0.1 shows that they evolve smoothly from $z$ $\sim $ 3 to $z$ $\sim $ 0 without changing the shape so much, except for the massive part at $z$ $\sim $ 0.
    Keywords: Galaxies: Abundances ; Galaxies: Evolution ; Galaxies: High - Redshift
    ISSN: 0004-6264
    E-ISSN: 2053-051X
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  • 5
    In: Publications of the Astronomical Society of Japan, 2015, Vol. 67(5)
    Description: We report on the multi-wavelength identification of the X-ray sources found in the Subaru–XMM-Newton Deep Survey (SXDS) using deep imaging data covering the wavelength range between the far-UV and mid-IR (MIR). We select a primary counterpart of each X-ray source by applying the likelihood ratio method to R -band, 3.6 μm, near-UV, and 24 μm source catalogs as well as matching catalogs of active galactic nucleus (AGN) candidates selected in 1.4 GHz radio and i  ′ -band variability surveys. Once candidates for Galactic stars, ultra-luminous X-ray sources in a nearby galaxy, and clusters of galaxies are removed there are 896 AGN candidates in the sample. We conduct spectroscopic observations of the primary counterparts with multi-object spectrographs in the optical and NIR; 65% of the X-ray AGN candidates are spectroscopically identified. For the remaining X-ray AGN candidates, we evaluate their photometric redshift with photometric data in 15 bands. Utilizing the multi-wavelength photometric data of the large sample of X-ray-selected AGNs, we evaluate the stellar masses, M * , of the host galaxies of the narrow-line AGNs. The distribution of the stellar mass is remarkably constant from z  = 0.1 to 4.0. The relation between M * and 2–10 keV luminosity can be explained with strong cosmological evolution of the relationship between the black hole mass and M * . We also evaluate the scatter of the UV–MIR spectral energy distribution (SED) of the X-ray AGNs as a function of X-ray luminosity and absorption by the nucleus. The scatter is compared with galaxies which have redshift and stellar mass distribution matched with the X-ray AGN. The UV–NIR (near-IR) SEDs of obscured X-ray AGNs are similar to those of the galaxies in the matched sample. In the NIR–MIR range, the median SEDs of X-ray AGNs are redder, but the scatter of the SEDs of the X-ray AGN broadly overlaps that of the galaxies in the matched sample.
    Keywords: Catalogs ; Galaxies: Active ; Quasars: General ; Surveys ; X - Rays: Galaxies
    E-ISSN: 0004-6264
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  • 6
    In: Publications of the Astronomical Society of Japan, 2010, Vol. 62(1), pp.187-199
    Description: We report on the observation of a new dwarf nova (DN), OT J055717 $+$ 683226 (OT: optical transient), during the period of its first-recorded superoutburst in 2006 December. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67 $\pm$ 0.03 min (0.05324 $\pm$ 0.00002 d). The next superoutburst was observed in 2008 March. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be $\sim$ 480 d. The supercycle ( $\sim$ 480 d) is much shorter than those ( $〉rsim$ 10 yr) of WZ Sge-type dwarf novae which are in the major of dwarf novae in the shortest orbital period regime ( $\lesssim$ 85 min). Using a hierarchical cluster analysis, we divided the dwarf nova in the shortest orbital period regime in seven groups. We found that objects, which have short supercycles, small outburst amplitudes, and large superhump period excesses compared with those of WZ Sge stars, form a small group. OT J055717 $+$ 683226 probably belongs to this group.
    Keywords: Accretion, Accretion Disks ; Stars: Individual (Ot J055717+683226) ; Novae, Cataclysmic Variables
    ISSN: 0004-6264
    E-ISSN: 2053-051X
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  • 7
    In: Publications of the Astronomical Society of Japan, 2010, Vol. 62(5), pp.1135-1147
    Description: Fibre Multi-Object Spectrograph (FMOS) is the first near-infrared instrument with a wide field of view capable of acquiring spectra simultaneously from up to 400 objects. It has been developed as a common-use instrument for the F $/$ 2 prime-focus of the Subaru Telescope. The field coverage of 30 $^\prime$ diameter is achieved using a new 3-element corrector optimized in the near-infrared (0.9–1.8 $\ \mu$ m) wavelength range. Due to limited space at the prime-focus, we have had to develop a novel fibre positioner, called “Echidna”, together with two OH-airglow suppressed spectrographs. FMOS consists of three subsystems: the prime focus unit for IR, the fibre positioning system/connector units, and the two spectrographs. After full systems integration, FMOS was installed on the telescope in late 2007. Many aspects of the performance were checked through various test and engineering observations. In this paper, we present the optical and mechanical components of FMOS, and show the results of our on-sky engineering observations to date.
    Keywords: Cosmology: Observations ; Instrumentation: Spectrographs ; Surveys ; Telescopes: Subaru
    ISSN: 0004-6264
    E-ISSN: 2053-051X
    Source: Oxford University Press
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  • 8
    In: Publications of the Astronomical Society of Japan, 2009, Vol. 61(4), pp.L17-L21
    Description: We report on time-resolved CCD photometry of the 2005 March/April superoutburst of a recently confirmed SU UMa-type dwarf nova, 1RXS J053234+624755. The superoutburst was accompanied by a precursor in which conspicuous superhumps were visible from the second night of the precursor. This is a rare example where superhumps were observed during a precursor. Concerning an estimated mass ratio of 0.07 for the system, the present observations contrast with the well-known Lubow relation. We also found that the superhump period increased as the superoutburst proceeded, despite the fact that the superoutburst showed a precursor. If the superhump-period change is closely related to the disk radius of the superoutburst, systems having a small mass ratio could display an increasing superhump period, even if the superoutburst contains a precursor.
    Keywords: Accretion, Accretion Disks ; Stars: Dwarf Novae ; Stars: Individual (1rxs J053234+624755) ; Stars: Novae, Cataclysmic Variables ; Stars: Oscillations
    ISSN: 0004-6264
    E-ISSN: 2053-051X
    Source: Oxford University Press
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  • 9
    Description: Fibre Multi-Object Spectrograph (FMOS) is the first near-infrared instrument with a wide field of view capable of acquiring spectra simultaneously from up to 400 objects. It has been developed as a common-use instrument for the F/2 prime-focus of the Subaru Telescope. The field coverage of 30' diameter is achieved using a new 3-element corrector optimized in the near-infrared (0.9-1.8um) wavelength range. Due to limited space at the prime-focus, we have had to develop a novel fibre positioner called "Echidna" together with two OH-airglow suppressed spectrographs. FMOS consists of three subsystems: the prime focus unit for IR, the fibre positioning system/connector units, and the two spectrographs. After full systems integration, FMOS was installed on the telescope in late 2007. Many aspects of performance were checked through various test and engineering observations. In this paper, we present the optical and mechanical components of FMOS and show the results of our on-sky engineering observations to date. Comment: Accepted for publication in PASJ, 12 pages, 23 figures
    Keywords: Astrophysics - Instrumentation And Methods For Astrophysics
    Source: Cornell University
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  • 10
    In: Publications of the Astronomical Society of Japan, 2009, Vol. 61(4), pp.697-705
    Description: We carried out an international spectroscopic observation campaign of the dwarf nova GW Librae (GW Lib) during its 2007 superoutburst. Our observation period covered the rising phase of the superoutburst, maximum, slowly decaying phase (plateau), and long fading tail phase after the rapid decline from the plateau. The spectral features dramatically changed during the observations. In the rising phase, only absorption lines of H $\alpha$ , H $\beta$ , and H $\gamma$ were present. Around the maximum, the spectrum showed singly peaked emission lines of H $\alpha$ , He i 5876, He i 6678, He ii 4686, and C iii /N iii as well as absorption lines of the Balmer components and HeI. These emission lines significantly weakened during the latter part of the plateau phase. In the fading tail phase, all of the Balmer lines and He i 6678 were in emission, as observed in quiescence. We find that the center of the H $\alpha$ emission component was mostly stable over the whole orbital phase, being consistent with the low inclination of the system. Compared with the observational results of WZ Sagittae during its 2001 superoutburst, the same type of stars as GW Lib seen with a high inclination angle, we interpret that the change of the H $\alpha$ profile before the fading tail phase can be attributed to a photoionized region formed at the outer edge of the accretion disk, irradiated from the white dwarf and inner disk.
    Keywords: Accretion, Accretion Disks ; Stars: Dwarf Novae ; Stars: Individual (Gw Librae) ; Stars: Novae, Cataclysmic Variables
    ISSN: 0004-6264
    E-ISSN: 2053-051X
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