133 research outputs found
Detection of the irradiated donor in the LMXBs 4U 1636-536 (=V801 Ara) and 4U 1735-444 (=V926 Sco)
No full textPhase-resolved VLT spectroscopy of the bursting low-mass X-ray binaries 4U 1636-536/V801 Ara and 4U 1735-444/V926 Sco is presented. Doppler images of the N iiiλ4640 Bowen transition reveal compact spots which we attribute to fluorescent emission from the donor star and enable us to define a new set of spectroscopic ephemerides. We measure Kem= 277 ± 22 and 226 ± 22 km s−1 from the N iii spots in V801 Ara and V926 Sco, respectively, which represent strict lower limits to the radial velocity semi-amplitude of the donor stars. Our new ephemerides provide confirmation that light-curve maxima in V801 Ara and likely V926 Sco occur at superior conjunction of the donor star and hence photometric modulation is caused by the visibility of the X-ray heated donor. The velocities of He iiλ4686 and the broad Bowen blend are strongly modulated with the orbital period, with phasing supporting emission dominated by the disc bulge. In addition, a reanalysis of burst oscillations in V801 Ara, using our spectroscopic T0, leads to K1= 90–113 km s−1. We also estimate the K-corrections for all possible disc flaring angles and present the first dynamical constraints on the masses of these X-ray bursters. These are K2= 360 ± 74 km s−1, f(M) = 0.76 ± 0.47 M⊙ and q= 0.21–0.34 for V801 Ara and K2= 298 ± 83 km s−1, f(M) = 0.53 ± 0.44 M⊙ and q= 0.05–0.41 for V926 Sco. Disc flaring angles α≥ 12° and q≃ 0.26–0.34 are favoured for V801 Ara whereas the lack of K1 constraint for V926 Sco prevents tight constraints on this system. Although both binaries seem to have intermediate inclinations, the larger equivalent width of the narrow N iii line in V801 Ara at phase 0.5 relative to phase 0 suggests that it has the higher inclination of the two
The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. I. The optically thick phase and the origin of moving lines in novae
No full textAims: We aim to derive the physical properties of the recurrent nova T Pyx and the structure of the ejecta during the early stages of expansion of the 2011 outburst.
Methods: The nova was observed with high resolution spectroscopy (R ≈ 65 000), from one day after discovery of the outburst and until the last visibility of the star at the end of May 2011. The interstellar absorption lines of Na I, Ca II, CH, CH+, and archival H I 21 cm emission line observations were used to determine a kinematical distance. Interstellar diffuse absorption features have been used to determine the extinction independent of previous assumptions. Sample Fe-peak line profiles show the optical depth and radial velocity evolution of the discrete components.
Results: We propose a distance to T Pyx ≥ 4.5 kpc, with a strict lower limit of 3.5 kpc (the previously accepted distance). We derive an extinction, E(B - V) ≈ 0.5 ± 0.1, that is higher than previous estimates. The first observation, Apr. 15, displayed He I, He II, C III, and N III emission lines and a maximum velocity derived from the P Cyg profiles of the Balmer and He I lines of ≈2500 km s-1 that is characteristic of the fireball stage. These ions were undetectable in the second spectrum, Apr. 23, and we use the recombination time to estimate the mass of the ejecta, 10-5f Msun for a filling factor f. Numerous absorption-line systems were detected in the Balmer, Fe-peak, Ca II, and Na I lines, mirrored in broader emission-line components, that showed an "accelerated" displacement in velocity. We also show that the time sequence of these absorptions, which are common to all lines and arise only in the ejecta, can be described by a recombination front moving outward in the expanding gas without either a stellar wind or circumstellar collisions. By the end of May, the ejecta were showing signs of turning optically thin in the ultraviolet
Phase-resolved spectroscopy of the low-mass X-ray binaries 1636-536/V801 Arae and 1735-444/V926 Scorpii
No full textPhase-resolved spectroscopy of the low-mass X-ray binaries 1636-536/V801 Arae and 1735-444/V926 Scorpii Augusteijn, T.; van der Hooft, F.; de Jong, J.A.; van Kerkwijk, M.H.; van Paradijs, J.A. Published in: Astronomy & Astrophysics Link to publication Citation for published version (APA): Augusteijn, T., van der Hooft, F., de Jong, J. A., van Kerkwijk, M. H., & van Paradijs, J. A. (1998). Phaseresolved spectroscopy of the low-mass X-ray binaries 1636-536/V801 Arae and 1735-444/V926 Scorpii. Astronomy & Astrophysics, 332, 561-568. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract. We present phase-resolved spectroscopy of the optical counterparts V 801 Ara and V 926 Sco of the low-mass X-ray binaries 1636-536 and 1735-444. To assist in the interpretation of the spectroscopic observations we derive new ephemerides for the photometric variations of both sources. Superior conjunction of the line emission region occurs at photometric phase ∼0.7 in both sources, which indicates that these variations are dominated by a component originating from the point where the mass stream from the donor star intersects the outer disk. We find that the properties of 1636-536/V 801 Ara and 1735-444/V 926 Sco are very similar
Perigrinatie ofte veertichiarige reyse der kinderen Israels uyt Egipten, door de Roodezee : mitsgaders de woestyne tot in 't beloofde landt Canaan : met groote vlijt uyt verscheyden auctoren by een gestelt, uyt de H.Schrift gecorigeert, ende in 't licht g
No full textGenummerd rechtsonder: 3 | Beschreven in: Poortman en Augusteijn, Kaarten in bijbels p. 247 |
The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II. The optically thin phase and the structure of the ejecta in recurrent novae
No full textAims. We continue our study of the physical properties of the recurrent nova T Pyx, focussing on the structure of the ejecta in the nebular stage of expansion during the 2011 outburst.
Methods. The nova was observed contemporaneously with the Nordic Optical Telescope (NOT), at high resolution spectroscopic resolution (R ≈ 65 000) on 2011 Oct. 11 and 2012 Apr. 8 (without absolute flux calibration), and with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST), at high resolution (R ≈ 30 000) on 2011 Oct. 10 and 2012 Mar. 28 (absolute fluxes). The NOT spectra cover 3800–7300 Å, the HST spectra from 2011 Oct. cover 1150–5700 Å while the 2012 Mar. spectrum covers 1150–1700 Å. We use standard plasma diagnostics (e.g. [O III] and [N II] line ratios and the Hβ line fluxes) to constrain electron densities and temperatures. Using Monte Carlo modeling of the ejecta, we derive the structure and filling factor from comparisons to the optical and ultraviolet line profiles.
Results. The ejecta can be modeled using an axisymmetric conical – bipolar – geometry with a low inclination of the axis to the line of sight, i = 15 ± 5 degrees, compatible with published results from high angular resolution optical spectro-interferometry. The structure is similar to that observed in the other short orbital period recurrent novae (e.g. CI Aql, U Sco) and RNe candidate KT Eri during their nebular stages. We show that the electron density scales as t-3 as expected from a ballistically ejected constant mass shell; there is no need to invoke a continuing mass outflow following the eruption. The derived mass for the ejecta with filling factor f ≈ 3%, Mej ≈ 2 × 10-6 M⊙ is similar to that obtained for other recurrent nova ejecta but inconsistent with the previously reported extended optically thick epoch of the explosion. We suggest that the system underwent a common envelope phase following the explosion that produced the recombination event. Implications for the dynamics of the recurrent novae are discussed.
Conclusions. The compact recurrent novae can be understood within a single phenomenological model with bipolar, although not jet-like, low mass ejecta
De gelegentheyt van 't Paradys ende 't landt Canaan : mitsgaders d' eerst bewoonde landen der patriarchen
No full textGenummerd rechtsonder : 5 | Beschreven in: Poortman en Augusteijn, Kaarten in bijbels p. 206 |
De gelegentheyt van 't Paradys ende 't landt Canaan : mitsgaders de eerst bewoonde landen der patriarchen
No full textGenummerd rechtsonder : 2 | Beschreven in: Poortman en Augusteijn, Kaarten in bijbels p. 246 |
The spectroscopic evolution of the symbiotic-like recurrent nova V407 Cygni during its 2010 outburst. I. The shock and its evolution
No full textContext. V407 Cyg was, before 2010 Mar., known only as a D-type symbiotic binary system in which the Mira variable has a pulsation period of approximately 750 days, one of the longest known. On 2010 Mar. 10, it was discovered in outburst, eventually reaching V < 8. This is the first recorded nova event for this system, but it closely resembles the spectroscopic development of RS Oph, the prototypical symbiotic-like recurrent nova. It was also detected by Fermi above 100 MeV and displayed strong, likely nonthermal centimeter wavelength radio emission.
Aims: Unlike classical novae occurring in compact cataclysmic binary systems, for which the ejecta undergo free ballistic expansion, this explosion occurred within the dense, complex wind of a Mira variable companion. This paper concentrates on the development of the shock and its passage through the Mira wind. We also present some constraints on the binary system properties.
Methods: Using medium and high resolution ground-based optical spectra, visual and Swift UV photometry, and Swift X-ray spectrophotometry, we describe the behavior of the high-velocity profile evolution for this nova during its first three months.
Results: Using the diffuse interstellar bands visible in the high-resolution optical spectra, we obtain an extinction E(B - V) ≈ 0.45 ± 0.05. The spectral type of the red giant during this period, when the star was at R minimum, was no earlier than M7 III. The peak of the X-ray emission occurred at about day 40 with a broad maximum and decline after day 50. The main changes in the optical spectrum began at around that time. The He II 4686 Å line first appeared between days 7 and 14 and initially displayed a broad, symmetric profile that is characteristic of all species before day 60. The profile development thereafter depended on ionization state. Low-excitation lines remained comparatively narrow, with vrad,max of order 200-400 km s-1. They were systematically more symmetric than lines such as [Ca V], [Fe VII], [Fe X], and He II, all of which showed a sequence of profile changes going from symmetric to a blue wing similar to that of the low ionization species but with a red wing extended to as high as 600 km s-1. The [O I] 6300, 6364 doublet showed a narrow wind-emission component near the rest velocity of the system and a broad component, 200-300 km s-1, whose relative intensity increased in time. Forbidden lines of N II and O III had two separate contributors to the profiles, a broad line that increased in strength and velocity width, exceeding 200 km s-1, and narrow components from a surrounding ionized region at higher velocity than the Mira wind. The Na I D doublet developed a broad component with similar velocity width to the other low-ionization species. The O VI Raman features observed in recent outbursts of RS Oph were not detected. We interpret these variations as aspherical expansion of the ejecta within the Mira wind. The blue side is from the shock penetrating into the wind while the red wing is from the low-density periphery. The maximum radial velocities obey power laws, vmax ~ t - n with n ≈ 1/3 for red wing and ≈ 0.8 for the blue
The spectroscopic evolution of theγ-ray emitting classical nova Nova Mon 2012
No full textAims. Among the classical novae, the ONe subgroup, distinguished by their large overabundance of neon, are thought to occur on the most massive white dwarfs. Nova Mon 2012 was the first classical nova to be detected as a high energy γ-ray transient, by Fermi-LAT, before its optical discovery. The first optical spectra obtained about 55 days after γ-ray peak, were strikingly similar to the ONe class after the transition to the nebular (optically thin) spectrum. The current paper presents our subsequent optical and ultraviolet observations.
Methods. A time sequence of optical echelle spectra (3700–7400 Å) with the Nordic Optical Telescope (NOT) began on 2012 Aug. 16, immediately following the optical announcement, and are continuing. The nova was observed almost simultaneously with the NOT on 2012 Nov. 21, with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope at medium echelle resolution (1150–3050 Å) on Nov. 20, and with the CHIRON CTIO/SMARTS echelle spectrograph at medium resolution (4500–8900 Å) on Nov. 22. We used plasma diagnostics (e.g. [O III] and Hβ line flux) to constrain electron densities and temperatures, and the filling factor, for the ejecta. Using Monte Carlo modeling, we derived the structure from comparisons to the optical and ultraviolet line profiles. We also compared observed fluxes for Nova Mon 2012 with those predicted by photoionization modeling with Cloudy using element abundances derived for other ONe novae, the parameters derived from the line profile modeling and multiwavelength continuum measurements.
Results. Nova Mon 2012 is confirmed as an ONe nova first observed spectroscopically in the nebular stage. We derive an extinction of E(B − V) = 0.85 ± 0.05 and hydrogen column density NH ≈ 5 × 1021 cm-2. The corrected continuum luminosity is nearly the same in the entire observed energy range compared to V1974 Cyg, V382 Mon, and Nova LMC 2000 at the same epoch after outburst. The distance, about 3.6 kpc, is quite similar to V1974 Cyg, suggesting that it would have been equally bright had it been observed at maximum light. The same applies to the line profiles. These can be modeled using an axisymmetric conical – bipolar – geometry for the ejecta with various inclinations of the axis to the line of sight, i, and ejecta inner radii. For Nova Mon 2012, we find that 60 ≤ i ≤ 80 degrees, an opening angle of ≈70°, and an inner radius ΔR/R(t) ≈ 0.4 matches the permitted and intercombination lines while the forbidden lines require a less filled structure. The filling factor is f ≈ 0.1 − 0.3, although it may be lower based on the structures observed in the emission line profiles, implying an ejecta mass ≤ 6 × 10-5 M⊙. The abundances are similar to, but not identical to, V1974 Cyg and V382 Vel. In particular, Ne and Mg are apparently more abundant in Nova Mon 2012.
Conclusions. The ONe novae appear to comprise a single physical class with bipolar high mass ejecta, similarly enhanced abundances, and a common spectroscopic evolution within a narrow range of luminosities. The spectral evolution does not require continued mass loss from the post-explosion white dwarf. This also implies that the detected γ-ray emission is a generic phenomenon, common to all ONe novae, possibly to all classical novae, and connected with acceleration and emission processes within the ejecta
't Beloofde landt Canaan : doorwandelt van onsen Heere ende Salichmaecker Iesu Christo neffens syne Apostelen
No full textBeschreven in: Poortman en Augusteijn, Kaarten in bijbels p. 249 |
Van de kaart ontbreekt de linker helft |
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