1,724,073 research outputs found
Limits on the mass, velocity and orbit of PSR J1933-6211
No full textWe present a high-precision timing analysis of PSR J1933−6211, a millisecond pulsar with a 3.5 ms spin period and a white dwarf (WD) companion, using data from the Parkes radio telescope. Since we have accurately measured the polarization properties of this pulsar, we have applied the matrix template matching approach in which the times of arrival are measured using full polarimetric information. We achieved a weighted root-mean-square timing residuals of the timing residuals of 1.23 μs, 15.5 per cent improvement compared to the total intensity timing analysis. After studying the scintillation properties of this pulsar, we put constraints on the inclination angle of the system. Based on these measurements and on χ2 mapping we put a 2σ upper limit on the companion mass (0.44 M⊙). Since this mass limit cannot reveal the nature of the companion, we further investigate the possibility of the companion to be a He WD. Applying the orbital period-mass relation for such WDs, we conclude that the mass of a He WD companion would be about 0.26±0.01 M⊙, which combined with the measured mass function and orbital inclination limits, would lead to a light pulsar mass ≤ 1.0 M⊙. This result seems unlikely based on current neutron star formation models and we therefore conclude that PSR J1933−6211 most likely has a CO WD companion, which allows for a solution with a more massive pulsar
Misure di accelerazione con sensori MEMS interfacciati a una scheda di acquisizione NI-USB-6211
Get PDFLo scopo dell’attività di laboratorio descritta in questo elaborato è stato quello di realizzare un modulo dimostrativo per acquisizione e misure con dispositivi MEMS. Parte fondamentale è stata la realizzazione e il test del circuito di alimentazione e filtraggio per l’accelerometro memsic MXL2500ML. La scheda utilizzata è una National Instruments USB-6211, testata dapprima con una scheda di generazione di segnali. L’evoluzione della scheda realizzata viene utilizzata nel laboratorio di misure elettroniche come esperienza di acquisizione da dispositivi MEMSope
Mass measurements and 3D orbital geometry of PSR J1933–6211
No full textGeyer M, Krishnan VV, Freire PCC, et al. Mass measurements and 3D orbital geometry of PSR J19336211. Astronomy and Astrophysics. 2023;674: A169.PSR J1933−6211 is a pulsar with a spin period of 3.5 ms in a 12.8 d nearly circular orbit with a white dwarf companion. Its high proper motion and low dispersion measure result in such significant interstellar scintillation that detections with a high signal-to-noise ratio have required long observing durations or fortuitous timing. In this work, we turn to the sensitive MeerKAT telescope, and combined with historic Parkes data, are able to leverage the kinematic and relativistic effects of PSR J1933−6211 to constrain its 3D orbital geometry and the component masses. We obtain a precise proper motion magnitude of 12.42 (3) mas yr−1 and a parallax of 1.0 (3) mas, and we also measure their effects as secular changes in the Keplerian parameters of the orbit: a variation in the orbital period of 7 (1)×10−13 s s−1 and a change in the projected semi-major axis of 1.60 (5)×10−14 s s−1. A self-consistent analysis of all kinematic and relativistic effects yields a distance to the pulsar of kpc, an orbital inclination, i = 55 (1) deg, and a longitude of the ascending node, deg. The probability densities for Ω and i and their symmetric counterparts, 180 − i and 360 − Ω, are seen to depend on the chosen fiducial orbit used to measure the time of passage of periastron (T0). We investigate this unexpected dependence and rule out software-related causes using simulations. Nevertheless, we constrain the masses of the pulsar and its companion to be and 0.43 (5) M⊙, respectively. These results strongly disfavour a helium-dominated composition for the white dwarf companion. The similarity in the spin, orbital parameters, and companion masses of PSRs J1933−6211 and J1614−2230 suggests that these systems underwent case A Roche-lobe overflow, an extended evolutionary process that occurs while the companion star is still on the main sequence. However, PSR J1933−6211 has not accreted significant matter: its mass is still at ∼1.4 M⊙. This highlights the low accretion efficiency of the spin-up process and suggests that observed neutron star masses are mostly a result of supernova physics, with minimum influence of subsequent binary evolution
Mass measurements and 3D orbital geometry of PSR J19336211
Get PDFPSR J19336211 is a 3.5-ms pulsar in a 12.8-d orbit with a white dwarf
(WD). Its high proper motion and low dispersion measure result in such
significant interstellar scintillation that high signal-to-noise detections
require long observing durations or fortuitous timing. We turn to the sensitive
MeerKAT telescope and, combined with historic Parkes data, leverage PSR
J19336211's kinematic and relativistic effects to constrain its 3D orbital
geometry and the component masses. We obtain precise proper motion and parallax
estimates, and measure their effects as secular changes in the Keplerian
orbital parameters: a variation in orbital period of s
s and a change in projected semi-major axis of
s s. A self-consistent analysis of all kinematic and relativistic
effects yields a distance of kpc, an orbital inclination,
deg and a longitude of the ascending node, deg. The probability densities for and and their
symmetric counterparts, (, ), are seen to depend on the
fiducial orbit used to measure the time of periastron passage. We investigate
this unexpected dependence and rule out software-related causes using
simulations. Nevertheless, we constrain the pulsar and WD masses to
M and M respectively. These
strongly disfavour a helium-dominated WD. The orbital similarities between PSRs
J19336211 and J16142230 suggest they underwent Case A Roche lobe
overflow, an extended evolution while the companion star is still on the Main
Sequence. However, with a mass of M, PSR J19336211 has
not accreted significant matter. This highlights the low accretion efficiency
of the spin-up process and suggests that observed neutron star masses are
mostly a result of supernova physics.Comment: 16 pages, 7 figures. Abstract shortened to adhere to ArXiv limi
The Mass of PSR J1933-6211
No full textWe propose timing observations of the millisecond pulsar J1933-6211, which is likely to be the least heavy neutron star known. Measurement of its mass will have significant impact on supernova models, neutron star accretion efficiencies and neutron star formation scenarios. Following the observations of last term, we have now modelled the binary orbit sufficiently well to allow a significant Shapiro delay measurement in a small amount of (well planned) observing time. Previous observations indicate that the proposed 12 hours of observations will allow sufficient timing precision, notwithstanding the strongly scintillating character of this pulsar. ..
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mörike-Vertonungen aus der Schweiz. Musiques Suisses. (< [email protected] >). MGB CD 6211. TT : 55’ 45
No full textWeber Edith. Mörike-Vertonungen aus der Schweiz. Musiques Suisses. (). MGB CD 6211. TT : 55’ 45. In: Cahiers de sociologie économique et culturelle, n°49, 2010. pp. 123-124
Figurine en terre cuite d’Harpocrate au pot (IES-NI-6211)
No full textPar Cassandre Hartenstein, Université de Strasbourg, CNRS, UMR 7044 Archimède Abstract: publication of a terracotta figurine of god Harpokrates holding a pot. The piece, discovered in Tanis by Pierre Montet between WWI and WWII, is located in the Institute of Egyptology of the University of Strasbourg. [cite] Pdf : Hartenstein 2020, Harpocrate au pot IES-NI-6122_2_light Figure 1. Figurine en terre cuite d'Harpocrate au pot IES-NI-6211, vue de face. © Fr. Colin, Université de Strasbourg..
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