An orbital period analysis of the dwarf novae OY Carinae     

《New Astronomy》2015

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Multiwavelength modeling the SED of supersoft X-ray sources III. RS Ophiuchi: The supersoft X-ray phase and beyond     

《New Astronomy》2015

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New intrinsic-colour calibration for uvby-β photometry     

Yüksel Karataş  William J. Schuster 《New Astronomy》2010,15(5):444-449

A new intrinsic-colour calibration $((b-y{)}_o-\beta )$ is presented for the uvby-β photometric system, making use of re-calibrated Hipparcos parallaxes and published reddening maps. This new calibration for $(b-y{)}_o-\beta$, our Eq. (1), has been based upon stars with $d_{\mathit{Hip}}<70\text{pc}$ in the photometric catalogues of Schuster and Nissen (1988), Schuster et al., 2004, Schuster et al., 2006, provides a small dispersion, $\pm 0.009$, and has a positive “standard” $+2.239\mathrm{\Delta }\beta$ coefficient, which is not too different from the coefficients of Crawford (1975a, +1.11) and of Olsen (1988, +1.34). For 61 stars with spectra from CASPEC, UVES/VLT, and FIES/NOT databases, without detectable Na I lines, the average reddening value $〈E(b-y)〉=-0.001\pm 0.002$ shows that any zero-point correction to our intrinsic-colour equation must be minuscule.  相似文献   

A period study and revised photometric model for the eclipsing binary ZZ Cyg     

《New Astronomy》2015

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Accurate absolute parameters of the binary system V4089 Sgr     

《New Astronomy》2015

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KIC 9851142: A binary star with total eclipses and γ Dor pulsations     

《New Astronomy》2015

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Six observations consistent with the electron neutrino being a m2=-0.11±0.02eV2 tachyon     

《Astroparticle Physics》2015

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Absolute and geometric parameters of the W UMa type contact binary V546 And     

《New Astronomy》2015

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Absolute and geometric parameters of contact binary BO Arietis     

《New Astronomy》2015

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A cool stellar companion to the δ Scuti variable star GW UMa     

《New Astronomy》2015

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Charged dilation black holes as particle accelerators     

《Astroparticle Physics》2015

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Absolute parameters of the newly-identified contact binary star IS Canis Major     

B. Özkardeş  A. Erdem 《New Astronomy》2010,15(2):247-253

This paper presents the results of the first high-resolution spectroscopic observations of the Southern W UMa type system IS CMa. Spectroscopic observations of the system were made at Mt. John University Observatory using a HERCULES fibre-fed échelle spectrograph in September 2007. The first radial velocities of the component stars of the system were determined by using the spectral disentangling technique. The resulting orbital elements of IS CMa are: $a_1\sin i=0.0041\pm 0.0001$ AU, $a_2\sin i=0.0135\pm 0.0001$ AU, $M_1{\sin }^{3}i=1.48\pm 0.01{\mathrm{M}}_{\odot }$, and $M_2{\sin }^{3}i=0.44\pm 0.01{\mathrm{M}}_{\odot }$. The components were found to be in synchronous rotation taking into account the disentangled ${\mathrm{H}}_{\delta }$ line profiles of both components of the system. The Hipparcos light curve was solved by means of the Wilson–Devinney method supplemented with a Monte Carlo type algorithm. The radial velocity curve solutions including the proximity effects give the mass ratio of the system as 0.297 ± 0.001. The combination of the Hipparcos light and radial velocity curve solutions give the following absolute parameters of the components: $M_1=1.68\pm 0.04{\mathrm{M}}_{\odot }\text{,}{\mathrm{M}}_2=0.50\pm 0.02{\mathrm{M}}_{\odot }\text{,}{R}_1=2.00\pm 0.02{\mathrm{R}}_{\odot }\text{,}{R}_2=1.18\pm 0.03R_{\odot }\text{,}{L}_1=7.65\pm 0.60$ ${\mathrm{L}}_{\odot }$ and $L_2=1.99\pm 0.80{\mathrm{L}}_{\odot }$. The distance to IS CMa was calculated as $87\pm 5$ pc using the distance modulus with corrections for interstellar extinction. The position of the components of IS CMa in the HR diagram are also discussed: the system seems to have an age of 1.6 Gyr.  相似文献   

Classical implicit travelling wave solutions for a quasilinear convection–diffusion equation     

Jessica Hearns  Robert A. Van Gorder 《New Astronomy》2012,17(8):705-710

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Multifractal properties of solar filaments and sunspots numbers     

《New Astronomy》2015

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Constraints on the tidal dissipation factor of a main sequence star: The case of OGLE-TR-56b     

《Planetary and Space Science》2007,55(5):643-650

The planet OGLE-TR-56b is the extrasolar giant planet closest to its host star. This planet and its star exchange extreme tidal forces. This leads to a reduction of the planetary orbit and a spin-up of the stellar rotation. The tidal migration rate depends crucially on the ratio of the tidal dissipation factor $Q_{*}$ and the stellar love number $k_{2{,}^{*}}$of the star, which is only poorly known and estimates range within $5\times 10^5<(Q_{*}/k_{2^{*}})<10^{10}$. For values greater than $Q_{*}/k_{2^{*}}>1.5\times 10^9$no observable influence by tidal forces on the planet's orbit within the lifetime for the star can be found. A lower limit for the possible values of the parameter $Q_{*}/k_{2^{*}}$for the G-type star OGLE-TR-56 was found by studying the evolution of possible tidal interaction into the future and in the past. This study demonstrates that on the basis of conservative model assumptions, a considerable but unrealistic spin-up of the star can be expected if $Q_{*}/k_{2^{*}}<2\times 10^7$, which is not in agreement with observed stellar rotation periods. From a statistical analysis based on a Monte-Carlo tidal evolution simulation, the $Q_{*}/k_{2^{*}}$ parameter can be constrained to the range $2\times 10^7<Q_{*}/k_{2^{*}}<1.5\times 10^9$ if the system shall evolve significantly and realistically by tidal forces.  相似文献   

The effect of a thin weak layer covering a basalt block on the impact cratering process     

Koji Dohi  Masahiko Arakawa  Chisato Okamoto  Sunao Hasegawa  Minami Yasui 《Icarus》2012,218(2):751-759

To clarify the effect of a surface regolith layer on the formation of craters in bedrock, we conducted impact-cratering experiments on two-layered targets composed of a basalt block covered with a mortar layer. A nylon projectile was impacted on the targets at velocities of 2 and 4 km s^?1, and we investigated the crater size formed on the basalt. The crater size decreased with increased mortar thickness and decreased projectile mass and impact velocity. The normalized crater volume, π_V, of all the data was successfully scaled by the following exponential equation with a reduction length λ₀: ${\pi }_{\text{V}}=b_0{\pi }_{\text{Y}}^{-b_1}\exp (-\lambda /{\lambda }_0)$, where λ is the normalized thickness T/L_p, T and L_p are the mortar thickness and the projectile length, respectively, b₀ and b₁ are fitted parameters obtained for a homogeneous basalt target, 10^?2.7±0.7 and ?1.4 ± 0.3, respectively, and λ₀ is obtained to be 0.38 ± 0.03. This empirical equation showing the effect of the mortar layer was physically explained by an improved non-dimensional scaling parameter, ${\pi }_{\text{Y}}^1$, defined by ${\pi }_{\text{Y}}^1=Y/({\rho }_{\text{t}}{u}_{\text{p}}^2)$, where u_p was the particle velocity of the mortar layer at the boundary between the mortar and the basalt. We performed the impact experiments to obtain the attenuation rate of the particle velocity in the mortar layer and derived the empirical equation of $\frac{u_{\text{p}}}{v_{\text{i}}}=0.50\exp \left(-\frac{\lambda }{1.03}\right)$, where v_i is the impact velocity of the projectile. We propose a simple model for the crater formation on the basalt block that the surface mortar layer with the impact velocity of u_p collides on the surface of the basalt block, and we confirmed that this model could reproduce our empirical equation showing the effect of the surface layer on the crater volume of basalt.  相似文献   

Dark neutrinos as Cold Dark Matter     

《Astroparticle Physics》2015

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A W UMa type system from Southern Hemisphere: CN Hydri     

B. Özkardeş  A. Erdem  V. Bakış 《New Astronomy》2009,14(5):461-466

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Young eccentric binary KL CMa revisited in the light of spectroscopy     

《New Astronomy》2015

The absolute dimensions of the components of the eccentric eclipsing binary KL CMa have been determined. The solution of light and radial velocity curves of high ($\mathrm{\Delta }\lambda =0.14$ Å) and intermediate ($\mathrm{\Delta }\lambda =1.1$ Å) resolution spectra yielded masses M₁ = 3.55 ± 0.27 M_⊙, M₂ = 2.95 ± 0.24 M_⊙ and radii R₁ = 2.37 ± 0.09 R_⊙, R₂ = 1.70 ± 0.1 R_⊙ for primary and secondary components, respectively. The system consists of two late B-type components at a distance of 220 ± 20 pc for an estimated reddening of $E(B-V)=0.127$.The present study provides an illustration of spectroscopy’s crucial role in the analysis of binary systems in eccentric orbits. The eccentricity of the orbit ($e=0.20$) of KL CMa is found to be bigger than the value given in the literature ($e=0.14$). The apsidal motion rate of the system has been updated to a new value of $\dot{w}=0°.0199\pm 0.0002{\text{cycle}}^{-1}$, which indicates an apsidal motion period of $U=87\pm 1$ yrs, two times slower than given in the literature. Using the absolute dimensions of the components yielded a relatively weak relativistic contribution of ${\dot{w}}_{\mathit{rel}}=0°.0013{\text{cycle}}^{-1}$. The observed internal-structure component ($\log k_{2\text{,}\mathit{obs}}=-2.22\pm 0.01$) is found to be in agreement with its theoretical value ($\log k_{2\text{,}\mathit{theo}}=-2.23$).Both components of the system are found very close to the zero-age main-sequence and theoretical isochrones indicate a young age ($\tau =50$ Myr) for the system. Analysis of the spectral lines yields a faster rotation ($V_{\mathit{rot}1\text{,}2}=100$ km s⁻¹) for the components than their synchronization velocities ($V_{\mathit{rot}\text{,}\mathit{syn}1}=68$ km s⁻¹, $V_{\mathit{rot}\text{,}\mathit{syn}1}=49$ km s⁻¹).  相似文献   

An interacting O + O supergiant close binary system: Cygnus OB2-5 (V729 Cyg)     

《New Astronomy》2014

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