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Improbability of DUrca Process Constraints EOS

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Chinese Journal of Astronomy and Astrophysics 2007年第6期7卷 809-813页

作者： Hao Tong qiu-he peng Department of Astronomy Nanjing University Nanjing 210093

According to recent observational and theoretical progresses, the DUrca process （direct Urca process） may be excluded from the category of neutron star cooling mechanisms. This result, combined with the latest nuclear symmetry energy experiments, will provide us an independent way of testing the EOS （equation of state） for supernuclear density. For example, soft EOSs, such as FPS, will probably be excluded.

关键词： equation of state -- neutrinos -- stars neutron

Scale heights of Non-Edge-on Spiral Galaxies

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Chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 43-51页

作者： Tao Hu qiu-he peng Ying-he Zhao Department of Astronomy Nanjing University Nanjing 210093 Joint Astrophysics Center of Chinese Academy of Science-Peking University Beijing 100871 The Open Laboratory of Cosmic Ray and High Energy Astrophysics Chinese Academy of Sciences Beijing 100039

We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson＇s equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the ＂forbidden radius＂ r0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, peng ＆ Gu. Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.

关键词： galaxy: disk -- galaxies: fundamental parameters -- galaxies: spiral --galaxies: structure

Elliptical Galaxies with Emission Lines from the Sloan Digital Sky Survey

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Chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 15-24页

作者： Ying-he Zhao qiu-Sheng Gu Zhi-Xin peng Lei Shi Xin-Lian Luo qiu-he peng Department of Astronomy Nanjing University Nanjing 210093

As part of a study of star formation history along the Hubble sequence, we present here the results for 11 elliptical galaxies with strong nebular emission lines. After removing the dilution from the underlying old stellar populations by use of stellar population synthesis model, we derive the accurate fluxes of all the emission lines in these objects, which are then classified, using emission line ratios, into one Seyfert 2, six LINERs and four HII galaxies. We also identify one HII galaxy （A1216＋04） as a hitherto unknown Wolf-Rayet galaxy from the presence of the WolfRayet broad bump at 4650A. We propose that the star-forming activities in elliptical galaxies are triggered by either galaxy-galaxy interaction or the merging of a small satellite/a massive star cluster, as has been suggested by recent numerical simulations.

关键词： Galaxies: elliptical and lenticular cD Galaxies: starburst - Galaxies:individual: A1212+06 A1216+04 CGCG13-83 IC 225

The Inclination, Pitch Angle and Forbidden Radius of Spiral Arms of PGC 35105

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Chinese Journal of Astronomy and Astrophysics 2006年第2期6卷 175-180页

作者： Tao Hu Zheng-Yi Shao qiu-he peng Department of Astronomy Nanjing University Nanjing 210093 Shanghai Astronomical Observatory Chinese-Academy of Sciences Shanghai 200030 Joint Institute for Galaxies and Cosmology Chinese Academy of Sciences Shanghai 200030 Joint Astrophysics Center of Chinese Academy of Sciences-Peking University Beijing 100871 The Open Laboratory of Cosmic Ray and High Energy Astrophysics Chinese Academy otSciences Beijing 100049

We have studied some properties including surface brightness in the u, g, r, i, and z bands of the nearly face-on galaxy PGC 35105. By subtracting a model surface brightness distribution from the observed image we obtain the residual image that shows only the spiral arms freed from the contamination by the bulge. From this we measured the the inclination, pitch angle, and forbidden radius （identified with the innermost point of the arm） for each of the two arms; and that for each of the five observing bands. We found these three parameters are largely independent of the observing band.

关键词： galaxies: fundamental parameters - galaxies: spiral - galaxies: structure - galaxies: surface brightness - galaxies: individual (PGC 35105)

Sodium Enrichment in Yellow Supergiants:a Perspective from the Uncertainties of Reaction Rates

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Chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 700-706页

作者： Lei Zhao qiu-he peng Xin-Lian Luo Department of Astronomy Nanjing University Nanjing 210093 China

Sodium overabundance in yellow supergiants has stumped people for more than 20 years. The purpose of this paper is to explore this problem from the perspective of nuclear physics. We investigate carefully the CNO and NeNa cycles that are responsible for sodium production. We investigate some key reactions in the appropriate network. We show whether and how the sodium output can be affected by the rate uncertainties in these reactions. In this way, we evaluate if a reaction is important enough to deserve a better determination of its rate in terrestrial laboratories.

关键词： nuclear reactions nucleosynthesis stars: abundances supergiants

Disk Thicknesses and Some Parameters of 108 Non-Edge-On Spiral Galaxies

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Chinese Journal of Astronomy and Astrophysics 2007年第4期7卷 579-589页

作者： Tao Hu qiu-he peng Hong-Shi Zong Department of Astronomy Nanjing University Nanjing 210093 Department of Physics Nanjing University Nanjing 210093 Department of Physics and Electronics Zhangzhou Normal University Zhangzhou 363000 Joint Astrophysics Center of Chinese Academy of Sciences-Peking University Beijing 100871 Open Laboratory of Cosmic Ray and High Energy Astrophysics Chinese Academy of Sciences Beijing 100039

We present disk thicknesses, some other parameters and their statistics of 108 nonedge-on spiral galaxies. The method for determining the disk thickness is based on solving Poisson＇s equation for a disturbance of matter density in three-dimensional spiral galaxies. From the spiral arms found we could obtain the pitch angles, the inclination of the galactic disk, and the position of the innermost point （the forbidden region with radius r0 to the galactic center） of the spiral arm, and finally the thickness.

关键词： galaxy: disk- galaxies: fundamental parameters- galaxies: spiral - galaxies:structure

Microscopic Magnetic Dipole Radiation in Neutron Stars

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Chinese Journal of Astronomy and Astrophysics 2008年第3期8卷 269-276页

作者： Hao Tong qiu-he peng Hua Bai Department of Astronomy Nanjing University Nanjing 210093 China

There is a ^3P2 neutron superfluid region in NS （neutron star） interior. For a rotating NS the ^3P2 superfluid region is like a system of rotating magnetic dipoles. It will give out electromagnetic radiation, which may provide a new heating mechanism of NSs. This mechanism plus some cooling agent may give a sound explanation to NS glitches.

关键词： stars neutron -- pulsars general -- dense matter -- magnetic fields

A Spectroscopic Study of the SU UMa-type Dwarf Nova YZ Cnc during its 2002 Superoutburst

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Chinese Journal of Astronomy and Astrophysics 2005年第6期5卷 601-609页

作者： Ying-he Zhao Zong-Yun Li Xiao-An Wu qiu-he peng Department of Astronomy Nanjing University Nanjing 210093

We report on time-resolved spectroscopic observations of the SU Ursae Majoris dwarf nova, YZ Cnc for over llh on two nights during its 2002 January superoutburst. The spectra on the first day only showed absorption-line profiles, while on the second day the lines showed “W” profiles with blue and red troughs. The radial velocity curve of the absorption troughs and emission peaks of H/3 has an amplitude of 49±10 km s^-1 and a phase offset of -0.07±0.04, which are very similar to those measured in quiescence. However, the γ velocity deviates strongly from the systemic velocity measured in quiescence, by some ±60 km s^-1. Large shifts of -70 km s^-1 in the orbital-averaged velocity and -0.09 in the phase are also found in our observations. All these features can be well explained by a precessing, eccentric disk.

关键词： accretion, accretion disks -binaries close - novae, cataclysmic variables - stars dwarf novae - stars individual (YZ Cancri)

Measurements of the equivalent thicknesses of three-dimensional spiral galactic disks

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Research in Astronomy and Astrophysics 2009年第8期9卷 883-887页

作者： Gang Li Zhi-Quan Luo qiu-he peng Institute of Theoretical Physics China West Normal University Nanchong 637002 China Department of Astronomy Nanjing University Nanjing 210093 China

Spiral arms are fitted after the data from the latest spiral galactic images released by the Sloan Digital Sky Survey are processed. Equivalent thicknesses of 42 spiral galactic disks are derived, which increase the f... 详细信息

关键词： galaxies spiral -- Galaxy disk