2004, Vol.4, No.5 (October 20, 2004)


Contents

LETTER
  • Discovery of Three Variable Stars in Direction toward NGC 4565    p.411
    Lei Li, Hong Wu, Xiao-Bin Zhang, Ya-Bo Wu, Xu Zhou, Zhao-Ji Jiang and Jun Ma  
    Abstract | | PDF file (246 KB) | PS file *.gz  (863 KB) 
RESEARCH PAPERS
Extragalactic Astronomy
  • SDSS J022119.84+005628.4: A Radio-Loud Narrow-Line Seyfert 1 Galaxy with
    Star Formation in its Nucleus        p.415
    Jing Wang, Jian-Yan Wei and Xiang-Tao He  
    Abstract | | PDF file (248 KB) | PS file *.gz  (248 KB) 
  • Chandra  Observations of the Flat Spectrum Seyfert-2 Galaxies NGC 2110 and NGC 7582    p.427
    Hui Dong, Sui-Jian Xue, Cheng Li and Fu-Zhen Cheng  
    Abstract | | PDF file (303 KB) | PS file *.gz  (519 KB) 
Stars
  • Molecular Gas and Dust in the Massive Star Forming Region S 233 IR    p.440
    Rui-Qing Mao and Qin Zeng 
    Abstract | | PDF file (1560 KB) | PS file *.gz  (500 KB) 
  • Afterglow Light Curves of Jetted Gamma-ray Burst Ejecta in Stellar Winds   p.455
    Xue-Feng Wu, Zi-Gao Dai, Yong-Feng Huang and Hai-Tao Ma
     Abstract | | PDF file (440 KB) | PS file *.gz  (769 KB)  
The Sun
  • Visible and Near-Infrared Contrast of Faculae in Active Region NOAA 8518   p.481
    Yan Xu, Guo Yang, Jiong Qiu, Tom J. Spirock, Ju Jing, Carsten Denker and Haimin Wang
     Abstract | | PDF file (381 KB) | PS file *.gz  (993 KB)  
  • Corrections to Solar Thermal Structure when a Turbulent Magnetic Field is Included   p.490
    Yi Liao and Shao-Lan Bi
     Abstract | | PDF file (186 KB) | PS file *.gz  (201 KB)  
Astrometry and celestial mechanics
  • The Q Values of the Galilean Satellites and their Tidal Contributions to the Deceleration of Jupiter's Rotation   p.499
    Hong Zhang and Cheng-Zhi Zhang
     Abstract | | PDF file (160 KB) | PS file *.gz  (60 KB)  

 


Abstract

 


Discovery of Three Variable Stars in Direction toward NGC 4565 

Lei Li (1,2,3), Hong Wu (1), Xiao-Bin Zhang (1), Ya-Bo Wu (3), Xu Zhou (1), Zhao-Ji Jiang (1) and Jun Ma  (1) 

Affiliation:    (1) National Astronomical Observatories, CAS (NAOC), Beijing 100012, China
                     (2) Department of Mathematics and Physics, Dalian Maritime University, Dalian 116026
                     (3) Department of Physics, Liaoning Normal University, Dalian 116029
 
E-mail:    hwu@bao.ac.cn   (corresponding author);  ll-meteor@163.com   

Abstract

We present the results of a variable star search in a field next to the edge-on galaxies NGC~4565 from the archive data of Beijing-Arizona-Taibei-Connecticut Multicolor Sky Survey. Three new variable stars were discovered. Based on spectra obtained from the 2.16m NAOC telescope, we identify two of these as RR Lyr stars and one as a special T Tauri star.

Key words: stars: variables: RR Lyr --- stars: variables: T Tauris

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SDSS J022119.84+005628.4: A Radio-Loud Narrow-Line Seyfert 1 Galaxy with Star Formation in its Nucleus 

Jing Wang (1,2), Jian-Yan Wei (2) and Xiang-Tao He (1)

 Affiliation:   (1)  Department of Astronomy, Beijing Normal University, Beijing 100875
                    (2)  National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

E-mail:   wj@bao.ac.cn     (corresponding author)

Abstract

The optical spectrum of SDSS J022119.84 + 005628.4 (RA = 02h21m19.84 s,
Dec = 00o56' 28".4, J2000; z=0.399785 ± 0.000558) is analyzed by multi-component profile modelling. The small flux ratio of  [O III]NC/H $\beta$ (=0.78) and $\rm {FWHM}(\rm {H}\beta_{\rm {BC}})=\rm {1778.1\pm 85.9\ km\ s^{-1}}$ led us to identify SDSS J022119.84 + 005628.4 as a Narrow-line Seyfert 1 galaxy with RFe=1.4+1.0-1.0 and intermediate radio loudness, log R =1.93. The continuum low jump at the Balmer limit might be contributed by a starburst component, which suggests that the object is a relatively young AGN with star-formation activity in its inner region. This provides a useful observational test of the AGN evolution. The low flux ratio of the narrow components, $[\rm {\ion{O}{iii}}]/\rm {H}\beta = 1.62$, and the prominent [\ion{O}{ii}]$\lambda$3727 emission, [\ion{O}{ii}]/[\ion{O}{iii}] = 2.24, suggests that there should be a group of AGNs different from Seyfert 2s when their broad line regions are obscured by the torus on the line of sight. A possible orientation effect is suggested to interpret the observed Seyfert 1.5s-like spectrum of the object. The spectrum features prominent broad blue wings of both [\ion{O}{iii}] $\lambda\lambda$4959 and 5007. After excluding other possible contributions, we conclude that the broad components are emitted by [\ion{O}{iii}] itself. The material emitting the broad [\ion{O}{iii}] line is probably situated in a transient line region (with a low electron density, ne < 107 cm-3) between the broad line region (BLR) and the narrow line region (NLR). The object can be classified as a ``blue outlier'' defined by Zamanov et al., according to its velocity shift $\upsilon_r \rm {([\ion{O}{iii}])=-293.6\pm18.0\ km\ s^{-1}}$, relative to the systematic velocity.

Key words:  galaxies: active --- galaxies: Seyfert --- quasars: individual (SDSS J022119.84 + 005628.4)
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Chandra Observations of the Flat Spectrum Seyfert-2 Galaxies NGC 2110 and NGC 7582

Hui Dong (1), Sui-Jian Xue (2), Cheng Li (1) and Fu-Zhen Cheng (1)

 Affiliation:    (1)  Center for Astrophysics, University of Science and Technology of China, Hefei 230026; donghui@mail.ustc.edu.cn
                     (2)  National Astronomical Observatories, CAS (NAOC), Beijing 100012, China
               
E-mail:  donghui@mail.ustc.edu.cn   (corresponding author)

Abstract

Chandra observations of the Seyfert-2 galaxies NGC 2110 and NGC 7582 are presented. With the superb spatial resolution of  Chandra we found that in NGC 7582 the soft ($\leq$2 keV) and hard (2--10 keV) X-rays are emitted in different regions, consistent with the report by Xue et al.  By comparing the present X-ray data with the previous infrared data, we determined that the soft X-ray region is the site of starburst activities. We found no significant temporal variations during our observations. We confirm the previous finding that NGC 2110 and NGC 7582 are flat-spectrum sources. We argue that the flat spectra may result from a cold absorbing material such as envisaged in the ``dual absorbed" model. Strong Fe K$\alpha$ emission feature is detected in 6$\sim$7 keV. Its equivalent width is so large that it cannot be reproduced by using the Galactic column density of $\sim$1022 cm-2.

Key words:  X-rays: image --- X-ray: spectrum --- Galaxy: Seyfert --- Galaxy: individuals: NGC 7582 and NGC 2110

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Molecular Gas and Dust in the Massive Star Forming Region S 233 IR

Rui-Qing Mao (1,2) and Qin Zeng (1)

 Affiliation:    (1)  Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 
                     (2)  National Astronomical Observatories, CAS (NAOC), Beijing 100012, China
                   
E-mail:    rqmao@jets.pmo.ac.cn   
Abstract

The massive star forming region S 233 IR is observed in the molecular lines CO J = 2--1, 3--2, \AMM\,(1,1), (2,2) and the 870 um dust continuum. Four submillimeter continuum sources, labelled SMM\,1--4, are revealed in the 870 um dust emission. The main core, SMM1, is found to be associated with a deeply embedded near infrared cluster in the northeast; while the weaker source SMM2 coincides with a more evolved cluster in the southwest. The best fit spectral energy distribution of SMM1 gives an emissivity of $\beta$=1.6, and temperatures of 32 K and 92 K for the cold-- and hot--dust components. An SMM1 core mass of 246 $M_{\odot}$, and a total mass of 445 $M_{\odot}$ are estimated from the 870 um dust continuum emission. SMM1 is found to have a temperature gradient decreasing from inside out, indicative of the presence of interior heating sources. The total outflow gas mass as traced by the CO J = 3--2 emission is estimated to be 35 $M_{\odot}$. Low velocity outflows are also found in the \AMM\,(1,1) emission. The non-thermal dominant \AMM\ line width as well as the substantial core mass suggest that the SMM1 core is a $``$turbulent, massive dense core", in the process of forming a group or a cluster of stars. The much higher star formation efficiency found in the southwest cluster supports the suggestion that this cluster is more evolved than the northeast one. Large near infrared photometric variations found in the source PCS--IR93, a previously found highly polarized nebulosity, indicate an underlying star showing the FU Orionis type of behavior.

Key words:  ISM: jets and outflows --- ISM: molecules --- ISM: dust, extinction --- stars: formation --- ISM: individual (IRAS 05358+3543; S 233 IR)

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Afterglow Light Curves of Jetted Gamma-ray Burst Ejecta in Stellar Winds
Xue-Feng Wu, Zi-Gao Dai, Yong-Feng Huang and Hai-Tao Ma

Affiliation:   Department of Astronomy, Nanjing University, Nanjing 210093

E-mail:    xfwu@nju.edu.cn   (corresponding author)
  
Abstract

Optical and radio afterglows arising from shocks by relativistic conical ejecta running into pre-burst massive stellar winds are revisited. Under the homogeneous thin-shell approximation and a realistic treatment for the lateral expansion of jets, our results show that a notable break exists in the optical light curve in most cases we calculated in which the physical parameters are varied within reasonable ranges. For a relatively tenuous wind which cannot decelerate the relativistic jet to cause a light curve break within days, the wind termination shock due to the ram pressure of the surrounding medium occurs at a small radius, namely, a few times 1017 cm. In such a structured wind environment, the jet will pass through the wind within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallower drop after the jet encounters the uniform medium, and then declines deeply, triggered by runaway lateral expansion.

Key words:   hydrodynamics --- relativity --- shock waves --- gamma-rays: bursts

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X-ray Flashes from Off-axis Nonuniform Jets

Zhi-Ping Jin and Da-Ming Wei
Affiliation:    Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008; 
                     National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012
                    
E-mail:     jin@pmo.ac.cn    (corresponding author)

Abstract

It has been widely believed that the outflows in gamma-ray bursts are jetted and some jets may have structures like $\epsilon(\theta)\propto\theta^{-k}$. We check the possibility that X-ray flashes come from such jets. Both qualitative and quantitative analyses have shown that this model can reproduce most of the observational features of both X-ray flashes and gamma-ray bursts. Using the usual parameters of gamma-ray bursts, we have carried out numerical calculations for both uniform and nonuniform jets, of their fluxes, spectra and peak energies. It seems that nonuniform jets are more appropriate to these observational properties than uniform jets. We have also shown that in our model the observational ratio of gamma-ray bursts to X-ray flashes is about a few units.

Key words:  X-rays: general --- gamma rays: bursts --- ISM: jets and outflows

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Visible and Near-Infrared Contrast of Faculae in Active Region NOAA 8518

Yan Xu, Guo Yang, Jiong Qiu, Tom J. Spirock, Ju Jing, Carsten Denker and Haimin Wang

 Affiliation:    Center for Solar-Terrestrial Research, New Jersey Institute of  Technology 323 Martin Luther King Blvd, Newark, NJ 07102, USA; 

E-mail:  yx2@njit.edu    (corresponding author)

Abstract

We compare the contrast of faculae, in visible light and in the near infrared (NIR), that were associated with the active region NOAA 8518 which crossed the solar disk from April 19 to 27, 1999. We obtained NIR continuum images at 1.6 um at the Big Bear Solar Observatory (BBSO) with an Indium Gallium Arsenide (In Ga As) NIR digital camera. We also obtained high-resolution longitudinal magnetograms and visible light filtergrams at 610.3 nm with the newly developed Digital Vector Magnetograph (DVMG). Our data show that the contrast of faculae has the same sign in both the visible and the NIR. We did not find any so-called ``dark faculae", faculae that are bright in the visible and simultaneously dark in the NIR. We determined a threshold magnetic flux density that separates pores from faculae.

Key words:  Sun: infrared --- Sun: faculae

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Corrections to Solar Thermal Structure when a Turbulent Magnetic Field is Included

Yi Liao and Shao-Lan Bi

Affiliation:     National Astronomical Observatories, Yunnan Observatory, Kunming 650011 
                    
E-mail:     liaoyi23@yahoo.com.cn    (corresponding author)

Abstract

Correction of non-ideal effect due to a magnetic fluctuating tensor is derived from the ideal MHD equations. The inclusion of a magnetic turbulent field leads to modifications of the hydrostatic equilibrium equation and thermodynamical variables such as the temperature T, the adiabatic exponent $\gamma$, the adiabatic temperature gradient $\nabla_{\rm ad}$ and the temperature gradient $\nabla$. In particular, the modifications in the adiabatic and radiative temperature gradients will result in a change in the Schwarzchild criterion, hence in the location of the base of the convective zone. Incorporating the modifications, we construct a modified thermodynamical equilibrium structure of the Sun.

Key words:   solar convection --- MHD: thermodynamics variables --- Sun: hydrostatic equilibrium equation

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The Q Values of the Galilean Satellites and their Tidal Contributions to the Deceleration of Jupiter's Rotation
Hong Zhang and Cheng-Zhi Zhang

 Affiliation:  Department of Astronomy, Nanjing University, Nanjing 210093
                    
E-mail:   zhangh@nju.edu.cn    (corresponding author)

Abstract

The relationship between the k2/Q of the Galilean satellites and the k2J/QJ of Jupiter is derived from energy and momentum considerations. Calculations suggest that the Galilean satellites can be divided into two classes according to their Q values: Io and Ganymede have values between 10 and 50, while Europa and Callisto have values ranging from 200 to 700. The tidal contributions of the Galilean satellites to Jupiter's rotation are estimated. The main deceleration of Jupiter, which is about 99.04% of the total, comes from Io.
Key words:  Sun: prominences --- line: profiles --- turbulence

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ChJAA, 2004, Vol.4, No.5

Chinese Journal of Astronomy and Astrophysics: Online Edition

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