{"title":"Properties of the He I 10830 Å Line in Solar Flares","authors":"Q. Du, Hui Li","doi":"10.1088/1009-9271/8/6/12","DOIUrl":"https://doi.org/10.1088/1009-9271/8/6/12","url":null,"abstract":"We study the properties of the He I 10830 A line in nine selected solar flares, using spectral data obtained with the Multi-channel Infrared Solar Spectrograph (MISS) at Purple Mountain Observatory (PMO) and photospheric images from the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). Our results indicate that, over an area of 3''– 8'', the He I 10830 A line shows emission exceeding the continuum in nearby quiet region when the Geostationary Operations Environmental Satellite (GOES) X-ray class of the flare reaches a threshold value (C4.5). The He I 10830 A line emission is detected only in the kernels of the Hα brightenings, but is not associated with the size of the flare. It is found that, whenever the He I 10830 A line shows excess emission over the nearby continuum both the Hα and the Ca II 8542 A lines display enhanced intensities exceeding their preflare intensities. The He I 10830 A line emission can occasionally extend into the umbra of the involved sunspot, which is inconsistent with previous studies. The weak component of He I 10830 A line changes from emission to absorption earlier than does the main component. Our results favor the photoionization-reconnection mechanism for the excitation of the He I 10830 A line.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128752157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Zhang, W. Bian, Chen Hu, Wei Mao, A. Luo, Yongheng Zhao
{"title":"Feedback of Active Galactic Nuclei in Seyfert 2 Galaxies","authors":"E. Zhang, W. Bian, Chen Hu, Wei Mao, A. Luo, Yongheng Zhao","doi":"10.1088/1009-9271/8/5/04","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/04","url":null,"abstract":"It is well accepted that feedback from active galactic nuclei (AGNs) plays an important role in the coevolution of the supermassive black hole (SMBH) and its host galaxy, but the concrete mechanism of feedback remains unclear. A considerable body of evidence suggests that AGN feedback suppresses star formation in the host galaxy. We assemble a sample of Seyfert 2 galaxies with recent observational data of compact nuclear starbursts and estimate the gas surface density as a function of column density to illuminate the relation between feedback and AGN properties. Although there are some uncertainties, our data still imply the deviation from the star formation law (Kennicutt-Schmidt law). Further, they indicate that: (1) Feedback correlates with the Eddington ratio, rather than with the mass of SMBH, as a result of decreasing star formation efficiency. (2) The SMBH and the torus are probably undergoing coevolution. Conclusions presented here can be refined through future high resolution CO or HCN observations.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114635383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Structural Properties of Early-Type Galaxies from the SDSS DR2","authors":"Fengshan Liu, Z. Deng, Hong Wu, X. Xia","doi":"10.1088/1009-9271/8/5/02","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/02","url":null,"abstract":"Two-dimensional bulge/disk light decomposition with GIM2D inboth the r- and g-bands has been applied to a sample of 129 early-type galaxies brighter than 13.5 magnitude in the r-band, selected from the Sloan Digital Sky Survey Data Release 2. Intensity-weighted Fourier coefficienta4/awas also derived for each sample galaxy. Our analysis shows that there are correlations between bulge-to-total light ratio (B/T) with bulge Sersic index n B and between bulge and disk scale sizes. Isophotal shape parametera 4/ais not correlated with B/T and nB. Both bulge and disk components satisfy a color-magnitude relation. The κ space Fundamental Plane analysis shows that galaxies with larger B/T tend to lie tighter and closer to the line of κ1 + κ2 =8 (the so-called \"zone of avoidance\") than the galaxies with smaller B/T. It indicates that existence of the disk component may lead to scatter of the distribution on the Fundamental Plane. Our analysis also shows that κ 1 + κ2 correlates with (g-r) color and B/T, but does not correlate witha 4/afor early-type galaxies. The fitted parameters and other retrieved parameters used in this paper for all sample galaxies are available online.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"177 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134137176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Vignetting Effect of a LAMOST-Type Schmidt Telescope","authors":"Yu-Lang Xue, Huoming Shi","doi":"10.1088/1009-9271/8/5/09","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/09","url":null,"abstract":"Optical vignetting of a Schmidt reflector is caused mainly by the spherical primary mirror not being big enough and by the effective light-collecting area of the corrector, which depends on the direction of the star light. Calculations of the vignetting of LAMOST, a special reflecting Schmidt telescope, are made by ray-tracing methods. The results show various features due to LAMOST's structure and observing modes. The un-vignetted field is small compared with its field of view. In the outmost portions of the field vignetting increases rapidly with the distance to the field center. The vignetting at a general position within the field of view is a function of both its distance to the field center and its position angle. Vignetting varies when the telescope points at different declinations and during observations. There is difference in vignetting between direct imaging and multi-fiber spectroscopy. Vignetting distorts the relative intensity of celestial objects at different positions in a field and also affects accurate sky-estimation and sky-subtraction. The determined vignetting functions may be used to correct the vignetting effect; alternatively flat-fielding may be adopted for the calibration. The effective apertures, which affect the signal-to-noise ratio of the observations, depend on the different declinations the telescope is pointing at and also different positions within a field due to vignetting.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"365 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133271720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Resolving the Mass Discrepancy between Strong and Weak Lensing Methods","authors":"Q. Zheng","doi":"10.1088/1009-9271/8/5/01","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/01","url":null,"abstract":"We readdress the outstanding cluster mass discrepancy between strong and weak gravitational lensing techniques utilizing updated data of both giant arcs and weak lensing measurements from the literature. We find that the systematically higher values of cluster masses revealed by strong lensing can be attributed to the oversimplification of the lensing model when estimating the cluster mass enclosed within the giant arcs. This arises because inhomogeneities and substructures in the central cores of clusters may invalidate the spherical symmetry assumption used widely in previous applications. When a more realistic modeling of the arcs is used, then the masses by strong lensing agree fairly well with those given by weak lensing when both are extrapolated to the same cluster regions. We conclude that as of now no significant discrepancy has been found among different cluster mass estimators including optical galaxies, X-ray gas and lensing.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128911237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Structure of the Galactic Halo","authors":"C. Du, Zhenyu Wu, Jun Ma, Xu Zhou","doi":"10.1088/1009-9271/8/5/07","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/07","url":null,"abstract":"We used the star counts in 21 BATC fields obtained with the National Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope to study the structure of the Galactic halo. Adopting a de Vaucouleurs r1/4 law halo, we found that the halo is somewhat flatter (c/a~0.4) towards the Galactic center than in the anticentre and antirotation direction ( 0.4$>c/a>0.4). We also notice that the axial ratios are smaller (flatter) towards the low latitude fields than the high latitude fields, except for a few fields. We provide robust limits on the large-scale flattening of the halo. Our analysis shows that the axial ratio of the halo may vary with distance and the observation direction. At large Galactocentric radii, the halo may not have a smooth density distribution, but rather, it may be largely composed of overlapping streams or substructures, which provides a support for the hybrid formation model.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125466841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Circumnuclear Star Forming Activity in NGC 3982","authors":"Shuinai Zhang, Q. Gu, Yi-Peng Wang","doi":"10.1088/1009-9271/8/5/06","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/06","url":null,"abstract":"We present a study of the nearby Seyfert galaxy NGC 3982 using optical, infrared and X-ray data acquired by SDSS, Spitzer and Chandra. Our main results are as follows: (1) A simple stellar population synthesis on the nuclear and circumnuclear SDSS spectra gives unambiguous evidence of young stellar components in both the nuclear and circumnuclear regions. (2) The Spitzer Infrared Spectrograph (IRS) spectrum of the central region (~3'') shows a power-law continuum, a silicate emission feature at 9.7 μm, and significant PAH emission features at 7.7, 8.6, 11.3 and 12.7 μm, suggesting the coexistence of AGN and starburst activities in the central region of NGC 3982. (3) We estimate the star formation rate (SFR) of the circumnuclear (~5''−20'') region from the Hα luminosity to be SFRHα = 0.52 M⊙ yr−1, which is consistent with the result from the Spitzer IRAC 8 μm luminosity, SFR8.0 μm = 0.57 M⊙ yr−1. (4) We measure the spectral energy distribution for the active nucleus of NGC 3982 from radio to X-ray, and obtain a bolometric luminosity of Lbol = 4.5×1042 erg s−1, corresponding to an Eddington ratio (Lbol/LEdd) of 0.014. The HST image of NGC 3982 shows a nuclear mini-spiral between the circumnuclear star-forming region and the nucleus, which could be the channel through which gas is transported to the supermassive black hole from the circumnuclear star-forming region.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"54 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131470795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. Shi, Xiao-Hui Sun, Jinlin Han, Xu-Yang Gao, Li Xiao
{"title":"Discovery of Three Large HII Regions in the Galactic Plane","authors":"W. Shi, Xiao-Hui Sun, Jinlin Han, Xu-Yang Gao, Li Xiao","doi":"10.1088/1009-9271/8/5/08","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/08","url":null,"abstract":"We discovered three large HII regions: G148.8+2.3, G149.5+0.0 and G169.9+2.0 in the Sino-German λ 6 cm polarization survey of the Galactic plane. They have been identified based on the flat spectral indexes and the strong infrared emission properties.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127936902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Extragalactic H2O Megamaser Sources: Central Black Holes, Nuclear X-ray and Maser Emissions ∗","authors":"Jiang-Bo Su, Jiangshui Zhang, J. Fan","doi":"10.1088/1009-9271/8/5/05","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/05","url":null,"abstract":"Extragalactic H2O megamasers are typically found within the innermost few parsecs of active galaxy nuclei (AGN) and the maser emission is considered to be excited most likely by the X-ray irradiation of the AGN. We investigate a comprehensive sample of extragalactic H2O masers in a sample of 38 maser host AGN to check potential correlations of the megamaser emission with parameters of the AGN, such as X-ray luminosity and black hole (BH) masses. We find a relation between the maser luminosities and BH masses, LH2O∝MBH3.6±0.4, which supports basically the theoretical prediction. The relation between the maser emission and X-ray emission is also confirmed.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123392421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Application of Accelerometer Data in Precise Orbit Determination of GRACE -A and -B ∗","authors":"D. Peng, Bin Wu","doi":"10.1088/1009-9271/8/5/11","DOIUrl":"https://doi.org/10.1088/1009-9271/8/5/11","url":null,"abstract":"We investigate how well the GRACE satellite orbits can be determined using the on-board GPS data combined with the accelerometer data. The preprocessing of the accelerometer data and the methods and models used in the orbit determination are presented. In order to assess the orbit accuracy, a number of tests are made, including external orbit comparison, and through Satellite Laser Ranging (SLR) residuals and K-band ranging (KBR) residuals. It is shown that the standard deviations of the position differences between the so-called precise science orbits (PSO) produced by GFZ, and the single-difference (SD) and zero-difference (ZD) dynamic orbits are about 7 cm and 6 cm, respectively. The independent SLR validation indicates that the overall root-mean-squared (RMS) errors of the SD solution for days 309-329 of 2002 are about 4.93 cm and 5.22 cm, for GRACE-A and B respectively; the overall RMS errors of the ZD solution are about 4.25 cm and 4.71 cm, respectively. The relative accuracy between the two GRACE satellites is validated by the KBR data to be on a level of 1.29 cm for the SD, and 1.03 cm for the ZD solution.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123898860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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