Zhenlong Zou

Chinese Academy of Sciences | CAS · National Astronomicl Observatory

The edge-on, nearby spiral galaxy NGC 5907 has long been used as the prototype of a "noninteracting" warped galaxy. We report here the discovery of two interactions with companion dwarf galaxies that substantially change this picture. First, a faint ring structure is discovered around this galaxy that is likely due to the tidal disruption of a comp...

In this paper we present a multicolor photometric study of the nearby spiral galaxy M81, using images obtained with the Beijing Astronomical Observatory 60/90 cm Schmidt telescope in 13 intermediate-band filters from 3800 to 10000 Å. The observations cover the whole area of M81, with a total integration of 51 hr from 1995 to 1997 February. This pro...

We present optical candidates for 75 X-ray sources in a ~1 deg2 overlapping region with the 1997 medium-deep ROSAT survey by Molthagen et al. These candidates are selected using the multicolor CCD imaging observations made for the T329 field of the Beijing-Arizona-Taiwan-Connecticut (BATC) Sky Survey, which uses the NAOC 0.6/0.9 m Schmidt telescope...

We present optical candidates for 75 X-ray sources in a $\sim 1$ deg$^2$ overlapping region with the medium deep ROSAT survey. These candidates are selected using the multi-color CCD imaging observations made for the T329 field of the Beijing-Arizona-Taipei-Connecticut (BATC) Sky Survey. These X-ray sources are relatively faint (CR $<< 0.2 s^{-1}$)...

It is an introductory remark of our knowledge frontier about objects in the distant as well as in the local universe. Attention is focused on high z galaxies and exoplanets: their discovery methods, progress and some future plans.

We discussed the physical background of the unified scaling law in spiral galaxies, and qualitatively obtained the power index of an empirically relationship between the luminosity L, radius R and the rotation velocity V. We found from I-band data that the relation of L ~ V2R can minimize the Tully-Fisher residuals.

We present a deep, 42.79 hr image of the nearby, edge-on galaxy NGC 4565 in the Beijing-Arizona-Taipei-Connecticut 6660 Angstrom band using the large-format CCD system on the 0.6 m Schmidt telescope at the Xinglong Station of the National Astronomical Observatories of China. Following the procedures previously developed by our team for the analysis...

The fundamental plane of spiral galaxies was searched from observational data, which can be approximately represented in observational parameters by $ L \propto V^2 R $, where $L$, $R$, and $V$ are the luminosity, the linear size of galactic disk, and the rotation velocity. This plane exists at all optical bands in our samples of more than 500 spir...

Using photometric criterion and incorporating the global morphologies, we separated nuclei from bright star cluster associations based on an ultraluminous infrared galaxies (ULIRGs) image sample provided by HST snapshot image survey. The result supports the multi-merger as a way to form elliptical galaxies through ULIRGs phase. Comparing with the o...

We perform photometric measurements on a large HST snapshot imaging survey sample of 97 ultraluminous infrared galaxies (ULIRGs). We select putative nuclei from bright clumps in all the sample targets, mainly based on a quantitative criterion of I-band luminosity as well as the global and local morphological information. All the sources are then cl...

We report the evidence for the existence of the fundamental plane of spiral galaxies, which can be represented in observable terms by the absolute magnitude, the linear size of galactic disk and the rotation velocity. This fundamental plane exists at all optical bands, and can reduce the residual of the Tully-Fisher relations by more than 50%.

Strong Mg II quasar absorption line systems provide us with a useful tool to understand the gas that plays an important role in galaxy formation. In this paper, placing the theories of galaxy formation in a cosmological context, we present semi-analytic models and Monte-Carlo simulations for strong Mg II absorbers produced in gaseous galactic haloe...

The ultra-luminous IRAS galaxies (ULIRGs) are strong interacting or merging galaxies. There is also the evidence both from observational and theoretical sides that the remnants of merger could be ellipticals. However, it is not clear that these merging remnants ellipticals are from major merger of two spiral galaxies or from multi-merger of group o...

We describe in detail the extinction correction procedures used for the Beijing-Arizona-Taiwan-Connecticut Sky Survey (BATC Survey). The survey covers the spectral range 3200-9900 Å by utilizing a set of 15 intermediate-band filters. These filters are specifically designed to exclude most of the bright and variable night-sky emission lines. We also...

We present an optical spectrum for Mrk 273x, the X-ray source 1.3' to the northeast of Mrk 273. The new spectrum indicates that the object is at a much higher redshift (0.458) than the value previously reported by us (0.0376). All the detected emission lines show properties of Seyfert 2 galaxies. Mrk 273x has one of the highest X-ray and radio lumi...

We study the surface photometry for 13 single-nucleus ultraluminous IRAS galaxies (ULIRGs), selected from a parent sample of 58 galaxies obtained in a Hubble Space Telescope snapshot survey. We find that these galaxies can be classified into three classes according to their surface photometry. The surface brightness profiles of the four objects in...

We have completed spectroscopic observations (Wu et al. 1997a) of a sample of 73 very luminous infrared galaxies (log(IR/L☉) ≥ 11.5;H 0 = 50 km s-1 Mpc-1) from the 2-Jy catalogue (Strauss et al. 1992) using the 2.16m telescope at the Beijing Astronomical Observatory. Spectral and interacting classifications are performed for the sample (Wu et al. 1...

We study optical and X-ray properties of the ultraluminous IRAS galaxy 10026+4347. This galaxy is a narrow-line QSO with very strong FeII emission. Three optical spectra were taken over two years. The full widths at half maximum (FWHMs) of the emission lines are constant whereas the third spectrum seems to show a continuum change. Intermediate-band...

In the Letter ``An X-Ray Luminous, Dwarf Seyfert Companion of Markarian 273'' by X.-Y. Xia, Th. Boller, H. Wu, Z.-G. Deng, Y. Gao, Z.-L. Zou, S. Mao, and G. Börner (ApJ, 496, L9 [1998]), an observational error occurred that invalidates some of our conclusions. Since Mrk 273x was essentially invisible (B~21) in our acqusition image, in order to posi...

Spectroscopic observations of a sample of 73 very luminous IRAS galaxies (log(L IR/L ⊙) ≥ 11.5 for H 0 = 50 km s -1 Mpc -1, q 0 = 0.5) from the 2 Jy redshift survey catalogue were carried out using the 2.16 m telescope at the Beijing Astronomical Observatory. The observational data, including the optical images (extracted from Digital Sky Survey) a...

Spectroscopic observations of a sample of 73 very luminous IRAS galaxies (log(LIR/Lsun)>=11.5 for H0=50 km\ s(-1) ; Mpc(-1) ,q0=0.5) from the 2 Jy redshift survey catalogue were carried out using the 2.16 m telescope at the Beijing Astronomical Observatory. The observational data, including the optical images (extracted from Digital Sky Survey) and...

Spectroscopic observations of a sample of 73 very luminous IRAS galaxies (log(LIR/L&sun;)>=11.5 for H0=50km/s/Mpc, q0=0.5) from the 2Jy redshift survey catalogue were carried out using the 2.16m telescope at the Beijing Astronomical Observatory. The observational data, including the optical images (extracted from Digital Sky Survey) and spectra for...

We report the discovery of the brightest X-ray source hosted by a faint (MB=-16) dwarf galaxy in the immediate vicinity of the ultraluminous IRAS merging galaxy Markarian 273. The dwarf galaxy, 13 away from Mrk 273, is at the tip of a faint northeast plume of Mrk 273. Its spectrum exhibits strong [O III], Hα, and [N II] emission lines, which establ...

This paper presents the results of spectral observations for the largest complete sample of very luminous IRAS galaxies obtained to date. The sample consists of those 73 objects for which log (L_IR/L_sun) => 11.5 (H0=50 km/s/Mpc, q0=0.5) and mag =< 15.5, and was extracted from the 2 Jy IRAS redshift catalog. All the spectra were obtained using 2.16...

From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored the Seyfert 1 galaxy NGC 7469 continuously in an attempt to measure time delays between the continuum and emission-line fluxes. From the time delays, one can estimate the size of the region dominating the production of the UV emission lines in this source. We find the st...

This paper presents the results of spectral observations for the largest complete sample of very luminous IRAS galaxies obtained to date. The sample consists of those 73 objects for which log(LIR/Lsun)>=11.5 (H0=50 km/s/Mpc, q0=0.5) and mag

The workshop is the second joint workshop aimed mainly at cosmology and the evolution of galaxies between China and Germany. The contributions cover current topics in cosmology and the relevant progressing and planning projects on both sides, as BATC (Beijing - Arizona - Taipei - Connecticut) survey, CADIS (Calar Alto Deep Imaging Survey) projects...

The authors performed a low dispersion spectral observation of a sample of 73 very luminous galaxies, using 2.16 m telescope at XingLong Station of Beijing Astronomical Observatory from Apr 15, 1994 to Feb 15, 1996. They give the results of spectral and interaction classifications of the sample. The statistic results provide strong evidences for th...

We discuss new optical spectra and DSS images of a complete sample of very luminous IRAS galaxies. The statistics of classification of spectral types and interactions show that interaction can account for the nuclear activity (AGN and starburst) of ultraluminous infrared galaxies.

The signature of the self-microlensing in compact binaries (white dwarfs, neutron stars and black holes) is a flare with the characteristic time of typically a few minutes. The probability of detecting these microlensing events can be as high as $1/50$ for a flux sensitivity of $\Delta m=0.01$ in magnitude. The discovery of the self-microlensing by...

This paper combines data from the three preceding papers in order to analyze the multi-wave-band variability and spectral energy distribution of the Seyfert I galaxy NGC 4151 during the 1993 December monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optic...

We present the results of an intensive ground-based spectrophotometric monitoring campaign on the Seyfert galaxy NGC 4151 for a period of over 2 months, with a typical temporal resolution of 1 day. Light curves for four optical continuum bands and the Hα and Hβ emission lines are tabulated. During the monitoring period, the continuum at 6925 A vari...

630 double systems of galaxies brighter than about 17mag(B) were found by examining 100 glass copies of ESO(B) survey plates, covering the Southern Galactic Cap (GLAT

The very luminous infrared source IRAS 23532 coincides with a compact group of galaxies including MCG 04-01-002, MCG 04-01-003 and MCG 04-01-004. Spectroscopic observations show that the bright-nucleus galaxy MCG 04-01-002 is a Seyfert 1 and the disturbed spiral galaxy MCG 04-01-003 is a starburst galaxy. CCD images in V band reveal that clear tida...

On the basis of the data taken from both the Edinburgh/Durham Southern Galaxy Catalogue and the COSMOS-machine-scanned parameter set of the R plate images of the UK Schmidt Telescope Survey field 349, a statistical analysis of the distribution of galaxies with different colours in 4 clusters is presented. It is shown that the fraction of blue galax...

We present the data and initial results from a combined Hubble Space Telescope (HST)/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength m...

In this paper, we present UBVRI photometric results of SN1994D which covers the period from March 11 to April 4. All these data were obtained with a Ford 2048x2048 CCD, which has been attached to the 60/90cm Schmidt telescope in Xinglong station, BAO. The light curves indicate that the supernova is a normal type Ia, a good distance indicator of its...

Astrophysical observations indicate that the ``Local Universe" has a relatively lower matter density ($\Omega_0$) than the predictions of the standard inflation cosmology and the large-scale motions of galaxies which provide a mean mass density to be very close to unity. In such a local underdense region the Hubble expansion may not be representati...

The authors examine a sample consisting of 66 ultraluminous IRAS galaxies with far infrared luminosity. Their images on the glass copies of the Palomar Observatory Sky Survey plates were scanned using the microdensitometer PDS of ESO. The density maps show that the proportion of ultraluminous IRAS galaxies which are interacting or merger system is...

We have examined a sample consisting of 41 ultraluminous IRAS galaxies with far-infrared luminosities $LIR \gt 10^{12}L_\odot\enspace (H_0 = 50 \enspace \text {km s}^{-1}\enspace \text {Mpc}^{-1})$ and a control sample of 41 low-luminosity IRAS galaxies with $LIR\lt 10^{9.7}L_\odot$. All objects are taken from the southern part $(\delta \lt -17_.^\...

Infrared Astronomical Satellite (IRAS) revealed a class of luminous infrared galaxies which emit most (95%) of the energy in the infrared waveband. Much evidence has accumulated showing that they are all disturbed or interacting systems. Sanders et al. (1988) have examined deep CCD images of a complete sample of ten galaxies with far infrared lumin...

Discoveries of the super-large scale structures in the distribution of galaxies (e.g. the giant void in Bootes, the ‘Great Wall’ of galaxies and so-called ‘great attractor’ etc.) have raised the problem of how to determine the characteristic of distributions on very large scale. Two-point correlation function can not meet this requirement. To calcu...

The power law form of the two-point galaxy correlation function ξ, and a relationship between ξ and the three-point correlation function ζ, are derived theoretically. These derivations provide a theoretical basis for expressions that heretofore have been based solely upon observations of galaxy or cluster clustering.

Following our previous paper [1] we here re-examine the correlation between the absorption line density in Lalpha forests N(Zabs) and the emission redshift Zem using a sample of 15 QSOs with medium to high redshifts with Lalpha forests. The present sample covers a greater range in redshift than [1], the emission redshifts ranging between 1.715 and...

Plans to develop a fiber-optic spectroscopy system at the Beijing Astronomical Observatory are given. The system would use a 2.16-m telescope and a planned 1.5/2.2-m Schmidt telescope. A technical description of the spectrograph is given, including the star plate, the fiber bundle system, and the acquiring and guiding bundle. Also, the positioning...

The theoretical form of the four-point galaxy correlation function is, for the first time, derived directly from the BBGKY equations by the method of separating variables. It has the same form as that deduced from observations. The same approach is extended to five- and six-point galaxy correlation functions. A one-to-one correspondence between n-p...

Selection effects on the frequency distribution of quasar redshifts are investigated statistically, with a focus on the correlation between the identification of emission lines and redshift. The distribution predicted by the frequency with which certain key emission lines are used to determine the redshift is compared with the actual redshift distr...

This review paper discusses the methods of identifying redshift systems in quasar absorption spectra and examines current physical models attempting to explain these absorption systems.