Panoramic Spectroscopy of Galaxies with Star-formation Regions. A Study of SBS 1202+583
S. A. Hakopian, S. K. Balayan, S. N. Dodonov, A. V. Moiseev, A. A. Smirnova
11 PANORAMIC SPECTROSCOPY OF GALAXIES WITH STAR-FORMATIONREGIONS. A STUDY OF SBS 1202+583
S. A. Hakopian, S. K. Balayan, S. N. Dodonov, A. V. Moiseev, and A. A. Smirnova The methods of panoramic (3D) spectroscopy are used by us in a detailed study of galaxies with ongoingstar formation chosen from among objects in seven selected fields of the Second Byurakan Survey (SBS).This article deals with the irregular galaxy SBS 1202+583, which our classification scheme identifies asbeing in a continuous phase of star formation. Observations were made with the panoramic spectrographsMPFS at the 6-m telescope of the Special Astrophysical Observatory (SAO) of the Russian Academy ofSciences and VAGR at the 2.6-m telescope of the Byurakan Astrophysical Observatory (BAO) in Armenia.The data are used to construct maps of the radiative fluxes in the continuum and various emission lines.Special attention is devoted to analyzing the emission in the H α hydrogen recombination line and in theforbidden low-ionization doublets of nitrogen [NII] λλ λλ α . The observable characteristics (size, H α fluxes,etc.) of nine HII regions are studied. The estimated current rates of star formation in the individual HIIregions based on the H α fluxes lie within the range of 0.3-1.2 (cid:1) M /year. The dependence of the ratio ofthe intensities of the emission in these above mentioned forbidden doublets on the rate of star formationin the HII regions is found. Keywords:
1. Introduction
The Second Byurakan Survey (SBS) [1], which was carried out using the 1-m Schmidt telescope with anobjective prism, has been one of the most productive of the low-dispersion surveys for discovering active galaxies.
Astrophysics, Vol. 55, No. 1, March , 2012 © (1) V. A. Ambartsumyan Byurakan Astrophysical Observatory, Armenia; e-mail: [email protected](2) Special Astrophysical Observatory, Russia α Abstract.
The SBS has a special role in the detection of galaxies with not only distinct signs of star formation activity, suchas blue dwarf galaxies (BCG, or blue compact galaxies), as known, but also for finding galaxies with less distinctsigns of star formation [2]. This is conditioned, in particular, by the aim to avoid missing the objects being soughtwhile working with the low-dispersion spectra. Thus, the lists included not only objects with obvious indications ofcorrespondence to the selection criteria, but also those with dubious indications. This applied most often to objectswith visible magnitudes close to the sample limit. 18 m .5-19 m .5. So it is possible to analyze or work with samples inindividual fields of the SBS only after “cleaning up” the original lists by means of follow-up spectroscopy of higherresolution.We have made slit spectroscopic observations of ~500 objects from the SBS which form the base sample[3 and references therein]. This included galaxies with extended morphologies that were chosen as active from sevenselected fields of the SBS [4]. The objects were classified according to our scheme for spectral classification [5], asadapted to the available data and standard classification criteria. This yielded 345 galaxies (more than 70% of thesample) with confirmed signs of star formation activity. Most of the remainder manifested signs of being activegalactic nuclei (AGN).Galaxies with star formation activity are denoted by SfG (Star forming Galaxies) in our classification scheme[5]. For simplicity, the sample is divided into two subclasses, depending on the equivalent width of the H α emissionline (by analogy with Ref. 6), which are SfGcont (cont = continual) for ( ) <α Å, and SfGneb (neb = nebular)for ( ) >α Å, which includes the objects with greater current star formation: blue compact galaxies, HIIgalaxies, etc. Further development of this scheme is one of our priorities. In fact, as opposed to galaxies with nuclearactivity, for which a fairly precise classification scheme exists, various authors use different terminology for galaxieswith star-formation activity, which can lead to substantial errors, especially in statistical studies employing publisheddata from different sources.At this point we are making detailed studies of individual galaxies from the SfG sample beginning with theobjects that are the most complicated from the standpoint of morphology. These studies are based on panoramic (3D)spectroscopy with the MPFS spectrograph on the 6-m telescope at the Special Astrophysical Observatory (SAO) ofthe Russian Academy of Sciences and the VAGR spectrograph on the 2.6-m telescope at the Byurakan AstrophysicalObservatory (BAO). These data can be used for simultaneous examination of both the spectral and morphologicalfeatures of the objects and contain much useful information on spectrophotometric properties of galaxies. Besidesobtaining unique material on individual objects, we plan, as data are accumulated, to gain a more profoundunderstanding of the nature of star-formation activity in the overall chain of evolutionary processes taking place inthe universe.This article is the second in a series of planned publications on this topic. The first was devoted toSBS1533+574, a two-component galaxy in the nebular phase of star formation [7]. The galaxy SBS1202+583, whichis the subject of this article, is in the continuous phase of star formation and has an irregular structure.This article consists of seven parts, including the
Introduction and
Conclusion . Data from the Sloan DigitalSky Survey (SDSS), release DR7 [8], are presented in part 2 and serve as a kind of morphological guide for thesubsequent analysis. The third and fourth parts mostly contain information on the making of the observations. Part5 contains the results of an analysis of the maps of the H α emission intensity. The existence of nine HII regionsis demonstrated and their characteristics are reported. Data on emission in the forbidden low-ionization doublets ofnitrogen [NII] λλ λλ
2. Morphological features of SBS 1202+583 according to the SDSS
The galaxy SBS 1202+583 (alternatively, UGC 07070 NED02, VV270ab, etc.) was included in the SBScatalog as a binary object, based on the appearance of only emission lines, i.e., without any signs of an ultravioletexcess. Its major characteristics according to data from NED [9] and LEDA [10], i.e., its diameter, visible and absoluteB magnitudes, distance calculated with a Hubble constant H = 73 km/s/Mpc, and projected scale, are 1'.1 × m .53,-17 m .93, 37.2 Mpc, 180 pc/arcsec, respectively.In the optical images, this galaxy has an irregular structure consisting of individual condensations, which canbe seen, especially, in the SDSS DR7 images (Fig. 1a ). This largest of the seven comparatively bright condensationsis nominally at the center and is denoted by “C” in the figure. The others are designated by the quadrant relative In the images shown in this article, as in Fig. 1a, north is upward and east is to the left.
Fig. 1. From the SDSS archive: (a) thesum over five filters of an image of SBS1202+583 with our notation for theSDSS components and the two last digitswhich differentiate their identificationnumbers. The entire number for C is587731891652198444. (b) The spect-rum of the central condensation C and afragment of an SDSS image with thecentral component C on a differentintensity scale. (cid:2) to C in which they lie. All seven are photometric SDSS objects identified by coordinates which correspond to thecenters of the circles indicated in Fig. 1a. In this paper they show up as SDSS components. In the SDSS photometriccatalogue, component C corresponds to the identification number 587731891652198444, while the identificationnumbers of the other condensations vary only in the last two digits, which are indicated in Fig. 1a.
3. Panoramic spectroscopy: observations and data processing
SBS 1202+583 was observed using the MPFS (Multipupil Fiber Spectrograph) [11] at the primary focus ofthe 6-m telescope at the SAO and the VAGR [12] at the primary focus of the 2.6-m telescope at the BAO. The objectwas observed twice with the MPFS, with different CCD arrays and diffraction gratings, and twice with the VAGR usingbroad-band interference filters for different spectral ranges. Information on the observations is listed in Table 1. Thecenters of four fields are shifted relative to one another, but all four contain the SDSS component C. Confirmationof the presence of the SDSS components indicated in Fig. 1a in each of the fields is provided by Fig. 2.For initial processing of the MPFS observations, involving a standard set of procedures, which includewavelength and flux calibrations, and, partially, for visualization and analysis of the data, there were used programs[e.g. 13 ] written in Interactive Data Language (IDL). The ADHOCw program package [14] was used for visualizing,analyzing, and illustrating the data obtained with both spectrographs. It also was used for primary processing of thedata from the VAGR spectrograph. Here the data were not calibrated in terms of flux because there were noobservations of a spectrophotometric standard. The parameters of the lines were determined using a gaussianapproximation for the spectral profiles. Fig. 1. Continued. (cid:3) (cid:4)(cid:3)(cid:3)(cid:3)
Wavelength, Å F λ [ - e r g / c m / s / Å ] z = 0.087 ± 0.0000 (0.95) (cid:5)(cid:3)(cid:3)(cid:3) (cid:6)(cid:3)(cid:3)(cid:3) (cid:7)(cid:3)(cid:3)(cid:3) (cid:8)(cid:3)(cid:3)(cid:3) (cid:9)(cid:3)(cid:3)(cid:3)(cid:10)(cid:3)(cid:11)(cid:3)(cid:12)(cid:3)(cid:4)(cid:3) (cid:13) γ (cid:1) β (cid:1) (cid:14)(cid:15)(cid:16)(cid:16)(cid:16)(cid:17) (cid:14) (cid:18) (cid:19)(cid:16)(cid:16)(cid:17)(cid:14)(cid:15)(cid:16)(cid:17) (cid:14)(cid:20)(cid:16)(cid:16)(cid:17) α (cid:1) RA = 181.24608DEC = 58.10724
4. Results of observations with the VAGR spectrograph in 2005
All seven of the SDSS components (Fig. 2) show up only the field observed with the VAGR spectrograph in2005. Only the forbidden oxygen [OIII] λλ Here and in the following, the intensity peak is taken to be the element of the array at which the highest intensity is reached.
TABLE 1. Details on the Observations of SBS 1202+583Fig. 2. The sum over five filters ofan SDSS image of SBS 1202+583,together with the entire field for ourobservations with MPFS (indicatedby the inner rectangles) and theinformative part of the field for theobservations with VAGR (outerrectangle and part of a circle).
Telescope (observatory) ZTA 2.6-m (BAO) BTA 6-m (SAO)Spectrograph VAGR MPFSCCD array Lick Tektronix EEV 40-42number of pixels 2063 × × × ≈ D ×
16 16 × lines, i.e., the nebular N1 line and, along the very edge of the range, N2. Figures 3, a, b, and c show maps of theemission derived from the VAGR 2005 data over the entire range of the filter, in a small segment of the continuum,and in the nebular N1 line, respectively. In these figures, the same segment of the sky is isolated as in Fig. 1a, withwhich Fig. 3a is easily identified. The continuum intensity distribution of Fig. 3b has a single peak. It lies withinthe confines of the central component and the array element corresponding to it in Figs. 3, b and c, is indicated bythe letter “c.”The faintest of the SDSS components, SE1 does not stand out in the field. The north-east components NE4and NE2 of Fig. 3c are the most intense emitters in the nebular doublet lines. Here the highest intensity in the field,which is detected in the peak of component NE4 and is indicated by a cross in Fig. 3c, is almost twice as intenseas the emission in the peak from component NE2. In both components the maximum is reached after a smooth risein intensity from the edge to the center, so that randomness in the position of the peaks can be excluded.
5. Recombination line emission. HII regions
The star-formation activity of galaxies originates in their star-formation regions, which are associated primarilywith regions of ionized hydrogen, i.e., HII regions. The most distinctive spectral feature of HII regions in the visiblerange is their emission in the hydrogen Balmer H α line.The H α emission of this galaxy shows up in the three recorded spectral regions for the MPFS 2007, MPFS2002, and VAGR 2004 observations (Table 1). The two-dimensional distributions of the H α emission intensityderived from these data are shown as a background in Figs. 4a, 4b, and 5, respectively. With the help of the threepartially overlapping fields nine regions of ionized hydrogen were revealed; hence the object under study can becharacterized as a complex of HII regions. Six of the nine HII regions are identified with SDSS components.We use the designations NE5, NE6, and NE7 for the three HII regions that are not associated with SDSScomponents; they lie to the north east of the central component C. All three are clearly visible in the H α intensityFig. 3. Distributions of emission intensity obtained with the VAGR spectrograph in2005: (a) total over the entire spectral range of the filter; (b) total over the continuumsegment 5080-5110 Å, for which the peak corresponds to pixel “c” of the array; and, (c)in the [OIII] λ × a b c maps obtained with the MPFS (Figs. 4, a and b). They were also resolved in the VAGR 2004 field, although theylie on the very edge (Fig. 5b). NE7 has the smallest size of all the nine objects. NE5 shows up distinctly in theVAGR 2004 field and in the SDSS images, and is indicated by an arrow in Fig. 1a. It stands out for its smalldimensions and circular outlines, and, especially, for the fact that it is observed in all of our fields; this makes itconvenient for matching when comparing the data.As all three H α intensity maps show, two HII regions can be observed within the central SDSS componentC. The smooth drop in the intensity from the two local peaks observed in C is best illustrated (cf. Fig. 4b) by thewhite contours in the field of MPFS 2002, where C lies at the center. The binary structure of C also shows up inthe SDSS images (see the corresponding fragment in Fig. 1b). We denote the western, larger HII region by C1 andthe other, by C2. The continuum emission map derived from the MPFS 2002 data (Fig. 4c) confirms (see part 4, Fig.3b) the existence of a single peak in this distribution and shows more clearly that it lies in C1 and is coincidentwith the Ha emission peak of C1.The HII regions associated with the SDSS components NE4 and NE2 emit more brightly than the others inH α ; these have already recommended themselves as the brightest regions for emission in the nebular N1 line(part 4, Fig. 3c).Of the recombination lines (besides H α ), only in the spectra of NE4 and NE2 is the singly ionized heliumHeII λ α ; at thepeak for NE4 it equals I (He) maxNE4 = × -17 erg/cm s and it is half this for NE2. The intensity of the H α emissionis given in Table 2.The MPFS 2007 data, have higher spectral resolution the VAGR data, and in the field of which more HIIregions are observed than in the MPFS 2002 and VAGR 2004 data, provide us with homogeneous data on all theseven HII regions mentioned above. These include the largest and brightest of all the HII regions that we haveFig. 4. Flux maps derived from MPFS data: (a) data from 2007; (b, c) data from 2002. Thecontours in (a), (b), and (c) are drawn in accordance with the H α emission. The backgroundin (a) and (b) shows the distribution of the radiation in the H α line, and in (c), the distributionwithin a continuum segment 6700-6715 Å of the spectrum. (cid:2) (cid:13) (cid:21) Here and in the following, if not otherwise specified, the contours reflect an incomplete range of intensities, and the backgroundshading, a complete range; here the darker shades correspond to a higher intensity. observed. Thus, the range of variation of some of the parameters can be used to characterize the entire set of dataas a whole. It should be noted that lower bound estimates are given for regions C1 and C2, since roughly 20-30%of their area is cut off by the field of MPFS 2007, as a comparison with the MPFS 2002 field shows.The parameter values in the first five rows of Table 2 obtained from data from MPFS 2007 for the seven HIIregions are related to the H α emission. In order, these are the peak H α emission ( ) max I α H , the heliocentric radialvelocity ( ) maxr V α H determined from the H α line in the same array element, the equivalent radius of the HII regionestimated using the formula ( ) .eq SR π= , the integrated radiation flux F (H α ), and the star formation rate ( ) α HSFR calculated from the H α luminosity using the formula ( ) α HSFR second term in second parentheses:TABLE 2. Comparative and Absolute Characteristics of the HII Regions According tothe MPFS 2007 Data
NE4 NE2 C1 C2 NE5 NE6 NE7 − α maxI (erg/cm s) 23.34 11.33 3.61 2.81 4.56 2.53 2.69 maxrV )(H α (km/s) 2556 2554 2529 2544 2548 2554 2555 R eq (pc) 460 325 166 145 237 168 84 α F (erg/s) 14.8 9.36 5.06 4.56 5.65 4.33 4.67 )SFR(H α ( /year (cid:2) M ) 1.17 0.74 0.40 0.36 0.45 0.34 0.37 − λ maxI (erg/cm s) 0.99 0.34 0.51 0.68 0.35 0.45 0.26 − λ maxI (erg/cm s) 1.45 0.64 0.62 0.53 0.34 0.40 0.18 − λ maxI (erg/cm s) 0.75 0.46 - - - - - Fig. 5. Distribution of H α radiation, background, and contoursderived from the VAGR 2004 data covering the entire field in (a),and the north eastern part of the field (magnified) in (b). (cid:2) (cid:13) ( ) ( ) α×= − H 1097year L.M (cid:2) [15]. The area S of the radiating surface was determined from the number of arrayelements in which the intensity exceeds a threshold value ( ) thresh I α H , which, in turn, was determined separately foreach HII region, generally using the formula ( ) ( ) maxthresh I.I α×=α
H10H .The table shows, in particular, that the star formation rate of the individual HII regions ranges from a minimumof 0.34 year (cid:1) M for NE6 to a maximum of 1.2 year (cid:1) M for NE4. The ranges of the other parameters,except V r , are given by the values for the HII regions NE7 and NE4.The two HII regions that were not in the field of MPFS 2007 are characterized by intermediate values of theparameters. One of them is associated with the SDSS component SE1 (Fig. 4b) and the other, with SW1(Fig. 5). Both lie to the south of the central component and, while in projection against the celestial sphere, theyare its nearest neighbors, the two appear to be more isolated compared to the other HII regions.In terms of its parameters SE1 is comparable to NE5. This applies to its shape as well as to the peak intensityand the equivalent radius, which are roughly 1.2 times the values for NE5 according to the data from MPFS 2002.The HII region SW1 appears in the central part of the VAGR 2004 field (Fig. 5a). The peak of the continuumemission coincides with the local peak of the H α emission for C1; it is indicated by “c.” The H α intensity in thepeak of SW1 is roughly the same as in the peak of C1, greater by a factor of 1.2, and is greater by a factor of 1.7than in the peak of NE5. It should be noted that here, closer to the edges of the field where C and NE5 lie, the errorsare greater than in the center of the field (where SW1 lies).
6. Forbidden line emission of the HII regions according to the MPFS 2007 data
Within the spectral range observed by MPFS 2007 (Table 2), the doublet lines of singly ionized nitrogen [NII] λλ λλ λ F λ [ - e r g / c m / s / Å ] (cid:6)(cid:12)(cid:3)(cid:3)(cid:3) (cid:14)(cid:15)(cid:16)(cid:17) α (cid:1) (cid:6)(cid:4)(cid:3)(cid:3) (cid:6)(cid:6)(cid:3)(cid:3) (cid:6)(cid:8)(cid:3)(cid:3) (cid:7)(cid:11)(cid:3)(cid:3) (cid:6) (cid:12) (cid:3)(cid:3) (cid:10)(cid:11)(cid:12)(cid:4) (cid:6)(cid:5) (cid:4) (cid:8) (cid:6)(cid:5) (cid:8)(cid:12) (cid:6)(cid:6) (cid:7) (cid:8) (cid:6) (cid:7) (cid:10) (cid:7) (cid:7) (cid:10) (cid:12) (cid:6)(cid:6) (cid:7) (cid:12) (cid:10) (cid:14)(cid:19)(cid:18)(cid:18)(cid:16)(cid:16)(cid:17) (cid:14)(cid:20)(cid:16)(cid:16)(cid:17) (cid:14)(cid:22)(cid:23)(cid:16)(cid:16)(cid:16)(cid:17)(cid:24)(cid:25)(cid:16) λ σ noise level of the continuum. Thepicture is roughly the same for the neutral oxygen [OI] λ .z ≈ , it partially overlaps the [OI] λ λ λ line and in the sum of the sulfur [SII] λλ ,6731 doublet lines are shown, respectively, in Figs. 7a and 7b by white contours. A comparison of these distributionswith the distribution of H α , which is shown in both figures by dark contours, reveals some differences that are mostobvious within NE4. The intensities of the emission at the peaks of the seven HII regions in the three forbiddenlines [ ] ( ) max I λ , [ ] ( ) max I λ , and [ ] ( ) max I λ are listed in the bottom rows of Table 2.The ratios of the intensities of the forbidden lines to the permitted lines (denoted by fp R below) arecustomarily used as a criterion for determining the type of activity in galaxies [e.g. 16 and the references therein].The ratios fp R play a basic role in our classification scheme [5], which was developed for uniform processing ofspectral data, especially for the purpose of distinguishing galaxies with nuclear (AGN) or star formation (SfG) activity,even when these indicators are faint. In studying SfG galaxies we are, in particular, interested in a range of valuesof fp R that is determined primarily by the chemical composition of individual HII regions.The galaxy SBS λ α emission intensities and the light contours, tothe emission intensities in (a) the [NII] λ λ λ λ α in (a) and [SII]( λ λ α in (b). a b λ λλ α line, which are denoted by [ ] αλ= H6583NII R and [ ] ( ) αλ+λ= H67316716SII R . The distributions of R and R over the field of MPFS 2007 are shown in gray-scale in Figs. 7a and 7b; there the scale indicates their range of variation and the numbers given on the figures wereobtained by averaging over each of the HII regions. These same values are listed in Table 3, right after the similarlyaveraged values of the H α emission intensity.The average values of R for the HII regions lie nonuniformly between 0.05 and 0.16 and are grouped bytwo each at the beginning and end of this interval, and by three near 0.1, which can be regarded as the maximumof the distribution of R . The maximum of the distribution of the averages of R for the HII regions lies at 0.19.The width of the interval which they encompass is 0.11-0.23, despite the fact that this, the ratio of the sum of thetwo lines to H α , is almost the same as for R .We were unable to find a direct dependence of the average values of R and R for the HII regions on thestar formation rate SFR. However, there appears to be a dependence of the ratio of these quantities, RR , on SFR(Fig. 8) or, equivalently, of the ratio of the averages over the HII regions of the intensities of the [NII] λ lineand the sum of the [SII] λλ , 6731 lines. Further studies will show whether this dependence extends to HII regionsin other galaxies and can be used as a diagnostic for preliminary estimation of the star formation rates.The dependence that was obtained is interpreted as a decreasing in ( ) ( ) λ+λλ II withincreasing rates of star formation SFR of the individual HII regions. It can be said with high probability that for starformation rates (cid:1) M < the emission in the [NII] λ λ λλ α ) in units of( /year (cid:1) M ) on the ordinate. ( ) ( ) λ+λλ SF R (cid:10)(cid:26)(cid:3)(cid:3)(cid:3)(cid:26)(cid:3)(cid:3) (cid:3)(cid:26)(cid:8)(cid:3) (cid:3)(cid:26)(cid:6)(cid:3) (cid:3)(cid:26)(cid:4)(cid:3) (cid:3)(cid:26)(cid:11)(cid:3)(cid:3)(cid:26)(cid:4)(cid:3)(cid:3)(cid:26)(cid:8)(cid:3)(cid:10)(cid:26)(cid:11)(cid:3)(cid:3)(cid:26)(cid:11)(cid:3)(cid:3)(cid:26)(cid:6)(cid:3)(cid:10)(cid:26)(cid:3)(cid:3)(cid:10)(cid:26)(cid:4)(cid:3) (cid:19)(cid:27)(cid:6) (cid:19)(cid:27)(cid:7)(cid:28)(cid:10) (cid:19)(cid:27)(cid:5) (cid:28)(cid:11)(cid:19)(cid:27)(cid:11) (cid:19)(cid:27)(cid:4) λλ λλ , 6731 forbidden line is detected only from the HII regionsNE4 and NE2 that lie in the upper part of the curve in Fig. 8.As for the intensity ratio of the lines in the sulfur doublet, ( ) ( ) λλ= IIn e , which in the case ofphotoionization is an indicator of the electron density, if it exceeds 80-100 cm -3 , then for most of the HII regionsit has an average value of 1.2. NE7 is characterized by a slightly lower value, 0.9. NE4 and NE2 are different, withslightly larger values of n e . The average for NE2 is roughly 1.5, and within NE4, it increases from 1.2 at the centerto 1.6 at the edge.
7. Conclusion
We have presented 3D spectroscopy data for SBS 1202+583 from the 6-m telescope at the SAO of the RussianAcademy of Sciences and the 2.6-m telescope at the BAO of the Academy of Sciences of the Armenian Republic thathas been acquired as part of a comprehensive study of selected galaxies from the SBS sample. The panoramic MPFSand VAGR spectrographs have been used to obtain data in four overlapping fields, which made it possible, inparticular, to analyze the distribution of the emission from SBS 1202+583 in the most intense recombination andforbidden lines in the 490-520 and 600-780 nm ranges. The distribution of the H α emission reveals the existenceof nine HII regions, each of which has been studied individually. Six of them are associated with SDSS photometricobjects. The distribution of the continuum radiation indicates the existence of a single intensity peak, so that theobject under study can be characterized as a unified complex of HII regions.The presence of seven of the HII objects, including the brightest and largest, in one of the fields, MPFS 2007,ensures uniformity of the data, so that it is possible to estimate the ranges of variation of several characteristics ofthe HII regions in this study. In particular, the equivalent radii of the HII regions ( R eq ) lie within a range of 84-460pc, and the rates of star formation (SFR) calculated from the H α luminosity lie within year1.2-0.3 (cid:1) M . An analysisof the ionized gas forbidden lines reveals a dependence of the ratio of the intensities in the [NII] λ λλ NE4 NE2 C1 C2 NE5 NE6 NE7 avg − α I (erg/cm s) 85.3 54.0 29.8 26.4 32.8 25.0 26.9 avg R avg R I avg (6583)/ I avg (6716+6731) 0.26 0.55 0.70 0.58 0.64 0.94 0.71 REFERENCES
1. B. E. Markarian and J. A. Stepanian,
Astrofizika , 354 (1983).2. S. A. Hakopian, Candidate’s dissertation, Erevan (2002).3. S. A. Hakopian and S. K. Balayan,
Astrofizika , 267 (2002).4. S. A. Hakopian and S. K. Balayan, in: Y. Terzian, E. Khachikian and D. Weedman, eds., Proceedings of IAUSyposium 194: Active Galactic Nuclei and Related Phenomena, Aug. 17-21, 1998, Yerevan, Armenia, AstronomicalSociety of the Pacific , San Francisco (1999), p. 162.5. S. A. Hakopian and S. K. Balayan,
Astrofizika , 354 (2004).6. R. Terlevich, Rev. Mex. Astron. Astrofis. Ser. Conf . , 1 (1997).7. S. A. Hakopian, S. K. Balayan, S. N. Dodonov, and A. V. Moiseev, Astrofizika Baltic Astronomy , 518 (2000).13. A. A. Smirnova, A. V. Moiseev, and V. L. Afanas’ev, Pis’ma v Astron. zh . Astrophys. J . , 22 (1994).16. S. Veilleux and D. E. Osterbrock, Astrophys. J. Suppl. Ser. , 295 (1987)., 295 (1987).