The morphological and spectral investigation of the galaxies Kaz 5, Kaz 92, and Kaz 390

The results of morphological and spectral study of the galaxies Kaz 5, Kaz 92, and Kaz 390 are presented. The observations were made on the 2.6-m telescope at the Byurakan Observatory with the VAGR microlenses spectrograph. Isophotes of the images of the galaxies are constructed in the Hα, [NII] λλ6584 , 6548, and [SII] λλ6731, 6717 emission lines and in the continuum. The masses of Kaz 5 and Kaz 92 are determined to be 8.6 × 10⁸ M_⊙ and 6.1 × 10⁹ M_⊙ , respectively. The mass of the gaseous component in the centers of regions I and IV of Kaz 390, which encompass a 1 pixel area, are also determined. The morphological structure of the central region of Kaz 5 in the observed spectral range, λλ6400–6800?, differs completely from the structure of the same part of the galaxy observed with the 6-m and 2.5-m telescopes. It is shown that these differences in the structure in images of Kaz 5 are mostly explained by the comparatively low resolution of the telescope in combination with the VAGR spectrograph. Absorbing matter also contributes to this effect. It is also shown that a “deficit” of nitrogen has been observed in the region of Kaz 390 studied here (a circle of diameter 40″). Translated from Astrofizika, Vol. 52, No. 1, pp. 63–74 (February 2009).     

Data on the spectral variability of Kaz 102

Results from a spectral study of the quasar Kaz 102 are presented. It is shown that its spectrum varies as a whole; that is, the parameters of both the lines and the continuum change. Based on a comparison of results presented previously and in this paper, it is concluded that over a time of approximately 27.5 years the equivalent widths and relative intensities of the lines have increased, while their half widths have decreased. The spectral composition of Kaz 102 has also changed: new lines, HeII λ4686, [OIII] λ4363, and others, appear in spectra of 2000 and 2001 which were not observed in spectra taken in 1973. The electron density, and the mass and effective radius of the gas component are determined to be 2·107 cm-3, 2·10⁴ M_⊙, and 0.2 pc. __________ Translated from Astrofizika, Vol. 50, No. 2, pp. 161–170 (May 2007).     

Velocity field in the galaxy Mark 8 with vigorous starburst centres

The velocity field in the galaxy Mark 8 is studied by means of observations with the 2.6-m telescope at the Byurakan Astrophysical Observatory using the VAGR spectrograph. In the optical range, the central portion of this galaxy consists of five bright condensations which are superassociations (SA). These studies were made in a wavelength range that encompasses images of the galaxy in the Hα and [NII] λλ6548 and 6583Å emission lines. The radial velocity field was obtained. The velocities of all the superassociations were measured and a rotation curve constructed for the galaxy. The relative intensities of the emission lines have been determined. Images are constructed in the Hα and [NII] lines and in the red continuum. It is concluded that the superassociations were formed together and are, as a whole, young. The shape of the rotation curve shows that Mark 8 is an isolated galaxy with a composite multicomponent nucleus. Translated from Astrofizika, Vol. 51, No. 4, pp. 543–553 (November 2008).     

Morphological and spectral study of the galaxies Kaz 69 and Kaz 460

Morphological and spectral studies of the galaxies Kaz 69 and Kaz 460 are reported. The observations were made on the 2.6-m telescope at the Byurakan Observatory using the VAGR multiaperture spectrograph. Isophotes of monochromatic images of the Hα, [NII] λ6584, and [SII] λ6717 lines are constructed. Densifications I and II are found to rotate with north-south oriented axes of rotation. The two densifications (“knots”) have all the kinematic and spectral properties of individual galaxies. It is assumed that Kaz 139 and the densifications I and II were ejected from the nucleus of Kaz 460 at different times, with Kaz 139 probably having been ejected first, although they may all have been ejected simultaneously with different velocities. Along with Kaz 460, these objects form a physical group of galaxies and, at the same time, are a consequence of the activity of the nucleus of Kaz 460. __________ Translated from Astrofizika, Vol. 50, No. 3, pp. 415–426 (August 2007).     

Observation of the [O III] 1 4363 auroral line in the spectrum of kaz 163

The results of spectroscopic observations of the nucleus of the S component of the galaxy Kaz 163, carried out on the 6-m telescope of the Special Astronomical Observatory in 1982, are presented. The equivalent widths, relative intensities, and half-widths of emission lines were determined. The electron temperature, electron density, and mass of the gaseous component of the nucleus were also determined. The half-widths and equivalent widths varied almost twofold over the time of observations from October 31, 1981, to May 28, 1982. During the same time the intensity of the [O III] λ 4363 auroral line increased fairly strongly. Translated from Astrofizika, Vol. 43, No. 2, pp. 183-189, April–June, 2000.     

Spectral observations of galaxies with UV excess

Spectral observations of 19 galaxies with UV-excesses from Kazarian’s list are reported. The spectra were obtained with the 2.6-m telescope at the Byurakan Observatory using the SCORPIO spectral camera. A grism was used to obtain spectra in the wavelength interval λλ7420-3920 Å. 43 spectra in which emission lines are mainly observed were obtained from the 19 galaxies, except for the spectra of Kaz 21, Kaz 178, Kaz 183, and Kaz 184. The spectra of Kaz 17, Kaz 151, Kaz 153, and Kaz 357 have type Sy2 galactic features. In the spectra of the galaxies Kaz 17, Kaz 151, and Kaz 153, absorption lines are observed along with high excitation emission lines such as HeI λ5876 Å and HeII λ4686 Å. No lines were observed within the interval λλ7420-3920 Å in the spectra of the galaxies Kaz 183 and Kaz 184. __________ Translated from Astrofizika, Vol. 49, No. 3, pp. 351–358 (August 2006).     

B and Be-stars in the young open stellar clusters NGC 659 and NGC 7419

The populations of B and Be-stars in the young open clusters NGC 7419 and NGC 659 are studied. Lowresolution spectral observations in the region of the Hα line are used to study 34 members of NGC 7419 and additional spectra in the range λ3700-6200 ? are obtained for 12 stars. During the period of our observations, four previously identified Be-stars manifested an absorption profile for the Hα line. Emission in the Hα line is observed in the spectra of 21 objects. The members of the cluster NGC 7419 are classified as to spectral type. The position of the Be-stars on a two-color IR diagram and a comparison with the position of the objects in other clusters with similar ages cast doubt on the existence of two starformation waves. Moderate resolution spectra were obtained for 22 stars in the cluster NGC 659 over wavelengths of λ4050-5200 ? and for 7 objects in the neighborhood of the Hα line. Emission is observed in both the Hα and Hβ lines for two of the five Be-stars that were studied, while faint emission appears only in the Hα line in one of the stars. The other members of the cluster show no signs of emission in these spectra. T_eff, log g, and Vsini are estimated for the observed stars. It is found that 5 of the objects are not members of the cluster.     

Night-to-night variability of the emission lines in the spectrum of the Seyfert galaxy NGC 3227 nucleus

This is a study of optical emission lines of the nucleus of the Seyfert galaxy NGC 3227. This work is based on 53 spectrograms obtained with the 6-m telescope at the brightness maximum of this galactic nucleus on January 12–15, 1977. A set of profiles of the hydrogen H_α, and H_β lines and the equivalent widths (EW_λ) of six emission lines and blends averaged over series of observations are presented. Broadening of the hydrogen line profiles was observed over the three days. At a level of 0.50 times the peak brightness the hydrogen line profiles were broadened by 12%, 35%, and 44%, respectively. The broadening of the H_β line was accompanied by a reduction in its equivalent width (EW _; ). It is suggested that a flare was observed in the nucleus of the galaxy on a time scale of 3 days, possibly caused to a shock wave in long-lived flows from the galaxy nucleus. __________ Translated from Astrofizika, Vol. 49, No. 4, pp. 499–510 (November 2006).     

The Evolution of Star-Forming Galaxies: The SFR Density of the Universe

The evolution of the Star Formation Rate (SFR) density of the Universe as a function of look-back time is a fundamental parameter in order to understand the formation and evolution of galaxies. The current picture, only outlined in the last years, is that the global SFR density has dropped by about an order of magnitude from a redshift of z∼1.5 to the current value at z=0. Because these SFR density studies are now extended to the whole range in redshift, it becomes mandatory to combine data from different SFR tracers. At low redshifts, optical emission lines are the most widely used. Using Hα as current-SFR tracer, the Universidad Complutense de Madrid (UCM) Survey provided the first estimation of the global SFR density in the Local Universe. The Hα flux in emission is directly related to the number of ionizing photons and, modulo IMF, to the total mass of stars formed. Metallic lines like [OII]λ3727 and [OIII]λ5007 are affected by metallicity and excitation. Beyond redshifts z∼0.4, Hα is not observable in the optical and [OII]λ3727 or UV luminosities have to be used. The UCM galaxy sample has been used to obtain a calibration between [OII]λ3727 luminosity and SFR specially suitable for the different types of star-forming galaxies found by deep spectroscopic surveys in redshifts up to z∼1.5. These calibrations, when applied to recent deep redshift surveys confirm the drop of the SFR density of the Universe since z∼1 previously infered in the UV. However, the fundamental parameter that determines galactic evolution is mass, not luminosity. The mass function for local star-forming galaxies is critical for any future comparison with other galaxy populations of different evolutionary status. Hα velocity-widths for UCM galaxies indicate that besides a small fraction of 10¹⁰-10¹¹ M_⊙ starburst nuclei spirals, the majority have dynamical masses in the ∼10⁹ M_⊙ range. A comparison with published data for faint blue galaxies suggests that star-forming galaxies at z∼1 would have SFR per unit mass and burst strengths similar to those at z=0, but being intrinsically more massive. This revised version was published online in July 2006 with corrections to the Cover Date.     

Morphological and Spectral Study of the Galaxy Kaz 73

Morphological and spectral studies of the nucleus and immediately surrounding regions of the galaxy Kaz 73 are reported. The observations were made on the 2.6 m telescope at the Byurakan Astrophysical Observatory in combination with the multi-pupil VAGR spectrograph. Isophotes are constructed for monochromatic images in the Hα, [NII]λ 6584, and [SII]λ6731 lines. It is shown that the surface brightness of the nucleus in monochromatic images of these lines increases rapidly from the edge to the center, with an increase of 5^m for the Hα line. The nucleus of Kaz 73 is found to rotate clockwise about its axis, which is perpendicular to the direction of the arms of the galaxy. The extent of the nucleus in the direction of the arms is found to be a consequence of its rotation; that is, the nucleus is flattened in the direction of the poles. Overall, the nucleus of Kaz 73 has all the kinematic features of an entire galaxy. The masses of the nucleus and its gaseous component are determined to be 6.5⋅10⁸ M• and 1.9⋅10⁴ M•, respectively.__________Translated from Astrofizika, Vol. 48, No. 2, pp. 291–301 (May 2005).     

Panoramic spectroscopy of galaxies with star-formation regions. a study of SBS 1202?+?583

The methods of panoramic (3D) spectroscopy are used by us in a detailed study of galaxies with ongoing star 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 as being in a continuous phase of star formation. Observations were made with the panoramic spectrographs MPFS at the 6-m telescope of the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences 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 Hα hydrogen recombination line and in the forbidden low-ionization doublets of nitrogen [NII] λλ6548, 6583 and sulfur [SII] λλ6716, 6731, and the ratios of the intensities of the forbidden lines to Hα. The observable characteristics (size, Hα fluxes, etc.) of nine HII regions are studied. The estimated current rates of star formation in the individual HII regions based on the Hα fluxes lie within the range of 0.3-1.2_⨀ M /year. The dependence of the ratio of the intensities of the emission in these above mentioned forbidden doublets on the rate of star formation in the HII regions is found.     

Emission-line CCD imaging of three southern symbiotic stars

Symbiotic stars that are strong radio sources and have cool dust emitting in the infrared are expected to have extended emission nebulae around them. In order to search for such emission nebulae, we have carried out CCD imaging of three symbiotic stars (R Aqr, RR Tel and H1-36) with narrow-band filters centred at the emission lines of [O III] λ5007, Hα λ6563, [N II] λ6584, [S II] λ6717 + 6731. RR Tel and H1-36 images do not show any extended nebulosities around them. The CCD image of the R Aqr nebulosity in the high excitation [O m] line is different from its image in Hα and the low excitation lines of [N II] and [S II] indicating ionization-stratification in the nebula. In H1-36 the optical nebulosity (if it exists) is smaller than ∽2 arcsec while the radio image size is known to be large (∽5 arcsec). This behaviour is opposite to that seen in R Aqr in which the radio emission comes from the core region of a much larger optical nebulosity. Interstellar and/or circumstellar extinctions are suggested to be responsible for this difference     

Spectrophotometric Study of Galaxies with UV Excess

Results from a spectrophotometric study of 21 galaxies with UV excess are presented. The half widths (FWHM) and equivalent widths of observed spectrum lines of these galaxies, as well as the relative intensities of the emission lines observed in the spectrum of the galaxy Kaz243, are determined. It is conjectured that the latter galaxy has the properties of an Sy2 type galaxy. The electron densities and masses of the gaseous components are found for 15 galaxies, along with the masses of 8 galaxies for which the ratio M/L has been calculated. It is shown that the spectral structures of these galaxies do not depend on whether they are members of physical systems or are isolated.     

Spectral study of the flare star EV Lac

Spectral observations of the flare star EV Lac made on the 2.6-m telescope at the Byurakan Observatory in 2000–2002 are reported. A powerful flare was detected and it was possible to follow the variation in the equivalent widths of the Hα and Hβ lines, both during the flare and during the quiescent phase of the star. It is shown that the profiles and equivalent widths of the lines underwent substantial changes. The equivalent widths of these emission lines reached a maximum roughly 40 min after the flare maximum. __________ Translated from Astrofizika, Vol. 49, No. 4, pp. 573–583 (November 2006).     

New Spectrophotometric Data on the Nuclei of the Galaxies Kaz 26 and Kaz 73

The results of a spectroscopic study of the nuclei of the galaxies Kaz 26 and Kaz 73 are presented. The relative intensities of emission lines and the equivalent widths, halfwidths, and expansion velocities of lines at the continuum level are calculated. The electron densities and the masses of the gaseous components of their nuclei are determined. The numbers of stars generating the emission from the gaseous components and nuclei of the galaxies are also determined. The degree of ionization of the gas in each galactic nucleus is calculated. It is concluded that the nucleus of Kaz 26 resembles that of a "starburst" galaxy in its physical properties. It is shown that Kaz 73 is a liner (Sy 3).     

Spectral observations of the novalike star TT Ari. II

Results from a spectral study of one of the brightest cataclysmic variables, the star TT Ari, are presented. They are generally in good agreement with previous observations, but there are some differences. The luminosity of the star, as well as the equivalent widths of emission lines, reveal variations that are probably periodic in character. Emission from the star in the CIV 5801Å and 5812 Å lines is observed for the first time. The observed variations in the symmetry of the broad absorption Balmer series (beginning with Hβ) may be a consequence of the appearance of a P Cyg line profile. The Hα line manifests a P Cyg profile consisting of two components corresponding to 600 and 1900 km/s. The average of the ratio EWHα/EWHβ indicates that the formation of these lines may be explained, at least partially, in terms of a simple photoionization-recombination model. __________ Translated from Astrofizika, Vol. 51, No. 3, pp. 445–460 (August 2008).     

Study of the HII regions in the spiral galaxy NGC6384

The galaxy NGC6384 has been observed with an IPCS through Hα and [NII] narrow-band interference filters for direct imagery with the 2.6-m Byurakan telescope. We studied the main physical parameters of the identified 98 HII regions, their diameter and luminosity functions, as well the [NII]/Hα ratio distribution. The integrated distribution function of the HII region diameters can be well fitted by the exponential function. The characteristic diameter has the value (Do = 217 pc) predicted for a galaxy of its measured luminosity. The luminosity function of HII regions has a double power law profile with relatively shallow slope at low luminosities (α = −0.4), an abrupt turnover at logL(Hα) ≈ 38.75, and sharper slope at higher luminosities (α = −2.3). The correlation between the luminosity and diameter of HII regions confirms that in general they are constant density, radiation-bound systems. [NII]/Hα ratio data for the HII regions show that there is a negative radial gradient of [NII]/Hα. In the central region of the galaxy, nitrogen abundance is higher than in the periphery. The properties of the HII region population of this AGN galaxy do not differ significantly from the properties of the HII region population of the “normal” galaxies. Reexamining the location of the type Ia SN 1971L in the galaxy, we confirm that it lies on the spiral arm at about 8″.6 far from the closest HII region N 53 (F81). Such a location can be taken as proof that the progenitor of this SN does not belong to an old, evolved stellar population. Published in Astrofizika, Vol. 50, No. 4, pp. 519–533 (November 2007).     

Ionized gas characteristics in the cavities of the gas and dust disc of the spiral galaxy NGC 6946

The parameters of the ionized gas in NGC 6946 (in the [NII] λλ6548, 6583, H _α and [SII] λλ6717, 6731 lines) are investigated with the SAO RAS BTA telescope along three positions of the long slit of the SCORPIO focal reducer, passing through a number of large and small cavities of the gaseous disc of the galaxy. These cavities correspond exactly to the cavities in warm dust, visible at 5 − 8μm. We found that everywhere in the direction of NGC 6946 the lines of ionized gas are decomposed into two Gaussians, one of which shows almost constant [SII]/H _α and [NII]/H _α ratios, as well as an almost constant radial velocity within the measurement errors (about −35… − 50 km/s). This component is in fact the foreground radiation from the diffuse ionized gas of our Galaxy, which is not surprising, given the low (12°) latitude of NGC 6946; a similar component is also present in the emission of neutral hydrogen. The analysis of the component of ionized gas, occurring inNGC 6946, has revealed that it shows signs of shock excitation in the cavities of the gaseous disc of the galaxy. This shock excitation is as well typical for the extraplanar diffuse ionized gas (EDIG), observed in a number of spiral galaxies at their high Z-coordinates. This can most likely be explained by low density of the gas in the NGC 6946 disc (with the usual photoionization) inside the cavities, due to what we see the spectral features of the EDIG gas of NGC 6946, projected onto them, and located outside the plane of the galaxy. In the absence of separation of ionized gas into two components by radial velocities, there is an increasing contribution to the integral line parameters by the EDIG of our Galaxy when the gas density in NGC 6946 decreases, which explains some strange results, obtained in the previous studies. Themorphology of warmdust, visible in the infrared range and HI is almost the same (except for the peripheral parts of the galaxy, where there are no sources of dust heating).Moreover, the shock excitation of the ionized gas is detected in the smallest holes, distinguishable only in the IR images.     

Wind and Disk Diagnostics in PMS Stars. A Critical Analysis

The relationships among traditional wind and disk diagnostics - Hα and [OI]λ6300 lines and IR luminosity excesses, respectively - and star parameters are critically analysed. The total sample includes 109 PMS stars - 20 Weak-line T Tauri (WTTS), 45 Classical T Tauri (CTTS) and 44 HAeBe stars-. Our results suggest that Hα is neither a wind nor an accretion tracer. Hα and [OI] emissions seem to correlate very well with the photospheric luminosity and not with ΔL_IR/L_ph, a parameter related to the origin of the IR excesses. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectroscopic evolution of nova LW serpentis 1978 during its early decline

Optical spectroscopic data are presented on nova LW Serpentis 1978, obtained during its decline fromV 9.0 to ≃10.2 (compared to a value of ∼ 8.0 at recorded maximum). The spectrum and its evolution compare well with a typical nova, though the principal absorption (∼ −750 km s^−l) was very weak in comparison with the diffuse-enhanced absorption (∼ −1300 km s⁻¹). The principal absorption could be identified only in the lines of O I λλ7774, 8446, and in moderate-resolution observations of Hα. The salient features of spectral evolution follow: The near-infrared triplet of Ca n continuously weakened. O I λ8446 was always brighter than O I λ 7774, indicating continued importance of Lyman Β fluorescence. The lines due to [O I], [N II] and N n brightened considerably near the end of our observations (37 days from maximum). The Hα emission line was asymmetric all through with more emission towards the red. Its emission profile showed considerable structure. Based on the individual peaks in the Hα line profile, a kinematical model is proposed for the shell of LW Ser. The model consists of an equatorial ring, and a polar cone on the side away from the earth. The nearer polar cone did not show significant emission of Hα during our observations. The polar axis of the shell is inclined at a small angle (∼ 15‡) to the line of sight.