Characteristics of Star-forming Regions in the Advanced Minor-merger, Luminous Infrared Galaxy NGC 4194
We report the results of long-slit spectroscopy at position angles68°, 131°, and 164° for the minor-merger NGC 4194, aluminous infrared starburst galaxy. The mass within 1.2 kpc of thedynamical center is estimated to be 4.8 × 109 to 1.7× 1010 M &sun;, depending on the assumedinclination to the plane of the sky. The star formation rate (SFR) inthe areas sampled is 8 M &sun; yr-1. Themetallicity, log(O/H) + 12, ranges from ~8.8 to >9.0 in regions ofsignificant star formation, suggesting that the metallicity has beenenhanced by the current star formation. The star-forming regions rangein age from 5 to 9 Myr, with the youngest ages occurring in the regionsof high SFR. Electron temperatures and the location of the spectra inemission line diagnostic diagrams suggest the presence of shock waves,presumably due to the presence of supernovae, winds from massive stars,and/or collisions of clouds due to the merger. The presence of massivestars and supernovae is consistent with the ages determined for thestar-forming regions. The ages of the continua produced by the stellarpopulation are estimated to range from 10 Myr to 5 Gyr. Much of thestellar population represented in the continua was probably formedbefore the merger and represents the progenitor galaxies.
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The Relation between Dynamics and Star Formation in Barred Galaxies
We analyze optical and near-infrared data of a sample of 11 barredspiral galaxies, in order to establish a connection between starformation and bar/spiral dynamics. We find that 22 regions located inthe bars and 20 regions in the spiral arms beyond the end of the barpresent azimuthal color/age gradients that may be attributed to starformation triggering. Assuming a circular motion dynamic model, wecompare the observed age gradient candidates with stellar populationsynthesis models. A link can then be established with the disk dynamicsthat allows us to obtain parameters like the pattern speed of the bar orspiral as well as the positions of resonance radii. We subsequentlycompare the derived pattern speeds with those expected from theoreticaland observational results in the literature (e.g., bars ending nearcorotation). We find a tendency to overestimate bar pattern speedsderived from color gradients in the bar at small radii, away fromcorotation; this trend can be attributed to non-circular motions of theyoung stars born in the bar region. In spiral regions, we find that ~50%of the color gradient candidates are "inverse," i.e., with the directionof stellar aging contrary to that of rotation. The other half of thegradients found in spiral arms have stellar ages that increase in thesame sense as rotation. Of the nine objects with gradients in both barsand spirals, six (67%) appear to have a bar and a spiral with similar? p , while three (33%) do not.
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Dark spot, spiral waves and the SW Sextantis behaviour: it is all about UX Ursae Majoris
We present an analysis of time-resolved, medium-resolution opticalspectroscopic observations of UX Ursae Majoris (UX UMa) in the blue(3920-5250 Å) and red (6100-7200 Å) wavelength ranges thatwere obtained in 1999 April and 2008 March, respectively. The observedcharacteristics of our spectra indicate that UX UMa has been indifferent states during those observations. The blue spectra are verycomplex. They are dominated by strong and broad single-peaked emissionlines of hydrogen. The high-excitation lines of He II ?4686 andthe Bowen blend are quite strong as well. All the lines consist of amixture of absorption and emission components. Using Doppler tomography,we have identified four distinct components of the system: the accretiondisc, the secondary star, the bright spot from the gas stream/discimpact region and the unique compact area of absorption in the accretiondisc seen as a dark spot in the lower left-hand quadrant of thetomograms. In the red wavelength range, both the hydrogen (H?) andneutral helium (He I ?6678 and He I ?7065) lines wereobserved in emission and both exhibited double-peaked profiles. Dopplertomography of these lines reveals spiral structure in the accretiondisc, but in contrast to the blue wavelength range, there is no evidencefor either the dark spot or the gas stream/disc impact region emission,while the emission from the secondary star is weak. During theobservations in 1999, UX UMa showed many of the defining properties ofthe SW Sextantis stars. However, all these features almost completelydisappeared in 2008. We have also estimated the radial velocitysemi-amplitudes K1 and K2 and evaluated the systemparameters of UX UMa. These estimates are inconsistent with previousvalues derived by means of analysis of white dwarf eclipse features inthe light curve in different wavelength ranges.
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LoCuSS: first results from strong-lensing analysis of 20 massive galaxy clusters at z = 0.2
We present a statistical analysis of a sample of 20 strong lensingclusters drawn from the Local Cluster Substructure Survey, based onhigh-resolution Hubble Space Telescope imaging of the cluster cores andfollow-up spectroscopic observations using the Keck-I telescope. We usedetailed parametrized models of the mass distribution in the clustercores, to measure the total cluster mass and fraction of that massassociated with substructures within R <= 250kpc. These measurementsare compared with the distribution of baryons in the cores, as traced bythe old stellar populations and the X-ray emitting intracluster medium.Our main results include: (i) the distribution of Einstein radii islognormal, with a peak and 1? width of = 1.16 +/- 0.28;(ii) we detect an X-ray/lensing mass discrepancy of = 1.3 at 3? significance -clusters with larger substructure fractions displaying greater massdiscrepancies, and thus greater departures from hydrostatic equilibriumand (iii) cluster substructure fraction is also correlated with theslope of the gas density profile on small scales, implying a connectionbetween cluster-cluster mergers and gas cooling. Overall our results areconsistent with the view that cluster-cluster mergers play a prominentrole in shaping the properties of cluster cores, in particular causingdepartures from hydrostatic equilibrium, and possibly disturbing coolcores. Our results do not support recent claims that large Einsteinradius clusters present a challenge to the cold dark matter paradigm.
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Catalogue of Ap, HgMn and Am stars
We present a catalogue of 8205 known or suspected Ap, HgMn and Am stars.This paper is a major update of our first edition of the catalog of Apand Am stars and includes revised identifications, additional stars andrevised information obtained from the literature.Catalogue (full Table 1) is only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/498/961
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Spiral Density Wave Triggering of Star Formation in SA and SAB Galaxies
Azimuthal color (age) gradients across spiral arms are one of the mainpredictions of density wave theory; gradients are the result of starformation triggered by the spiral waves. In a sample of 13 spiralgalaxies of types A and AB, we find that ten of them present regionsthat match the theoretical predictions. By comparing the observedgradients with stellar population synthesis models, the pattern speedand the location of major resonances have been determined. The resonancepositions inferred from this analysis indicate that nine of the objectshave spiral arms that extend to the outer Lindblad resonance; for one ofthe galaxies, the spiral arms reach the corotation radius. The effectsof dust, and of stellar densities, velocities, and metallicities on thecolor gradients are also discussed.
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Strong lensing in Abell 1703: constraints on the slope of the inner dark matter distribution
Properties of dark matter haloes can be probed observationally andnumerically, and comparing both approaches provides ways to constraincosmological models. When it comes to the inner part of galaxy clusterscale haloes, interaction between the baryonic and the dark mattercomponent is an important issue that is far from being fully understood.With this work, we aim to initiate a program coupling observational andnumerical studies to probe the inner part of galaxy clusters. In thisarticle, we apply strong lensing techniques on Abell 1703, a massiveX-ray luminous galaxy cluster at z = 0.28. Our analysis is based onimaging data from both the space and ground in 8 bands, complemented bya spectroscopic survey. Abell 1703 is rather circular from the generalshape of its multiply imaged systems and is dominated by a giantelliptical cD galaxy in its centre. This cluster exhibits a remarkablebright central ring formed by 4 images at z_spec = 0.888 only 5-13arcsec away from the cD centre. This unique feature offers a rarelensing constrain for probing the central mass distribution. The stellarcontribution from the cD galaxy (˜1.25 × 1012Msun within 30 kpc) is accounted for in our parametric massmodelling, and the underlying smooth dark matter component distributionis described using a generalized nfw profile parametrized with a centrallogarithmic slope ?. The rms of our mass model in the image planeis equal to 1.4 arcsec. We find that within the range whereobservational constraints are present (from 20 kpc to 210 kpc),? is equal to 1.09+0.05-0.11 (3?confidence level). The concentration parameter is equal toc200 3.5, and the scale radius is constrained to be largerthan the region where observational constraints are available(rs =730^+15-75 kpc). The 2D mass is equal to {M}(210 kpc) = 2.4 × 1014 Msun. However, wecannot draw any conclusions on cosmological models at this point sincewe lack results from realistic numerical simulations containing baryonsto make a proper comparison. We advocate the need for a large sample ofwell observed (and well constrained) and simulated unimodal relaxedgalaxy clusters in order to make reliable comparisons and to potentiallyprovide a test of cosmological models.Appendix A is only available in electronic form at http://www.aanda.org
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Spectral observations of FBS blue stellar objects in the zone δ = + 35°
The next list of spectral data on blue stellar objects (BSOs) ispresented. 58 FBS objects in a zone with a central declination δ =+ 35° were observed with the 2.6-m telescope at the ByurakanObservatory during 1990 1991. In addition, 3 objects were observed (3CCD spectra were obtained) with the BAO 2.6-m and OHP 1.93-m telescopesin 1997 2000 using modern instrumentation. 9 white dwarfs, 47 hotsubdwarfs, and 2 HBB stars have been discovered. Spectra of the 10 mostinteresting objects are given.
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Spectral observations of blue stellar objects from FBS in the zone δ =+39°
Spectral observations of blue stellar objects from FBS are reported forthe purpose of classifying them, discovering interesting new objects,and studying the FBS sample as a whole. 59 FBS objects in the zone withcentral declination δ =+39° were observed with the 2.6-mtelescope at the Byurakan Observatory during 1987 1991. The images havebeen digitized with a professional scanner and processed by MIDAS in away similar to CCD spectra. In addition, 4 objects were observed withthe BAO-2.6 and OHP-1.93 telescopes using modern techniques during 19972000. 3 white dwarfs, 45 hot subdwarfs, 4 HBB stars, and 2 class F starswere discovered. Spectra of 20 of the most interesting objects areshown.
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A possible orbital period for the dwarf nova V1101 AQL
We have performed a Discrete Fourier Transform on 136 CCD B, V and Rframes of the Z Cam-type dwarf nova V1101 Aql. Our analysis indicates aspossible orbital period P_orb =3D 3() h.46, though we cannot exclude thealias at 4() h.00. We estimate the distance to the system to be about300 pc. We possibly discovered a bright bow-shaped nebulosity around theobject. Based on observations obtained at the European SouthernObservatory, La Silla, Chile and at the Osservatorio Astrofisico diAsiago, Italy.
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A Catalog of Candidate Field Horizontal-Branch and A-Type Stars. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJS..103..433B&db_key=AST
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Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
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The nebular phase spectra of SN1993J
From June 19 to August 27, using the 2.16m telescope in the BeijingAstronomical Observatory, we obtained some low resolution spectra ofSN1993J. The forbidden emission lines (O1). (Ca2) were very strong anddominated the spectra. However, the Halpha and He lines werevery weak. Many fine structures appeared in the Halpha and(O1) lines. We found that the supernova had entered the nebular phaseand strong instability and chemical mixing had occurred in the ejecta.
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General catalogue of AP and AM stars
A catalog of all the known Ap and Am stars, containing a total of 6684objects, was prepared. The few stars that were wrongly considered as Apor Am star are noted as well as some others for which their identity asAp or Am stars is not yet well established. The catalog gives theidentificators and the main observational data for each star, includingthe magnitude, color, spectral type, duplicity, periodicity, magneticfield, and projected rotational velocity.
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Markarian 907 : an interacting system of galaxies.
Not Available
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On the spectral variability of galaxy No. 163.
The spectral variability of the Seyfert-type galaxy No. 163 fromKazarian's list is shown.
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The interacting galaxy NGC 5514 - A system with off-nuclear activity
Multicolor CCD images and long slit spectroscopic data for NGC 5514 arepresented. This galaxy is composed of two interacting disk systems withmorphological similarities to the antennae NGC 4038/39. Two regions ofline emission of H II and LINER type are found. Notably, these regionsare located in the outer parts of the galaxy, whereas the nuclear regionis nearly devoid of line emission.
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Correlation of broad and narrow diffuse band features Evidence for molecular carriers
Spectra of early-type stars in several heavily reddened OB associationsare used to study broad diffuse bands in the range from 5700 to 6300angstroms. The features at 5778 angstroms and 6170 angstroms correlatedwell with narrower lines in their vicinity. The 5795-angstrom band isnot correlated with the overlapping line at 5797 angstroms but appearsto be part of a structure which includes 5780- and 5778-angstromfeatures. The profile of the band at 6170 angstroms is smooth andfeatureless; the shape of the 5778-angstrom band is more complex withthree well-defined peaks. The explanation for the observed correlationpatterns can be found more easily within molecular theories of theorigin of bands. It is shown that vibronic interactions in individualmolecules or a superposition of narrower lines from slightly modifiedbut closely related species can give rise to broad bands, such as 6170and 5778 angstroms.
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Numerical convolution photometry - an example using the Stromgren four-color system
The method of numerical convolution photometry is presented. This methodis then applied to spectrophotometric observations of hot blue starsusing the Strömgren four-color photometric system. New colorrelations are discussed as well as their usefulness in determining someintrinsic properties of the program stars, in particular, the whitedwarfs. A discussion of the errors involved and the accuracy of thismethod is also included.
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Calibration of the Lick red CCD bandpasses
Red bandpasses indigenous to the Lick Observatory CCD imaging andphotometry are defined and described. A set of primary calibrationstandards which define the magnitude zero points is presented. Colorequations, relating these bandpasses to the other, commonly usedphotometric systems are evaluated by numerical integration of stellarspectra, and compared to the real data. It is estimated that the presentcalibration is accurate and consistent to about 2-3 percent as amagnitude predictor, if the primary standards are used; this accuracy isonly about 3-5 percent if VR photometry is used for calibration, andonly about 5-8 percent if BV photometry is used. (These estimates do notinclude the errors of measurement). This is sufficient for mostscientific applications of data taken in these bandpasses, although itmay be improved somewhat in a future work.
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Spectral energy distributions of standard stars of intermediate brightness. II.
Abstract image available at:http://adsabs.harvard.edu/abs/1977ApJ...218..767S
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Catalog of spectrophotometric scans of stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJS...32....7B&db_key=AST
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The Nature of Faint Blue Stars in the Halo. II
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..157G&db_key=AST
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The Evolutionary Status of the Blue Halo Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJS...26...37N&db_key=AST
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A Photometric Classification of the Feige Blue Stars
Abstract image available at:http://adsabs.harvard.edu/abs/1970PASP...82.1305G
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Hγ Observations for Fourteen of Feige's Faint Blue Stars
Abstract image available at:http://adsabs.harvard.edu/abs/1968PASP...80..238W
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The Nature of the Faint Blue Stars
Abstract image available at:http://adsabs.harvard.edu/abs/1966ApJ...144..496G
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The Colors of Some High-Latitude Blue Stars.
Not Available
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An Atlas of Indentification Charts for 113 Blue Stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1959ApJ...129..600F
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A Search for Underluminous Hot Stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1958ApJ...128..267F
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INHABITED SKY
