The infrared void in the Lupus dark clouds revisited: a polarimetric approach
The results of B-band CCD imaging linear polarimetry obtained for starsfrom the Hipparcos catalogue are used to re-examine the distribution ofthe local interstellar medium towards the IRAS 100-μm emission voidin the Lupus dark clouds. The analysis of the obtainedparallax-polarization diagram assigns to the dark cloud Lupus1 adistance between 130 and 150pc and assures the existence of a low columndensity region coincident with the observed infrared void. Moreover,there are clear indications of the existence of absorbing material atdistances closer than 60-100pc, which may be associated with theinterface boundary between the Local Bubble and its neighbourhood LoopIsuperbubble.
|
New optical polarization measurements of quasi-stellar objects. The data
New linear polarization measurements (mainly in the V band) arepresented for 203 quasi-stellar objects (QSOs). The sample is made up of94 QSOs located in the North Galactic Pole (NGP) region and of 109 QSOsin the South Galactic Pole (SGP) region. First time measurements havebeen obtained for 184 QSOs. Among them, 109 known radio-emitters, 42known Broad Absorption Line (BAL) QSOs, and 1 gravitationally lensedquasi-stellar object. We found high polarization levels (p > 3%) for12 QSOs, including the BAL QSO SDSS J1409+0048. For10 objects, measurements obtained at different epochs do exist. Two ofthem show evidence for variability: the highly polarized BL Laccandidate PKS 1216-010 and the radio sourcePKS 1222+037.Based on observations collected at the European Southern Observatory(ESO, La Silla and Paranal). Table 4 is only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/757
|
Spectropolarimetry of the borderline Seyfert 1 galaxy ESO 323-G077
We report the detection of high linear polarization in the brightSeyfert 1 galaxy ESO 323-G077. Based on opticalspectropolarimetry with FORS1 at the VLT we find a continuumpolarization which ranges from 2.2% at 8300 Å to 7.5% at 3600Å. Similar amounts of linear polarization are found for the broademission lines, while the narrow lines are not polarized. The positionangle of the polarization (theta =84o) is independent of thewavelength and found to be perpendicular to the orientation of theextended [O III] emission cone of this galaxy. Within the standard modelof Seyfert nuclei the observations can be well understood assuming thatthis AGN is observed at an inclination angle where the nucleus ispartially obscured and seen mainly indirectly in the light scattered bydust clouds within or above the torus and the illuminated inner edge ofthe dust torus itself. Hence we conclude that ESO 323-G077 is aborderline Seyfert 1 galaxy which can provide important information onthe geometric properties of active nuclei.Based on observations obtained at the ESO VLT UT1 (Antu) at CerroParanal, Chile (ESO program 66.B-0063).
|
New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.
|
VLT-spectropolarimetry of the high-polarization Seyfert 1 galaxy Fairall 51
We present high-precision optical spectropolarimetry of the Seyfert 1galaxy Fairall 51 (F51) taken with FORS1 at the VLT.The observed spectrum shows unpolarized and linearly polarizedcomponents. The AGN continuum and the broad lines show (after correctionfor the Galactic interstellar polarization and the light contribution ofthe F51 host galaxy) a practically identical amountof intrinsic polarization ranging from 5% in the red to 13% in the UV.The narrow lines are unpolarized or show only little intrinsicpolarization. The observed AGN continuum and the broad line radiationcan be explained by a combination of reddened (and attenuated) directlight and scattered light reflected from an optically thin dust region.Hence, within the framework of the unification scheme of AGN, theSeyfert 1 galaxy F51 appears to be an example of aborderline Seyfert 1/Seyfert 2 case where the nucleus is partiallyobscured like for other type 1 AGN with high intrinsic scatteringpolarization. It is found that the scattering region inF51 is located far from the BLR and the continuumsource. Thanks to this special scattering configuration, we were able tostudy the kinematics (line profiles) of the broad line region from twodifferent viewing angles, one along the line of sight (in total light)and one via the scattering region (in polarized light). The lineprofiles in polarized and total light are found to be indistinguishableto a very high accuracy, strongly indicating that the velocity field ofthe F51 BLR is essentially spherically symmetric.Based on observations obtained at the ESO VLT UT1 (Antu) at CerroParanal, Chile (ESO program 63.P-0074).
|
Observations of OB-stars at the former Leiden Southern Station
About 700 stars, mostly OB-stars, were observed by the author at theformer Leiden Southern Station at Hartebeespoortdam, South Africa, inthe observing seasons 1965, 1968, 1969, 1974, 1977, 1978. Observationswere made in the five channels of the Walraven photometric system. Dueto weathering of the telescope mirror the W channel gave no reliableresults for the faintest stars (m = 11 mag); in these cases the U-Wcolour index is not given. The change in sensitivity in the V channel,supposedly having occurred in 1968, was not recognised. Table~5 is onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/369/527
|
Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
|
Optical polarization of 47 quasi-stellar objects: The data
New broad-band linear polarization measurements are presented for asample of 47 QSOs which includes 27 broad absorption line QSOs and 2gravitational lens candidates. Tables 3 and 4 are also available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Based onobservations collected at the European Southern Observatory (ESO, LaSilla).
|
Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
|
UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
|
Spectropolarimetry of the Circinus galaxy
High quality 4500--6800 Angstroms spectropolarimetric observations ofthe Circinus galaxy are reported. These show polarized and relativelybroad (FWHM ~ 3300 km/s) Hα (as well as marginal Hβ ) arisingfrom a <3'' (<60 pc) region centered on the nucleus and coincidentwith the the peak of the narrow line region. Broad Hα might alsobe present ~ 8'' (160 pc) SE from the nucleus and close to the dustlane, but the result is only marginal and should be verified by highers/n data. The continuum is dominated by stellar emission with <=3%contribution from the scattered AGN continuum, and all the light (i.e.all the stellar continuum and narrow lines) is polarized, most probablyby transmission through and scattering by dust in the disk. The data arecompatible with a simple model where the scattered broad lines and AGNemission are quite polarized (P ~ 25%) but account for only 1% of theobserved continuum. The scattered broad Hα has an equivalent widthW_lambda =~ 400 Angstroms, a flux similar to the narrow Hα and aluminosity =~ 5 10(5) L_sun. Assuming an efficiency of 1% for the BLRmirror, the intrinsic luminosity of the broad Hα is roughly 510(7)L_sun and ~ 0.5% of the FIR luminosity, a ratio similar to those foundin type 1 Seyferts. Specific prediction for future observations are alsopresented. Based on observations collected at the European SouthernObservatory, La Silla, Chile
|
Polarimetry of the ultraviolet continua of southern radio galaxies
This paper reports new B-band polarimetry measurements for fourintermediate-redshift (0.3<z<0.7) southernradio galaxies. Deep optical spectra show that three of these objectsare broad-line radio galaxies, while the fourth is a narrow-line radiogalaxy. Despite the fact that the measurements were made in therest-frame ultraviolet (UV) in each object, and that emission-linecontamination is small, we find that the majority of objects display lowintrinsic continuum polarization. In two of the broad-line objects (PKS1602+01 and PKS 2135-20), this may result from our viewing thebroad-line region directly. The significant polarization measure, andcorresponding polarization orientation, in the narrow-line object PKS2250-41 is most consistent with scattering of light from the activenucleus. We therefore identify a diversity of UV polarization propertiesin powerful radio galaxies at intermediate redshifts. Not all radiogalaxies possess large intrinsic polarizations. Therefore the UVexcesses observed in these objects are unlikely to result solely fromscattered light.
|
A spectroscopic database for Stephenson-Sanduleak Southern Luminous Stars
A database of published spectral classifications for objects in theStepenson-Sanduleak Luminous Stars in the Southern Milky Way catalog hasbeen compiled from the literature. A total of 6182 classifications for2562 stars from 139 sources are incorporated.
|
Optical Polarimetry of the Southern Compact Radio Source PKS:1934-63
We present B-band polarimetry measurements which show significantoptical polarization in the nucleus of the galaxy associated with thesouthern compact radio source PKS 1934 - 63. The polarization E-vectoris within 10^deg^ of the perpendicular to the VLBI radio axis. Theobservations are consistent with dichroic absorption in a dust bandperpendicular to the radio axis, with scattered AGN light, or withnon-thermal emission associated with the compact double radio structure.In the former two cases, the observations support the idea that theoptical emission from compact radio sources is anisotropic, and that the`unified schemes' may apply to compact as well as extended radiosources. Spectropolarimetric observations are required to identify thepolarization mechanism.
|
Uvby-beta observations of 528 type B stars with V between the 8th and 9th magnitude
The paper presents uvby-beta measurements of 528 type B stars selectedfrom the SAO Catalog on the basis of two criteria: the spectral types inthe range B3-B5 and mV between the 8th and the 9th magnitude. Reddeningindependent (c1) values are estimated from the spectral classificationand compared to the observed values. No systematic trend with observed(b-y), H-beta, or spectral type appears to be present, but the range of(c1) residuals is surprisingly large. A rather large part of the starshas small beta values, smaller than for the BIa supergiants. Only twoare classified as O stars and most of them have the suffix e, ne, ornne. Most beta values for the O type stars are slightly above the upperlimit of 2.585 m.
|
An atlas of Hubble Space Telescope photometric, spectrophotometric, and polarimetric calibration objects
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990AJ.....99.1243T&db_key=AST
|
Massive eclipsing binary candidates
New UBV data are provided for 63 southern OB stars which are eitheridentified in the survey by Garrison, Hiltner, and Schild as havingdouble lines or are known from Wood et al. to be eclipsing binaries.Twenty of the stars are known eclipsing variables. Four stars, notpreviously known as eclipsing, have both spectroscopic evidence ofduplicity and significant photometric variations. Several additionalstars have a marginally significant spread in V magnitude.
|
UBV photometry for southern OB stars
New UBV photometry of 1227 OB stars in the southern Milky Way ispresented. For 1113 of these stars, MK spectral types have been reportedpreviously in a comprehensive survey to B = 10.0 mag.
|
MK spectral classifications for southern OB stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977ApJS...35..111G&db_key=AST
|
O stars and supergiants south of declination -53 0.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..116H&db_key=AST
|
A spectral survey of the southern Milky Way 1 : general description and catalogue 1 (l=306 -318 degrees).
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...16..445S&db_key=AST
|
Studies of the Milky Way from Centaurus to Norma. III. OB stars.
Not Available
|
