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The qWR star HD 45166 . I. Observations and system parameters
The binary star HD 45166 has been observed since 1922but its orbital period has not yet been found. It is considered apeculiar Wolf-Rayet star, and its assigned classification has varied.For this reason we included the object as a candidate V Sge star andperformed spectroscopy in order to search for its putative orbitalperiod. High-resolution spectroscopic observations show that thespectrum, in emission and in absorption, is quite rich. The emissionlines have great diversity of widths and profiles. The full widths athalf maximum vary from 70 km s-1 for the weakest lines up to370 km s-1 for the most intense ones. The hydrogen and heliumlines are systematically broader than the CNO lines. Assuming thatHD 45166 is a double-line spectroscopic binary, itpresents an orbital period of P = 1.596 ± 0.003 day, with aneccentricity of e = 0.18 ± 0.08. In addition, a search forperiodicity using standard techniques reveals that the emission linespresent at least two other periods, of 5 and 15 h. The secondary starhas a spectral type of B7 V and, therefore, should have a mass of aboutM2 = 4.8 ~Mȯ. Given the radial velocityamplitudes, we determined the mass of the hot (primary) star asM1 = 4.2 ± 0.7~Mȯ and the inclinationangle of the system, i = 0.77° ± 0.09°. As theeccentricity of the orbit is non zero, the Roche lobes increase anddecrease as a function of the orbital phase. At periastron, thesecondary star fills its Roche lobe. The distance to the star has beenre-determined as d = 1.3 ± 0.2 kpc and a color excess ofE(B-V)=0.155~±~0.007 has been derived. This implies an absolute Bmagnitude of -0.6 for the primary star and -0.7 for the B7 star. Wesuggest that the discrete absorption components (DACs) observed in theultraviolet with a periodicity similar to the orbital period may beinduced by periastron events.Based on observations made at the 1.5 m ESO telescope at La Silla, Chile, and at Laboratório Nacional de Astrofísica/CNPq, Brazil.Tables 2-5 are only available in electronic form 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/444/895
| The Multiple Spectroscopic and Photometric Periods of DI Crucis (WR 46)
In an effort to determine the orbital period of the enigmatic star DICru (HD 104994, WR 46), we made photometric and spectroscopicobservations of this object between 1996 and 2002. Both photometric andspectroscopic characteristics are quite complex. The star is highlyvariable on short (few hour) as well as on long (few month) timescales.The optical spectrum is rich in strong emission lines of high-ionizationspecies such as He II, N IV, N V, and O VI. Weak emission of C III isalso present. Emission lines have been compiled and identified from theultraviolet to the infrared. In the UV, emission of O V and N IV is alsoobserved, together with very weak emission of C IV. The N Vλλ4603, 4619/He II λ4686 line ratios vary by asignificant amount from night to night. Temporal variance spectrumanalysis shows that the He II λ4686 line has P Cyg-like variableabsorption, while N V λλ4603, 4619 lines have a strong andbroad variable component due to the continuum fluorescence from a source(stellar atmosphere/optically thick wind) of variable temperature. Wealso show that the object has variable degree of ionization, probablycaused by wind density variation. The star presents multiple periods inradial velocity and photometry. From our data we derived a main radialvelocity period of 0.3319 days with an amplitude of K=58 kms-1. This period is similar to the value found by Marchenkoand coworkers. When at intermediate brightness, this period is also seenin the photometric measurements. When the star is at bright phase, thephotometric variations do not present the same period. Photometricperiods ranging from 0.154 to 0.378 days are present, consistent withobservations reported by other authors. Besides the 0.3319 day period,other spectroscopic periods are also seen. On distinct epochs, theperiods are different; Marchenko et al. interpreted the 0.3319 dayperiod as the orbital one. Although we do not discard this possibility,the true binary nature (e.g., long-term coherence or detection of asecondary star) has not yet been demonstrated. DI Cru is a Population IWR object. Given the similarities (e.g., multiple periods likely due tononradial oscillations), it could be interpreted as a luminouscounterpart of the qWR star HD 45166.Based on observations made at the Observatório do Pico dosDias/LNA, Brazil, and at the 1.5 m ESO telescope at La Silla, Chile.
| Magnetorotational Supernova Explosions and the Formation of Neutron Stars in Close Binary Systems
The formation of neutron stars in the closest binary systems (Porb<12 h) gives the young neutron star/pulsar a high rotationalvelocity and energy. The presence of a magnetic field of 3×10113×1013 G, as is observed for radio pulsars, enables the neutronstar to transfer 1051 erg of its rotational energy to the envelopeover a time scale of less than an hour, leading to a magnetorotationalsupernova explosion. Estimates indicate that about 30% of all type-Ib,csupernovae may be the products of magnetorotational explosions. Youngpulsars produced by such supernovae should exhibit comparatively slowrotation (P rot>0.01 s), since a large fraction of their rotationalangular momentum is lost during the explosion. The magnetorotationalmechanism for the ejection of the envelope is also reflected by theshape of the envelope. It is possible that the Crab radio pulsar is anexample of a product of a magnetorotational supernova. A possiblescenario for the formation of the close binary radio pulsar discoveredrecently by Lyne et al. is considered.
| WR 7a: a V Sagittae or a qWR star?
The star WR 7a, also known as SPH 2, has a spectrum that resembles thatof V Sagittae stars although no OVI emission has been reported. TheTemporal Variance Spectrum - TVS - analysis of our data shows weak butstrongly variable emission of OVI lines which is below the noise levelin the intensity spectrum.Contrary to what is seen in V Sagittae stars, optical photometricmonitoring shows very little, if any, flickering. We found evidence ofperiodic variability. The most likely photometric period isPphot= 0.227(+/-14) d, while radial velocities suggest aperiod of Pspec= 0.204(+/-13) d. One-day aliases of theseperiods can not be ruled out. We call attention to similarities with HD45166 and DI Cru (= WR 46), where multiple periods are present. They maybe associated to the binary motion or to non-radial oscillations.In contrast to a previous conclusion by Pereira et al., we show that WR7a contains hydrogen. The spectrum of the primary star seems to bedetectable as the NV 4604Åabsorption line is visible. If so, itmeans that the wind is optically thin in the continuum and that it islikely to be a helium main sequence star.Given the similarity to HD 45166, we suggests that WR 7a may be a qWR -quasi Wolf-Rayet - star. Its classification is WN4h/CE in the Smith,Shara & Moffat three-dimensional classification system.
| Luminous binary supersoft X-ray sources: Optical colors and absolute magnitudes
An analysis of the color indices and absolute magnitudes MV0of the ``classical'' supersoft X-ray binary sources (SSXBs), the VSge-type stars (VSs), the symbiotic SSXBs, and the classical novae inthe soft X-ray phase is presented. This approach can help comparing theproperties and configuration of the reprocessing medium in theindividual systems. The range of MV0 of the individualobjects is very large, from MV0=8.5 to MV0=-4,most systems having MV0<2. The objects with the orbitalperiod Porb<4 days tend to possess brighter MV0with the increasing Porb. The same trend is apparent also forMU0. There is no systematic difference between the classicalSSXBs and the VSs, as regards their MV0 and MU0.The soft X-ray phase of the novae V 1974 Cyg and V 382 Vel occurred atsignificantly brighter MV0 than those of most other SSXBswhile MV0 of the recurrent nova U Sco was comparable to theSSXBs of the comparable Porb. We showed that the luminosityof the reprocessing medium in the symbiotic SSXBs does not increase muchwith Porb, when compared with the luminosity of the classicalSSXBs and VSs; this speaks against large disks in these symbiotics. Theclassical SSXBs and the VSs have colors very similar each to other andform closed groups in the color-color diagrams. A Balmer jump occursfrequently in emission as inferred from the colors. The correlationbetween the bolometric luminosity, determined from the X-ray spectra andMV0 or MU0 of all kinds of the SSXBs is ratherweak, but resolvable, and is more prominent for MU0. Theimplications for the reprocessing medium are discussed.Tables 2 and 3 are only available in electronic form athttp://www.edpsciences.org
| A multifrequency study of the hot subdwarf population.
Not Available
| A Second Catalog of Orbiting Astronomical Observatory 2 Filter Photometry: Ultraviolet Photometry of 614 Stars
Ultraviolet photometry from the Wisconsin Experiment Package on theOrbiting Astronomical Observatory 2 (OAO 2) is presented for 614 stars.Previously unpublished magnitudes from 12 filter bandpasses withwavelengths ranging from 1330 to 4250 Å have been placed on thewhite dwarf model atmosphere absolute flux scale. The fluxes wereconverted to magnitudes using V=0 for F(V)=3.46x10^-9 ergs cm^-2 s^-1Å^-1, or m_lambda=-2.5logF_lambda-21.15. This second catalogeffectively doubles the amount of OAO 2 photometry available in theliterature and includes many objects too bright to be observed withmodern space observatories.
| Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
| 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.
| Infrared flux excesses from hot subdwarfs. II. 72 more objects
In our search, started in February, 1994, for JHK excess fluxes amongthe hot subdwarf population as an indicator for the presence of binarycompanions, results for 72 more hot objects (=63 hot subdwarfs + 1Horizontal Branch B star + 7 white dwarfs + 1 non-subdwarf object)observed with the Carlos Sanchez CVF IR photometer (in June and October,1994), are presented. The exact number of binary hot subdwarfs hasgained renewed importance after the recent discovery of pulsators withG-F companions. The total number of candidates we propose may help toset some constraints; for example, out of 41 objects with excesses, 13may have G-type binary companions. From our new sample, 14 discoveriesof binary candidates have been found: BD+25 4655, Feige 108, HD 4539, HD149382, HD 216135, KPD 2109+440, LSI+63 198, LSIV+10 9, LSV+22 38, PG0011+221, PG 0116+242, PG 0314+103, PG 2151+100 and TON 139. Besides, 2more from reanalysis of February, 1994, data - BD+37 1977 and BD+481777, may now be found to be IR excess candidates. Two suspectedbinaries, PB 8555 and SB 7, are also confirmed. By fitting \cite[Kurucz(1993)]{kur93} model spectra and assuming zero-age main sequencecompanions, we find upper limits on the subdwarf gravities. Thedistributions of upper limits on log(g), mostly between about 5.25 and6.5, are nearly identical for both sdBs and sdOs. Figure~1 is onlyavailable in the electronic version of the paper(http://www.edpsciences.com)
| Catalogue of stars in the northern Milky Way having H-alpha in emission
Not Available
| 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.
| Far-ultraviolet stellar photometry - A field in Monoceros
FUV photometry of stars in a field in Monoceros in the wavelength rangefrom 1230 to 1600 A has been carried out using data from anelectrographic Schmidt camera carried on a sounding rocket. Ultravioletmagnitudes were extracted for 602 objects in the field. Fifty-eightpercent were tentatively identified with visible stars using the SIMBADdata base while another 25 percent are blends of objects too closetogether to separate with our resolution. Eleven of the UV objectscoincide with parts of the star clusters NGC 2169, NGC 2244, and NGC2264 in which individual stars cannot be resolved. As in previousstudies, the majority of the identified ultraviolet sources areidentified with early-stars. However, there are a significant number forwhich no such identification was possible, and we suggest that many ofthese are nearby white dwarfs.
| Broad-band photometry of selected southern ultraviolet-bright stars.
Not Available
| The ultraviolet variability of HD 45166 (qWR + B8 V) - Evidence for stellar wind radiative instabilities
High-resolution IUE spectroscopy of the low-mass qWR star HD 45166,obtained at several epochs during 1980-1988, reveals a complex patternof variability in its stellar wind emission lines, P Cygni profiles, andhighly ionized photospheric absorption spectrum. The most intensiveobservations, obtained during a 36 hr continuous run in February 1988,show the presence of discrete absorption components (DACs) in the C IV1550 resonance doublet. These DACs can blend to give the appearance of awell-developed P Cygni absorption profile seen at some other times,roughly doubling the column density of the ground state C(3+) ions inthe wind. In the 1988 spectra, two principal features are seen, at about-950 km/s and -750 km/s, with column densities of about 14.0 and 14.7dex/sq cm, respectively. Both features migrate in velocity withaccelerations of about 140 cm/sq sec, implying a recurrence time scaleof about 1.6 days and a lifetime of about 3 days for the DACs. Astriking characteristic of the acceleration is its slowness. The patternof DAC variability in HD 45166 is similar to that found for O-type starsand provides further evidence that the DACs are not mass-conservingfeatures but rather that a given feature is formed by different materialat different times. It is concluded that the C IV DAC variabilityobserved in HD 45166 results from structural changes in the wind arisingfrom radiative instabilities.
| Software for selecting processing, and analyzing IUE data
A software system based on Interactive Data Language (IDL) is described.It includes a database management system, a technique to acquire datafrom the archives, an IUE observation processing system, and analysissoftware. Each of these elements is fully integrated within IDL, whichmakes for versatility, a high degree of control by the user, and forsimplicity. The database management system contains catalogs of all themajor astronomical satellites (IUE, Einstein, Exosat, and IRAS) as wellas other astronomical catalogs.
| Stellar wind variations in HD 45166: The continuing story
High resolution SWP IUE spectra of HD 45166 (qWR+B8V) obtained over a 36hr continuous run, together with earlier observations, reveal 2 distinctmodes of UV variability in this object. Gross, epoch-linked changes areseen in the strengths of the qWR emission lines, accompanied by largechanges in its highly ionized photospheric absorption spectrum. Rapid(hours) variability in strong, multiple, high velocity, wind discreteabsorption components (DAC), in the CIV lambda 1550 resonance lines,which superpose to give the appearance of a broad P Cygni absorptionprofile at many epochs is also observed. These multiple DAC's (often atleast 3 are seen) propagate in velocity, from 0.6 to 1.0 v inf, on atimescale of 1 day, implying an acceleration of 180 cm/s comparable tothat seen in O-type stars.
| IUE studies of mass loss phenomena in hot stars
The determination of mass loss rates and wind velocities in a largesample of hot stars with IUE; the discovery of mass loss and winds inSdO stars; UV studies of mass loss in OB stars in the Magellanic Cloudsand beyond; stimuli to the development of improved radiation pressurewind models; and the discovery of substantial stellar wind variability,epitomized by the occurrence and variation of wind discrete absorptioncomponents in a wide range of stellar types are discussed. This progressresults from the combination of high spectral sensitivity, wavelengthmultiplexing, observatory nature, and longevity of IUE, important infacilitating detailed variability studies of individual sources over awide range of timescales.
| A catalogue of spectroscopically identified hot subdwarf stars.
Not Available
| Gross ultraviolet spectral variability in HD 45166 (qWR + B8V)
High resolution IUE SWP spectra of HD 45166 were secured at variousepochs over 1980 to 1983. Data confirm dramatic variations in the qWRP-Cygni profiles and emission lines reported by Willis and Stickland(1983), and reveal large changes also in the qWR highly ionizedphotospheric absorption spectrum. No changes are apparent in theUV-optical continuum. A common physical origin for the qWR photosphericand stellar wind changes, which may be linked to variations in theionizing EUV flux into both stellar regions, is suggested.
| Absolute spectrophotometry of northern Wolf-Rayet stars - How similar are the colors?
Spectrophotometry of 55 Wolf-Rayet stars is presented in order todetermine the dependence of their intrinsic colors on spectral subtype.These data are the first with both sufficient photometric precision andspectral resolution to determine magnitudes and colors withoutcontamination from emission lines. It is found that the effect ofemission lines on previous ubvr filter photometry did occasionallyamount to as much as 0.3 mag in the colors. These data do not confirmearlier reports of ultraviolet excesses for WN stars, nor do theysupport the claim of differences in colors for WN and WC types. Thedifferences in the intrinsic colors of W-R stars from subtype to subtypeis small compared to the considerable variation present among stars ofthe same subtype. Despite the improved accuracy in determining thecontinuum colors, reddening-free indices still show scatter far inexcess of the observational uncertainties, particularly at shorterwavelengths.
| The enigmatic composite system HD 45166-B8V + qWR or SdO
High- and low-resolution IUE ultraviolet spectroscopic observations ofthe binary system HD 45166, previously classified as qWR + B8 V,obtained at several epochs are presented. The UV spectra show aphotospheric absorption spectrum from highly ionized species like Fe v,which with the observation of B8 V absorptions in the visible, confirmsthe binary nature of the system. UV data obtained at different epochsshow gross changes in the strengths of comparatively narrow emissionlines in N IV, C III and He II. C IV 1550 shows a P-Cygni profileindicating a significant stellar wind from the hot object in the system,with v(infinity) of about 1200 km/s. An analysis of the UV and visiblecontinuum, which shows no apparent epoch variations, yields thefollowing parameters for the hot object: M(v) = -0.21, T(eff) = 60,000K, log L/L(solar) = 3.84, R = 0.77 R(solar) and M = 0.5 M(solar). It issuggested that the hot stellar component may be an SdO rather than a qWRstar. The cause of the observed variability in the emission linesremains an enigma.
| A survey of ultraviolet objects
An all-sky survey of ultraviolet objects is presented together with astatistical analysis that leads to the conclusion that there is asignificantly higher population of hot subdwarfs lying below themain-sequence than hitherto thought. The distribution of all ultravioletobjects, main sequence ultraviolet objects, and MK unclassifiedultraviolet objects are shown in galactic coordinates, and the absolutemagnitudes and color-color diagrams for these groups are presented.Scale heights are derived, giving values similar to planetary nebulaefor the hottest groups.
| Variable Stars in the Northern Luminous Stars Catalogues
Not Available
| HD 45166 - A dwarf in Wolf-Rayet clothing
A coarse analysis of the hydrogen and helium lines of HD 45166 isperformed which supports the interpretation that the object is a binarycomposed of a late B star and a star of approximately one solar radiuswith a continuous energy distribution very much like that of Zeta Pup.It is surrounded by an envelope expanding at 150 km/s formed by massejection at a rate of only 5 hundred-millionths of a solar mass per yr.The small size and low ejection velocity give densities of He II in theenvelope of about 100 billion per cu cm. The envelope environment isthus much like that of a normal Wolf-Rayet star, which it mimics withremarkable consistency.
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Observation and Astrometry data
| Constellation: | Μονόκερως |
| Right ascension: | 06h26m19.15s |
| Declination: | +07°58'28.1" |
| Apparent magnitude: | 9.942 |
| Proper motion RA: | -2.4 |
| Proper motion Dec: | -2.3 |
| B-T magnitude: | 9.794 |
| V-T magnitude: | 9.93 |
Catalogs and designations:
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