Magnetic fields of chemically peculiar stars. I. The catalog of magnetic CP stars
This is the first paper of the series dedicated to the analysis of themagnetism of chemically peculiar (CP) stars of the upper Main Sequence.We use our own measurements and published data to compile a catalog ofmagnetic CP stars containing a total of 326 objects with confidentlydetected magnetic fields and 29 stars which are very likely to possessmagnetic field. We obtained the data on the magnetism of theoverwhelming majority of the stars solely based on the analysis oflongitudinal field component B e . The surface magneticfield, B s , has been measured for 49 objects. Our analysisshows that the number of magnetic CP stars decreases with increasingfield strength in accordance with exponential law, and stars with B e exceeding 5kG occur rarely (about 3% objects of ourlist).
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Magnetic-field dependence of chemical anomalies in CP stars
The dependence of the degree of anomaly of parameter Z of Genevaphotometry ( Z0 = Z CP ℒ Z norm.) on theaverage surface magnetic field Bs is analyzed. The Z0 value isproportional to the degree of anomaly of chemical composition. It wasfound that Bs → 0 corresponds Z0 → ‑0.010÷‑0.015, i.e., part of CP stars are virtually devoid of magneticfield, but exhibit chemical anomalies. This effect may be due toselection whereby only objects with strong chemical anomalies areclassified as CP stars, thereby producing a deficit of stars withrelatively weak anomalies. Moreover, CP stars have other sources ofstabilization of their atmospheres besides the magnetic field, e.g.,slow rotation. Formulas relating Z0 to Bs are derived.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
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The Nainital-Cape Survey. II. Report for pulsation in five chemically peculiar A-type stars and presentation of 140 null results
Aims.We search for photometric variability in chemically peculiar A typestars in the northern hemisphere. Methods: .High-speed photometricobservations of Ap and Am star candidates have been carried out fromARIES (Manora Peak, Nainital) using a three-channel fast photometerattached to the ARIES 104-cm Sampurnanand telescope. Results:.This paper presents three new variables: HD 113878, HD 118660 and HD207561. During the time span of the survey (1999 December to 2004January) pulsations of the δ Sct type were also found for the twoevolved Am stars HD 102480 and HD 98851, as reported in Joshi et al.(2002, 2003). Additionally, we present 140 null results of the surveyfor this time span. Conclusions: .The star HD 113878 pulsates witha period of 2.31 h, which is typical of δ Sct stars. HD 118660exhibits multi-periodic variability with a prominent period of nearly 1h. These periods need to be investigated and make HD 118660 aparticularly interesting target for further observations. For HD 207561,a star classified as Am, a probable pulsation with a period of 6 min wasfound in the light curves obtained on two consecutive nights. Both HD102480 and HD 98851 exhibit unusual alternating high and low amplitudemaxima, with a period ratio of 2:1. The analysis of the null resultsconfirms the photometric quality of the Nainital site.
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Evolutionary state of magnetic chemically peculiar stars
Context: .The photospheres of about 5-10% of the upper main sequencestars exhibit remarkable chemical anomalies. Many of these chemicallypeculiar (CP) stars have a global magnetic field, the origin of which isstill a matter of debate. Aims: .We present a comprehensivestatistical investigation of the evolution of magnetic CP stars, aimedat providing constraints to the theories that deal with the origin ofthe magnetic field in these stars. Methods: .We have collectedfrom the literature data for 150 magnetic CP stars with accurateHipparcos parallaxes. We have retrieved from the ESO archive 142 FORS1observations of circularly polarized spectra for 100 stars. From thesespectra we have measured the mean longitudinal magnetic field, anddiscovered 48 new magnetic CP stars (five of which belonging to the rareclass of rapidly oscillating Ap stars). We have determined effectivetemperature and luminosity, then mass and position in the H-R diagramfor a final sample of 194 magnetic CP stars. Results: .We foundthat magnetic stars with M > 3 ~M_ȯ are homogeneouslydistributed along the main sequence. Instead, there are statisticalindications that lower mass stars (especially those with M ≤2~M_ȯ) tend to concentrate in the centre of the main sequence band.We show that this inhomogeneous age distribution cannot be attributed tothe effects of random errors and small number statistics. Our datasuggest also that the surface magnetic flux of CP stars increases withstellar age and mass, and correlates with the rotation period. For starswith M > 3~M_ȯ, rotation periods decrease with age in a wayconsistent with the conservation of the angular momentum, while for lessmassive magnetic CP stars an angular momentum loss cannot be ruledout. Conclusions: .The mechanism that originates and sustains themagnetic field in the upper main sequence stars may be different in CPstars of different mass.
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Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars
This paper presents the catalogue and the method of determination ofaveraged quadratic effective magnetic fields < B_e > for 596 mainsequence and giant stars. The catalogue is based on measurements of thestellar effective (or mean longitudinal) magnetic field strengths B_e,which were compiled from the existing literature.We analysed the properties of 352 chemically peculiar A and B stars inthe catalogue, including Am, ApSi, He-weak, He-rich, HgMn, ApSrCrEu, andall ApSr type stars. We have found that the number distribution of allchemically peculiar (CP) stars vs. averaged magnetic field strength isdescribed by a decreasing exponential function. Relations of this typehold also for stars of all the analysed subclasses of chemicalpeculiarity. The exponential form of the above distribution function canbreak down below about 100 G, the latter value representingapproximately the resolution of our analysis for A type stars.Table A.1 and its references are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/407/631 and Tables 3 to 9are only available in electronic form at http://www.edpsciences.org
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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
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The HR-diagram from HIPPARCOS data. Absolute magnitudes and kinematics of BP - AP stars
The HR-diagram of about 1000 Bp - Ap stars in the solar neighbourhoodhas been constructed using astrometric data from Hipparcos satellite aswell as photometric and radial velocity data. The LM method\cite{luri95,luri96} allows the use of proper motion and radial velocitydata in addition to the trigonometric parallaxes to obtain luminositycalibrations and improved distances estimates. Six types of Bp - Apstars have been examined: He-rich, He-weak, HgMn, Si, Si+ and SrCrEu.Most Bp - Ap stars lie on the main sequence occupying the whole width ofit (about 2 mag), just like normal stars in the same range of spectraltypes. Their kinematic behaviour is typical of thin disk stars youngerthan about 1 Gyr. A few stars found to be high above the galactic planeor to have a high velocity are briefly discussed. Based on data from theESA Hipparcos astrometry satellite and photometric data collected in theGeneva system at ESO, La Silla (Chile) and at Jungfraujoch andGornergrat Observatories (Switzerland). Tables 3 and 4 are onlyavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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The ROSAT galactic plane survey: analysis of a low latitude sample area in Cygnus.
We present the analysis of the point source content of a low galacticlatitude region selected from the ROSAT all-sky survey. The test fieldis centered at l=90deg, b=0deg and has an area of 64.5deg^2^. A total of128 soft X-ray sources are detected above a maximum likelihood of 8.Catalogue searches and optical follow-up observations show that in thisdirection of the galactic plane, 85% of the sources brighter than 0.03PSPC cts/s are identified with active coronae. F-K type stars represent67%(+/-13%) of the stellar identifications and M type stars account for19%(+/-6%). A small but significant number of X-ray sources areassociated with A type stars on the basis of positional coincidence.These results together with those of similar optical campaignsdemonstrate that the soft X-ray population of the Milky Way is largelydominated by active stars. We show that the density and distribution influx and spectral type of the active coronae detected in X-rays areconsistent with the picture drawn from current stellar population modelsand age dependent X-ray luminosity functions. The modelling of thispopulation suggests that most of the stars detected by ROSAT in thisdirection are younger than 1Gyr. This opens the possibility to extractin a novel way large samples of young stars from the ROSAT all-skysurvey. The small number of unidentified sources at low X-ray flux putrather strong constraints on the hypothetical X-ray emission from oldneutron stars accreting from the interstellar medium. Our observationsclearly rule out models which assume no dynamical heating for thispopulation and a total number of N_ns_=10^9^ neutron stars in theGalaxy. If accretion on polar caps is the dominant mode then our upperlimit may imply N_ns_=~10^8^. Among the non coronal identifications arethree white dwarfs, a Seyfert 1 active nucleus, two early type stars andone cataclysmic variable. We also report the discovery of a Me + WDclose binary system with P_orb_=~12h.
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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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A new list of effective temperatures of chemically peculiar stars. II.
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The Magnetic Fields and another Parameters of the Chemically Peculiar Stars - Part One
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On the Effective Temperatures of Chemically Peculiar Stars
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The Investigation of the Mean Surface Fields of the Ap-Stars
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Evidence of decay of the magnetic fields of AP stars
Data obtained in the Geneva photometric system (Rufener, 1981) andappropriate calibrations of this system in terms of surface magneticfield and gravity are used to provide, on the basis of 708 field andcluster Ap stars, observational evidence that these stars undergo decayof their magnetic field on an evolutionary timescale. Justifications aregiven for the application of a photometric gravity calibration topeculiar stars. The dependence of the photometrically estimated surfacemagnetic field on gravity is found to differ markedly from availabletheoretical calculations. HgMn stars are found to show the same trend,strengthening the impression that they might be slightly magnetic.He-weak stars do not.
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Photometric properties of AP stars in the Geneva system
An examination of the properties in some photometric diagrams of morethan 600 Ap stars measured in the Geneva photometric system confirm thatthe Balmer discontinuity is smaller than for normal stars, along withthe link between a proposed peculiarity parameter and both rotationalvelocity and effective magnetic field. It is shown that the peculiarityparameter is sensitive to interstellar reddening, and it is foundthrough examination of the standard deviations for visual magnitudesthat cool CP 2 stars without Eu peculiarity have the greatestamplitudes. Rapid rotators have a mild peculiarity, while positivecorrelation exists for Si and SrCr stars.
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A search for stars with a strong magnetic field
The effective longitudinal magnetic field strength He on ninepeculiar stars with maximal values for their presumed surface field hasbeen measured on Zeeman spectrograms taken with the 6-m telescope. Fourof the stars do exhibit strong fields. The outstanding example is HD147010, whose peak value He = -4480 + or - 440 gauss placesit fifth among stars with the strongest fields known.
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Effective temperature of AP stars
To determine the effective temperature of a sample of 69 mostly cool Apstars, the intensity of the CaII K line was taken as a temperatureindicator. It is demonstrated quantitatively that the K line is normalin Ap stars. Effective temperatures deduced from the K line intensity,T(eff) CaII are lower than those generally admitted for Ap stars, whichis in agreement with theoretical results from specific models. T(eff)CaII are also in agreement with T(eff) deduced from ultravioletphotometric index Delta-m 2100 and with those deduced from (U-B) and(B-V) corrected of line blocking effects.
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Catalogue of photometric data related to surface magnetic fields for B-type stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...41..111C&db_key=AST
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A photoelectric parameter of the peculiarity of the AP stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...26...49H&db_key=AST
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Observations spectrographiques d'etoiles A a spectre particulier et a raies metalliques.
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Catalogue et bibliographie des étoiles A à spectre particulier - Deuxième supplément
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Riduzione degli errori sistematici nelle osservazioni meridiane di tempo e di longitudine
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Catalogue et bibliographie des étoiles A à spectre particulier Premier supplément
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Catalogue et bibliographie des étoiles A à spectre particulier
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Peculiar and Metallic-Line a - Stars in a Galactic Zone.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1959ApJ...129...88S&db_key=AST
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A Catalog of Magnetic Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958ApJS....3..141B&db_key=AST
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Mesures de vitesses radiales au spectrographe C de l'Observatoire de Haute Provence
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Caractères spectraux de quelques étoiles particulières
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Anomalous Spectra of Stars of Class a.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1949ApJ...110...67W&db_key=AST
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INHABITED SKY
