Contents
Images
Upload your image
DSS Images Other Images
Related articles
The Indo-US Library of Coudé Feed Stellar Spectra
We have obtained spectra for 1273 stars using the 0.9 m coudéfeed telescope at Kitt Peak National Observatory. This telescope feedsthe coudé spectrograph of the 2.1 m telescope. The spectra havebeen obtained with the no. 5 camera of the coudé spectrograph anda Loral 3K×1K CCD. Two gratings have been used to provide spectralcoverage from 3460 to 9464 Å, at a resolution of ~1 Å FWHMand at an original dispersion of 0.44 Å pixel-1. For885 stars we have complete spectra over the entire 3460 to 9464 Åwavelength region (neglecting small gaps of less than 50 Å), andpartial spectral coverage for the remaining stars. The 1273 stars havebeen selected to provide broad coverage of the atmospheric parametersTeff, logg, and [Fe/H], as well as spectral type. The goal ofthe project is to provide a comprehensive library of stellar spectra foruse in the automated classification of stellar and galaxy spectra and ingalaxy population synthesis. In this paper we discuss thecharacteristics of the spectral library, viz., details of theobservations, data reduction procedures, and selection of stars. We alsopresent a few illustrations of the quality and information available inthe spectra. The first version of the complete spectral library is nowpublicly available from the National Optical Astronomy Observatory(NOAO) via ftp and http.
| A Survey of Nearby Main-Sequence Stars for Submillimeter Emission
We searched for submillimeter emission around 10 Vega-type stars and oneHerbig Ae star with the four-color bolometer at 1300 μm and the 19channel bolometer array at 870 μm using the Heinrich Hertz Telescopeat the Submillimeter Telescope Observatory. All of our sources wereundetected at 870 μm. In the case of HD 131156, we have a 3 σdetection at 1300 μm. We report a flux of 6.25+/-1.88 mJy for the HD131156 disk and a corresponding dust mass of 2.4+/-0.7 lunar masses.However, we did not detect HD 131156 at 870 μm, so we are cautiousabout the 1300 μm detection. We performed follow-up infraredobservations of HD 131156 using MIRLIN at the Palomar 200 inchtelescope, which resolved both components of the binary. The data arephotospheric, implying that the system does not have a hot, inner dustcomponent. We report submillimeter upper limits on fluxes for theremaining systems.
| Time-resolved infrared spectroscopy of WZ Sge during superoutburst: Evidence for spiral waves in the accretion disc
Time-resolved J and K band spectra were obtained for WZ Sge four daysinto its 2001 superoutburst. These data represent the firsttime-resolved IR spectra obtained of any dwarf nova during asuperoutburst. The spectra show the usual broad emission lines due to Hand He I plus strong He II (1.163 mu m), the latter line beingessentially absent at minimum light. The J-band spectra contain complexline emission from C I, Fe I, Na I, and Ca I and show asymmetric H andHe line emission from the accretion disc. The K-band continuum revealsan increasing slope to the red as seen during minimum light. Dopplermaps produced from the IR spectra indicate the presence of asymmetricemission within the accretion flow, in agreement with the opticaldetection of prominent spiral arms present within the accretion disc.
| Automated spectroscopic abundances of A and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE
Using the method presented in Erspamer & North (\cite{erspamer},hereafter Paper I), detailed abundances of 140 stars are presented. Theuncertainties characteristic of this method are presented and discussed.In particular, we show that for a S/N ratio higher than 200, the methodis applicable to stars with a rotational velocity as high as 200 kms-1. There is no correlation between abundances and Vsin i,except a spurious one for Sr, Sc and Na which we explain by the smallnumber of lines of these elements combined with a locally biasedcontinuum. Metallic giants (Hauck \cite{hauck}) show larger abundancesthan normal giants for at least 8 elements: Al, Ca, Ti, Cr, Mn, Fe, Niand Ba. The anticorrelation for Na, Mg, Si, Ca, Fe and Ni with Vsin isuggested by Varenne & Monier (\cite{varenne99}) is not confirmed.The predictions of the Montréal models (e.g. Richard et al.\cite{richard01}) are not fulfilled in general. However, a correlationbetween left [(Fe)/(H)right ] and log g is found for stars of 1.8 to 2.0M_sun. Various possible causes are discussed, but the physical realityof this correlation seems inescapable.Based on observations collected at the 1.93 m telescope at theObservatoire de Haute-Provence (St-Michel l'Observatoire, France) andCORALIE.Based on observations collected at the Swiss 1.2 m Leonard Eulertelescopes at the European Southern Observatory (La Silla, Chile).Tables 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u.strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/1121
| The status of Galactic field λ Bootis stars in the post-Hipparcos era
The λ Bootis stars are Population I, late B- to early F-typestars, with moderate to extreme (up to a factor 100) surfaceunderabundances of most Fe-peak elements and solar abundances of lighterelements (C, N, O and S). To put constraints on the various existingtheories that try to explain these peculiar stars, we investigate theobservational properties of λ Bootis stars compared with areference sample of normal stars. Using various photometric systems andHipparcos data, we analyse the validity of standard photometriccalibrations, elemental abundances, and Galactic space motions. Therecrystallizes a clear picture of a homogeneous group of Population Iobjects found at all stages of their main-sequence evolution, with apeak at about 1 Gyr. No correlation of astrophysical parameters such asthe projected rotational velocities or elemental abundances with age isfound, suggesting that the a priori unknown mechanism, which createsλ Bootis stars, works continuously for late B- to early F-typestars in all stages of main-sequence evolution. Surprisingly, the sodiumabundances seem to indicate an interaction between the stars and theirlocal environment.
| Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i
This work is the second part of the set of measurements of v sin i forA-type stars, begun by Royer et al. (\cite{Ror_02a}). Spectra of 249 B8to F2-type stars brighter than V=7 have been collected at Observatoirede Haute-Provence (OHP). Fourier transforms of several line profiles inthe range 4200-4600 Å are used to derive v sin i from thefrequency of the first zero. Statistical analysis of the sampleindicates that measurement error mainly depends on v sin i and thisrelative error of the rotational velocity is found to be about 5% onaverage. The systematic shift with respect to standard values fromSlettebak et al. (\cite{Slk_75}), previously found in the first paper,is here confirmed. Comparisons with data from the literature agree withour findings: v sin i values from Slettebak et al. are underestimatedand the relation between both scales follows a linear law ensuremath vsin inew = 1.03 v sin iold+7.7. Finally, thesedata are combined with those from the previous paper (Royer et al.\cite{Ror_02a}), together with the catalogue of Abt & Morrell(\cite{AbtMol95}). The resulting sample includes some 2150 stars withhomogenized rotational velocities. Based on observations made atObservatoire de Haute Provence (CNRS), France. Tables \ref{results} and\ref{merging} are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/897
| Ages of A-Type Vega-like Stars from uvbyβ Photometry
We have estimated the ages of a sample of A-type Vega-like stars byusing Strömgren uvbyβ photometric data and theoreticalevolutionary tracks. We find that 13% of these A stars have beenreported as Vega-like stars in the literature and that the ages of thissubset run the gamut from very young (50 Myr) to old (1 Gyr), with noobvious age difference compared to those of field A stars. We clearlyshow that the fractional IR luminosity decreases with the ages ofVega-like stars.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable 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/qcar?J/A+A/367/521
| Research Note Hipparcos photometry: The least variable stars
The data known as the Hipparcos Photometry obtained with the Hipparcossatellite have been investigated to find those stars which are leastvariable. Such stars are excellent candidates to serve as standards forphotometric systems. Their spectral types suggest in which parts of theHR diagrams stars are most constant. In some cases these values stronglyindicate that previous ground based studies claiming photometricvariability are incorrect or that the level of stellar activity haschanged. Table 2 is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/367/297
| The proper motions of fundamental stars. I. 1535 stars from the Basic FK5
A direct combination of the positions given in the HIPPARCOS cataloguewith astrometric ground-based catalogues having epochs later than 1939allows us to obtain new proper motions for the 1535 stars of the BasicFK5. The results are presented as the catalogue Proper Motions ofFundamental Stars (PMFS), Part I. The median precision of the propermotions is 0.5 mas/year for mu alpha cos delta and 0.7mas/year for mu delta . The non-linear motions of thephotocentres of a few hundred astrometric binaries are separated intotheir linear and elliptic motions. Since the PMFS proper motions do notinclude the information given by the proper motions from othercatalogues (HIPPARCOS, FK5, FK6, etc.) this catalogue can be used as anindependent source of the proper motions of the fundamental stars.Catalogue (Table 3) is only available at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strastg.fr/cgi-bin/qcat?J/A+A/365/222
| Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over more than twocenturies and summarized in the FK5. Part I of the FK6 (abbreviatedFK6(I)) contains 878 basic fundamental stars with direct solutions. Suchdirect solutions are appropriate for single stars or for objects whichcan be treated like single stars. From the 878 stars in Part I, we haveselected 340 objects as "astrometrically excellent stars", since theirinstantaneous proper motions and mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,199 of the stars in Part I are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives in addition to the SI mode the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(I) proper motion in the single-star mode is 0.35 mas/year. This isabout a factor of two better than the typical HIPPARCOS errors for thesestars of 0.67 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(I) proper motions have atypical mean error of 0.50 mas/year, which is by a factor of more than 4better than the corresponding error for the HIPPARCOS values of 2.21mas/year (cosmic errors included).
| Systematic Errors in the FK5 Catalog as Derived from CCD Observations in the Extragalactic Reference Frame.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114..850S&db_key=AST
| ICCD speckle observations of binary stars: Measurements during 1994-1995
We present speckle observations of nineteen double stars and the triplestar 2 Cam. Angular separations, absolute position angles and relativephotometry result from these observations. The angular separation isderived from the power spectrum. The position angle and the relativephotometry are determined by two recent techniques: thecross-correlation between the speckle images and their square, and theratios of twofold probability density functions of the images. Based onobservations made at 2m Telescope Bernard Lyot, Pic du Midi, France.
| The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJS...99..135A&db_key=AST
| 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.
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
| The second Quito astrolabe catalogue
The paper contains 515 individual corrections {DELTA}α and 235corrections {DELTA}δ to FK5 and FK5Supp. stars and 50 correctionsto their proper motions computed from observations made with theclassical Danjon astrolabe OPL-13 at Quito Astronomical Observatory ofEcuador National Polytechnical School during a period from 1964 to 1983.These corrections cover the declination zone from -30deg to +30deg. Meanprobable errors of catalogue positions are 0.047" in αcosδand 0.054" in δ. The systematic trends of the catalogue{DELTA}αalpha_cosδ,{DELTA}αdelta_cosδ,{DELTA}δalpha_, {DELTA}δdelta_ arepresented for the observed zone.
| Astronomical computing.
Not Available
| Corrections to the right ascension to be applied to the apparent places of 1217 stars given in "The Chinese Astronomical Almanach" for the year 1984 to 1992.
Not Available
| SAO stars with infrared excess in the IRAS Point Source Catalog
We have undertaken a search for SAO stars with infrared excess in theIRAS Point Source Catalog. In contrast to previous searches, the entireIRAS (12)-(25)-(60) color-color diagram was used. This selection yieldeda sample of 462 stars, of which a significant number are stars withcircumstellar material. The stars selected can be identified aspre-main-sequence stars, Be stars, protoplanetary systems, post-AGBstars, etc. A number of objects are (visual) binary stars.Characteristic temperatures and IR excesses are calculated and theirrelations to spectral type are investigated.
| Santiago Fundamental Catalogue - A catalogue of 1105 FK5 stars (equinox J2000.0)
The positions in right ascension and declination of 1105 FK5 stars,observed with a Meridian Circle during the period 1979 to 1991, aregiven. The average mean square error of a position, for the wholecatalog, is +/- 0.009 s in right ascension and +/- 0.10 arcsec indeclination. The mean epoch of the catalog is 1983.148.
| An optical search for Beta Pictoris-like disks around nearby stars
A coronagraphic survey of more than one hundred stars has been carriedout in a search at optical wavelengths for circumstellar materialsimilar to that found in the Beta Pictoris disk. The survey stars wereprimarily dwarfs in the spectral range A to K and most were closer than100 pc. No evidence of circumstellar material was found around any ofthe stars, suggesting that Beta Pictoris is an abnormal object,surrounded by an unusually large amount of optically scatteringmaterial.
| The correction in right ascension of 508 stars determinated with PMO photoelectric transit instrument.
Not Available
| The stellar temperature scale for stars of spectral types from O8 to F6 and the standard deviation of the MK spectral classification
Empirical effective temperature of 211 early-type stars found in aprevious investigation (Kontizas and Theodossiou, 1980; Theodossiou,1985) are combined with the effective temperatures of 313 early-typestars from the literature. From these effective temperatures of a totalnumber of 524 early-type stars of spectral types from O8 to F6 a newstellar temperature scale is developed along with the standard deviationof the MK spectral classification.
| An IRAS survey of main sequence B, A, and F stars
Results are presented of an IRAS survey of main-sequence B, A, and Fstars, based on three primary sources as a data base: theBernacca-Perinotto Catalog of Stellar Rotational Velocities, theMichigan Spectral Catalog, and the Bright Star Catalog. The stars in thedata base are divided into four categories: (1) main-sequence singlestars, (2) main-sequence close binary stars, (3) spectrally peculiarstars such as Am, Ap, Fm, and Fp stars, and (4) subgiants. It is foundthat about 20 percent of main-sequence single stars show an IR colorexcess in at least one of the 12, 25, or 60 micron IRAS bands, while theother three groups do not show any statistically significant percentageof IR color excess stars. It is also found that stars with large (v sini) values are more likely to show color excesses at IRAS wavelengthsthan stars with small (v sin i) values.
| Santiago declination catalogue. II - A declination catalogue of 493 FK5 stars (equinox J2000.0)
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991A&AS...90..109C&db_key=AST
| Absolute magnitudes of B emission line stars - Correlation between the luminosity excess and the effective temperature
A new determination of the visual absolute magnitude of Be stars iscarried out. For this, a new calibration of visual absolute magnitudesof B stars of luminosity classes, V, IV, and III is first obtained froma sample of 215 stars. The absolute luminosity excess in the visual isdetermined for a sample of 49 Be stars. It is found that this excess iscorrelated with the effective temperature of the underlying stars. Awell defined correlation between this excess and the emission in thefirst two Balmer lines is established. From these results, using asimple model of circumstellar envelope, it is inferred that the zones ofthe circumstellar envelope contributing to the emission in the continuumand in the lines have to be rather small. It is also deduced that theemission measure of the envelope is correlated with the temperature ofthe central star and that the irregular photometric variations of Bestars are an envelope-opacity phenomenon.
| Physical data of the fundamental stars.
Not Available
| Three micron spectroscopy of low-mass pre-main-sequence stars
Low-resolution spectra were obtained of 16 premain-sequence stars, andice-band features are detected in young T Tauri stars (TTSs) and inlow-mass protostars. The TTSs have an ice band optical depth tau(ice) of0.1-0.4. The tau(ice) for objects in the Taurus dark cloud decreasesprogressively from protostars to TTSs. The apparent color temperaturesof the continuum spectra are 800-1200 K for protostars and 1100-1500 Kfor TTSs. The color temperatures of the continuum increase to 1200-2000Kafter correcting the protostar spectra for foreground extinction. Thiscommon temperature range in both young TTSs and protostars suggests thatthe inner boundary of the circumstellar disk is determined by thesublimation of refractory grains.
| Stellar integrated fluxes in the wavelength range 380 NM - 900 NM derived from Johnson 13-colour photometry
Petford et al. (1988) have reported measured integrated fluxes for 216stars with a wide spread of spectral type and luminosity, and mentionedthat a cubic-spline integration over the relevant Johnson 13-colormagnitudes, converted to fluxes using Johnson's calibration, is inexcellent agreement with those measurements. In this paper a list of thefluxes derived in this way, corrected for a small dependence on B-V, isgiven for all the 1215 stars in Johnson's 1975 catalog with completeentries.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Aquila |
| Right ascension: | 20h14m16.60s |
| Declination: | +15°11'51.0" |
| Apparent magnitude: | 4.95 |
| Distance: | 47.081 parsecs |
| Proper motion RA: | 55.6 |
| Proper motion Dec: | 58.6 |
| B-T magnitude: | 5.028 |
| V-T magnitude: | 4.954 |
Catalogs and designations:
|
