Spectroscopy of IRAS 02091+6333
We present a detailed spectroscopic investigation, spanning fourwinters, of the asymptotic giant branch star IRAS 02091+6333. Zijlstra& Weinberger (2002) found a giant wall of dust around this star andmodelled this unique phenomenon. However their work suffered from thequality of the optical investigations of the central object. They coulduse only a single quick look spectrum and the original TYCHO Bt and Vtmagnitudes to estimate the spectral type and the interstellar extinctiontowards the target. Thus we obtained spectra and photometry at theInnsbruck 60cm telescope (Kimeswenger 2001) of this unique object forseveral years to derive an accurate spectral type and the foregroundextinction. This allowed us to determine more precisely the distance tothe target which is important for the modelling of the dust shell foundon IRAS images. Zijlstra & Weinberger (2002) outline such shells forvarious types of objects at late stages of their evolution. Their focuswas especially on a swept up shell with a void in the interstellarmatter around the target. This is crucial for both, the "Swiss cheese"like structure of the interstellar material and for the hydrodynamicevolution of the planetary nebula built after the current evolutionarystage.The measurements presented here suggest a weak irregular photometricvariability of the target, while there is no evidence of a spectroscopicvariability over the last four years.
|
Wing Near-Infrared, TiO-Band, and V-Band Photometry of Chromospherically Active Star λ Andromedae
As a pilot program, Wing near-IR, TiO-band, and V-band photometry isbeing conducted of the RS Canum Venaticorum type, chromosphericallyactive, G8 IV-III star λ Andromedae. The objective is toinvestigate a possible relationship between variation of the ~54 dayrotationally starspot modulated visual light curve and TiO absorptionstrength. The TiO (γ,0,0) absorption band strength at λ=719nm is very sensitive to temperature for cool stars and manifests itselfin cooler starspot regions (T<=4000 K). TiO photometry has anadvantage over conventional photometry in that it provides unambiguousmeasures of the fractional cool starspot coverage. In addition, as thestars rotate, the variation in the TiO index yields information aboutthe longitudinal distribution of the starspots. Importantly, combiningthe TiO photometry with the V-band and near-IR light curves allows thediscrimination of white-light faculae (=hot spot) and cool starspotcontributions. Initial results of this study indicate that the observedV-band and near-IR continua light variations found for λ Andprimarily arise from bright spot (plage) features rather than darkstarspots as is usually assumed. This is in contrast to current theoriesthat the visual light variation is solely due to dark spots. Modelsusing both bright and dark spot features have been developed and arebeing used to fit the light and TiO-index curves. The models account forcool/hot spot characteristics such as projected filling factor andtemperature. The long-term variation of V light and TiO index have beeninvestigated to search for any activity cycles.
|
Optical spectroscopy of IRAS 02091+6333
We present a detailed spectroscopic investigation, spanning fourwinters, of the asymptotic giant branch (AGB) star IRAS 02091+6333.Zijlstra & Weinberger (\cite{ZW}) found a giant wall of dust aroundthis star and modelled this unique phenomenon. However their worksuffered from the quality of the optical investigations of the centralobject. Our spectroscopic investigation allowed us to define thespectral type and the interstellar foreground extinction more precisely.Accurate multi band photometry was carried out. This provides us withthe possibility to derive the physical parameters of the system. Themeasurements presented here suggest a weak irregular photometricvariability of the target, while there is no evidence of a spectroscopicvariability over the last four years.Based on observations at the Innsbruck 60-cm telescope and the FlemishMercator telescope on Roque de los Muchachos, Spain.
|
Hipparcos red stars in the HpV_T2 and V I_C systems
For Hipparcos M, S, and C spectral type stars, we provide calibratedinstantaneous (epoch) Cousins V - I color indices using newly derivedHpV_T2 photometry. Three new sets of ground-based Cousins V I data havebeen obtained for more than 170 carbon and red M giants. These datasetsin combination with the published sources of V I photometry served toobtain the calibration curves linking Hipparcos/Tycho Hp-V_T2 with theCousins V - I index. In total, 321 carbon stars and 4464 M- and S-typestars have new V - I indices. The standard error of the mean V - I isabout 0.1 mag or better down to Hp~9 although it deteriorates rapidly atfainter magnitudes. These V - I indices can be used to verify thepublished Hipparcos V - I color indices. Thus, we have identified ahandful of new cases where, instead of the real target, a random fieldstar has been observed. A considerable fraction of the DMSA/C and DMSA/Vsolutions for red stars appear not to be warranted. Most likely suchspurious solutions may originate from usage of a heavily biased color inthe astrometric processing.Based on observations from the Hipparcos astrometric satellite operatedby the European Space Agency (ESA 1997).}\fnmsep\thanks{Table 7 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/397/997
|
Long period variable stars: galactic populations and infrared luminosity calibrations
In this paper HIPPARCOS astrometric and kinematic data are used tocalibrate both infrared luminosities and kinematical parameters of LongPeriod Variable stars (LPVs). Individual absolute K and IRAS 12 and 25luminosities of 800 LPVs are determined and made available in electronicform. The estimated mean kinematics is analyzed in terms of galacticpopulations. LPVs are found to belong to galactic populations rangingfrom the thin disk to the extended disk. An age range and a lower limitof the initial mass is given for stars of each population. A differenceof 1.3 mag in K for the upper limit of the Asymptotic Giant Branch isfound between the disk and old disk galactic populations, confirming itsdependence on the mass in the main sequence. LPVs with a thin envelopeare distinguished using the estimated mean IRAS luminosities. The levelof attraction (in the classification sense) of each group for the usualclassifying parameters of LPVs (variability and spectral types) isexamined. Table 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/374/968 or via ASTRIDdatabase (http://astrid.graal.univ-montp2.fr).
|
Spectral Irradiance Calibration in the Infrared. IX. Calibrated Stellar Spectra Using DIRBE Radiometry
The absolute calibration of the COBE/DIRBE data in the range 1-25 μmis examined through the in-band fluxes of DIRBE's own set ofpoint-source calibration objects. Using the values of DIRBE fluxesexpected for Sirius and for 10 of our published set of absolutelycalibrated K and M giants that are in common with DIRBE's owncalibration network, I find consistency with the project's formal basis,namely, our published calibrated spectrum of Sirius. This consistencymeans that one can use the DIRBE radiometry to construct absolutelycalibrated ``stellar templates'' (i.e., continuous calibrated spectrafrom 1 to 35 μm) on the assumption that the intrinsic stellarspectrum of a star of given spectral class matches the intrinsicspectrum for the star of the same spectral class among the set of K andM giants, the spectrum of which has been absolutely defined. Thistechnique is validated using a set of early M giants withwell-characterized ground-based photometry and confirmed with IRASlow-resolution spectra.
|
Classification and Identification of IRAS Sources with Low-Resolution Spectra
IRAS low-resolution spectra were extracted for 11,224 IRAS sources.These spectra were classified into astrophysical classes, based on thepresence of emission and absorption features and on the shape of thecontinuum. Counterparts of these IRAS sources in existing optical andinfrared catalogs are identified, and their optical spectral types arelisted if they are known. The correlations between thephotospheric/optical and circumstellar/infrared classification arediscussed.
|
Water Masers Associated with Circumstellar Shells
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJS..106..579B&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.
|
On the spectra and photometry of M-giant stars
From a sample of 97 very bright M-giant stars in the Solarneighbourhood, high-quality "intrinsic" spectra in the spectral range380 <~ λ[nm] <~ 900 for all M-spectral subtypes of the Caseand MK classification systems are obtained. The results are fitted tophotospheric synthetic spectra in the range 99 <~ λ [nm]<=12500 in order to infer the corresponding continua. The syntheticspectra are also compared to the intrinsic spectra. The effectivetemperatures are derived and mathematical spectral classificationcriteria are found. The (UB)_j_(VRI)_c_(JHKLM)_ESO_ photometric data ofthe sample are also given. The data are available on the StrasbourgAstronomical Data Centre (CDS).
|
S stars: infrared colors, technetium, and binarity
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&A...271..463J&db_key=AST
|
Asymptotic giant branch stars near the sun
Available red and near-infrared photometry and apparent motions of M, S,and C asymptotic giant branch (AGB) stars in the Bright Star Catalogueare tabulated and discussed. It is shown that the red and near infraredindices normally used for late-type stars are interchangeable except forcarbon stars. The M-type giants are variable with visual amplitudegreater than 0.05 mag. The reddening-free parameter m2 from Genevaphotometry is essentially a temperature parameter for M giants, whilethe reddening-free parameter d is a sensitive detector of blue stellarcompanions. The space density of AGB stars near the sun decreases by afactor of 35 in a temperature range 3800 to 3400 K. Two of the S starsnear the sun were found to have nearly equal space motions and may becomembers of the Arcturus group.
|
Statistical characteristics of the ten-micron silicate emission in M-type stars
The statistical characteristics of 10 micron silicate emission wereexamined for 1427 M-type stars in the catalog of the Two-Micron SkySurvey using the low-resolution spectra obtained by IRAS. Correlationswere examined of 10 micron silicate emission with the spectralclassification in the visual wavelength region, with near-infrared colorI - K, with a variability type, and with the period of variation. It wasfound that supergiants show silicate emission more frequently than dogiants. Silicate emission was found in stars of all three variabilitytypes: irregular, semiregular, and Mira variables. The proportion ofstars with silicate emission was found to be larger for Mira variables.Most of the Mira variables with periods of variation longer than about450 d were found to show silicate emission.
|
Einstein Observatory magnitude-limited X-ray survey of late-type giant and supergiant stars
Results are presented of an extensive X-ray survey of 380 giant andsupergiant stars of spectral types from F to M, carried out with theEinstein Observatory. It was found that the observed F giants orsubgiants (slightly evolved stars with a mass M less than about 2 solarmasses) are X-ray emitters at the same level of main-sequence stars ofsimilar spectral type. The G giants show a range of emissions more than3 orders of magnitude wide; some single G giants exist with X-rayluminosities comparable to RS CVn systems, while some nearby large Ggiants have upper limits on the X-ray emission below typical solarvalues. The K giants have an observed X-ray emission level significantlylower than F and F giants. None of the 29 M giants were detected, exceptfor one spectroscopic binary.
|
The cool components of symbiotic stars. II - Infrared photometry
This paper reports IR photometry for a sample of symbiotic binaries andK-M comparison stars. Measured CO absorption-band strengths of the coolcomponents in symbiotic stars generally are comparable to those ofsingle red giant and bright giant stars, but it is difficult todetermine the luminosity classes of these objects from their photometricCO indices. The 12-micron excesses observed in symbiotics require theircool components to lose mass more rapidly than do single red giantstars. Thus, mass-loss rates derived for red giants in close binarysystems may not be accurate estimates for mass loss in single redgiants.
|
Additional late-type stars with technetium
The results of a survey of 279 late-type giants and supergiants for thespectral lines of the radioactive element technetium (Tc I) at 4297,4262, and 4238 A are presented. The following conclusions are reached:(1) the presence of Tc correlates very strongly with the existence oflight variability; (2) evolutionary MS stars show Tc and spectroscopicMS stars do not show Tc; (3) single S stars show Tc; (4) SC stars showTc; (5) about 75 percent of the C stars show Tc; and (6) Ba II stars donot show Tc. The findings are compatible with predictions from stellarevolution theory.
|
The cool components of symbiotic stars. I - Optical spectral types
An analysis of prominent absorption features on red spectra of symbioticstars is presented. The depths of TiO and VO bands appear to becorrelated with the brightness of the system; this behavior is probablythe result of the secondary star heating the outer atmosphere of thecool giant. New spectral types and luminosity classes for the coolcomponents of symbiotics are derived, and these classifications suggesta division into semidetached systems and detached systems. Mass-lossrates for detached symbiotics, which do not contain Mira variables,remain higher than those estimated for single red giants of the samespectral type, suggesting that the presence of a binary companionenhances mass loss in these objects.
|
IRAS catalogues and atlases - Atlas of low-resolution spectra
Plots of all 5425 spectra in the IRAS catalogue of low-resolutionspectra are presented. The catalogue contains the average spectra ofmost IRAS poiont sources with 12 micron flux densities above 10 Jy.
|
The brightest high-latitude 12-micron IRAS sources
The Infrared Astronomical Satellite (IRAS) Point Source catalog wassearched for sources brighter than 28 Jy (0 mag) at 12 microns withabsolute galactic latitude greater than 30 deg excluding the LargeMagellanic Cloud. The search resulted in 269 sources, two of which arethe galaxies NGC 1068 and M82. The remaining 267 sources are identifiedwith, or have infrared color indices consistent with late-type starssome of which show evidence of circumstellar dust shells. Seven sourcesare previously uncataloged stars. K and M stars without circumstellardust shells, M stars with circumstellar dust shells, and carbon starsoccupy well-defined regions of infrared color-color diagrams.
|
The circumstellar envelopes and chromospheres of cool giants and supergiants
A survey of the circumstellar (CS) envelopes of cool giants andsupergiants shows no correlation between the quantities of CS gas anddust, indicating that radiation pressure on dust grains is not theprincipal mechanism of mass loss. The observed quantity of dust is notsufficient to drive the observed mass loss. Stars with high dust-to-gasratios were also seen to show a high proportion of neutral to ionizedgas and a lack of Ca II H and K emission, and in many cases, Balmeremission, and/or molecular masing. It is argued that shock waves may belinked to dust formation. Mass loss rates were derived for the programstars and found to correlate with K4 absorption width, indicating thatthe mass loss mechanism may be coupled to turbulence.
|
Uvby-beta photometry of visual double stars - Absolute magnitudes of intrinsically bright stars
Individual absolute visual magnitudes M(v) are derived for intrinsicallybright stars and evolved stars. The results are collected for 106objects believed to be members of binary systems. uvby-beta photometrywas empirically calibrated in terms of M(v) for main sequence stars andphotoelectrically determined apparent magnitudes. The derived M(v)values are not significantly different from those stated in the Wilsoncatalogue (1976). Binary systems with main sequence primaries andsecondary components off the main sequence were also investigated.Several systems in which at least one component may be in the pre-mainsequence contraction stage are pointed out. A wide variety of commentsand derived data are given individually for 136 double stars, includingmetallicities, distance moduli, and masses.
|
Photoelectric Observations of Variable Stars of Late Spectral Types
Not Available
|
V-R Colours of Red Variable Stars
Not Available
|
Kinematical and orbital properties for selected southern high-velocity stars
Using the model of the Galaxy presented by Eggen, Lynden-Bell, andSandage (1962), plane galactic orbits have been calculated for severalsouthern high-velocity stars which possess parallax, proper motion, andradial velocity data. Extensive lists of both raw and computed data forthese stars are included. Published values of U-B and B-V for some ofthese stars were used in plots of each of the orbital parameters versusU-B, B-V, or the ultraviolet excess. Also, a comparison is made betweenthe H-R diagrams for the southern high-velocity star group and that ofM3, a globular cluster, and again for M67, an old open cluster. Thehigh-velocity star group is found to resemble an old open cluster morethan a globular cluster.
|
Broad-band 20-mu photometry of 50 stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..764S&db_key=AST
|
Photoelectric multiband photometry of M giants and supergiants in the blue-visual spectral region
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&AS...22..171H&db_key=AST
|
Four-color photometry of late-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79.1424O&db_key=AST
|
Spectroscopic observations of M giant stars at the south galactic pole.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973MNRAS.162...11C&db_key=AST
|
59th Name-List of Variable Stars
Not Available
|
INHABITED SKY
