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The mass-loss rates of red supergiants and the de Jager prescription
Mass loss of red supergiants (RSG) is important for the evolution ofmassive stars, but is not fully explained. Several empiricalprescriptions have been proposed, trying to express the mass-loss rate(dot M) as a function of fundamental stellar parameters (mass,luminosity, effective temperature). Our goal is to test whether the deJager et al. (1988, A&AS, 72, 259) prescription, which is used insome stellar evolution models, is still valid in view of more recentmass-loss determinations. By considering 40 Galactic RSGs with aninfrared excess and an IRAS 60-?m flux larger than 2 Jy, and assuminga gas-to-dust mass ratio of 200, we find that the de Jager rate agreeswithin a factor 4 with most dot M estimates based on the 60-?msignal. It also agrees with six of the only eight Galactic RSGs forwhich dot M can be measured more directly through observations of thecircumstellar gas. The two objects that do not follow the de Jagerprescription (by an order of magnitude) are ? Cep and NML Cyg. Wealso considered the RSGs of the Magellanic Clouds. Thanks to the resultsof previous research, we find that the RSGs of the Small MagellanicCloud have mass-loss rates consistent with the de Jager rate scaled by(Z/Z&sun;)?, where Z is the metallicity and? is 0.7. The situation is less clear for the RSGs of the LargeMagellanic Cloud. In particular, for L > 1.6 × 105L&sun;, one finds numerous RSGs (except WOH-G64) with dot Msignificantly smaller than the de Jager rate and indicating that dot Mwould no longer increase with L. Before this odd situation is confirmedthrough further analyses of LMC RSGs, we suggest to keep the de Jagerprescription unchanged at solar metallicity in the stellar evolutionarymodels and to apply a (Z/Z&sun;)0.7 dependence.Appendices are only available in electronic form at http://www.aanda.org
| AKARI's infrared view on nearby stars. Using AKARI infrared camera all-sky survey, 2MASS, and Hipparcos catalogs
Context. The AKARI, a Japanese infrared space mission, has performed anAll-Sky Survey in six infrared-bands from 9 to 180 ?m with higherspatial resolutions and better sensitivities than IRAS. Aims: Weinvestigate the mid-infrared (9 and 18 ?m) point source catalog (PSC)obtained with the infrared camera (IRC) onboard AKARI, in order tounderstand the infrared nature of the known objects and to identifypreviously unknown objects. Methods: Color-color diagramsand a color-magnitude diagram were plotted with the AKARI-IRC PSCand other available all-sky survey catalogs. We combined the Hipparcosastrometric catalog and the 2MASS all-sky survey catalog with theAKARI-IRC PSC. We furthermore searched literature and SIMBADastronomical database for object types, spectral types, and luminosityclasses. We identified the locations of representative stars and objectson the color-magnitude and color-color diagram schemes. Theproperties of unclassified sources can be inferred from their locationson these diagrams. Results: We found that the (B-V) vs.(V-S9W) color-color diagram is useful for identifying thestars with infrared excess emerged from circumstellar envelopes ordisks. Be stars with infrared excess are separated well from other typesof stars in this diagram. Whereas (J-L18W) vs. (S9W-L18W)diagram is a powerful tool for classifying several object types.Carbon-rich asymptotic giant branch (AGB) stars and OH/IR stars formdistinct sequences in this color-color diagram. Young stellarobjects (YSOs), pre-main sequence (PMS) stars, post-AGB stars, andplanetary nebulae (PNe) have the largest mid-infrared color excess andcan be identified in the infrared catalog. Finally, we plot the L18W vs.(S9W-L18W) color-magnitude diagram, using the AKARI data togetherwith Hipparcos parallaxes. This diagram can be used to identify low-massYSOs and AGB stars. We found that this diagram is comparable to the [24]vs. ([8.0]-[24]) diagram of Large Magellanic Cloud sources usingthe Spitzer Space Telescope data. Our understanding of Galactic objectswill be used to interpret color-magnitude diagram of stellar populationsin the nearby galaxies that Spitzer Space Telescope observed. Conclusions: Our study of the AKARI color-color andcolor-magnitude diagrams will be used to explore properties ofunknown objects in the future. In addition, our analysis highlights afuture key project to understand stellar evolution with a circumstellarenvelope, once the forthcoming astronometrical data with GAIA areavailable.Catalog (full Tables 3 and 4) 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/514/A2
| The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
We present a 0.8-5 μm spectral library of 210 cool stars observed ata resolving power of R ≡ λ/Δλ ~ 2000 with themedium-resolution infrared spectrograph, SpeX, at the 3.0 m NASAInfrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. The stars havewell-established MK spectral classifications and are mostly restrictedto near-solar metallicities. The sample not only contains the F, G, K,and M spectral types with luminosity classes between I and V, but alsoincludes some AGB, carbon, and S stars. In contrast to some otherspectral libraries, the continuum shape of the spectra is measured andpreserved in the data reduction process. The spectra are absolutely fluxcalibrated using the Two Micron All Sky Survey photometry. Potentialuses of the library include studying the physics of cool stars,classifying and studying embedded young clusters and optically obscuredregions of the Galaxy, evolutionary population synthesis to studyunresolved stellar populations in optically obscured regions of galaxiesand synthetic photometry. The library is available in digital form fromthe IRTF Web site.
| Red giants in open clusters. XIV. Mean radial velocities for 1309 stars and 166 open clusters
Context: Radial velocities have proved to be an efficient method formembership determination if there are at least 2 or 3 red giants in acluster. They are necessary for galactic studies, but are still missingfor many open clusters. Aims: We present the final catalogues of along-term observing programme performed with the two coravelspectrovelocimeters for red giants in open clusters. The main aims wereto detect spectroscopic binaries and determine their orbital parameters,determine the membership, and compute mean velocities for the stars andopen clusters. Methods: We computed weighted mean radial velocities for1309 stars from 10 517 individual observations, including the systemicradial velocities from spectroscopic orbits and for cepheids. Results:The final results are contained in three catalogues collecting 10 517individual radial velocities, mean radial velocities for 1309 redgiants, and mean radial velocities for 166 open clusters among whichthere are 57 new determinations. We identified 891 members and 418non-members. We discovered a total of 288 spectroscopic binaries, amongwhich 57 are classified as non-members. In addition 27 stars were judgedto be variable in radial velocities and they are all red supergiants. Conclusions: The present material, combined with recent absolute propermotions, will permit various investigation of the galactic distributionand space motions of a large sample of open clusters. However, thedistance estimates still remain the weakest part of the necessary data.This paper is the last one in this series devoted to the study of redgiants in open clusters based on radial velocities obtained with thecoravel instruments.Based on observations collected at the Haute-Provence Observatory(France) and on observations collected with the Danish 1.54-m telescopesat the European Southern Observatory, La Silla, Chile. Full Tables [seefull textsee full textsee full textsee full textsee full text] to [seefull textsee full textsee full textsee full textsee full text] are onlyavailable and Tables [see full textsee full textsee full textsee fulltextsee full text] and [see full textsee full textsee full textsee fulltextsee full text] are also 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/485/303
| Further observations of Hipparcos red stars and standards for UBV(RI)C photometry
We present homogeneous and standardized UBV(RI)C JHKphotometry for over 100 M stars selected from an earlier paper on thebasis of apparent photometric constancy. L photometry has been obtainedfor stars brighter than about L = 6. Most of the stars have asubstantial number of UBV(RI)C observations and, it is hoped,will prove useful as red supplementary standards. Additionally, we listJHK photometry for nearly 300 Hipparcos red stars not selected asstandards, as well as L photometry for the brightest stars.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not As Cool As We Thought
We use moderate-resolution optical spectrophotometry and the new MARCSstellar atmosphere models to determine the effective temperatures of 74Galactic red supergiants (RSGs). The stars are mostly members of OBassociations or clusters with known distances, allowing a criticalcomparison with modern stellar evolutionary tracks. We find we canachieve excellent matches between the observations and the reddenedmodel fluxes and molecular transitions, although the atomic lines Ca Iλ4226 and Ca II H and K are found to be unrealistically strong inthe models. Our new effective temperature scale is significantly warmerthan those in the literature, with the differences amounting to 400 Kfor the latest type M supergiants (i.e., M5 I). We show that the newlyderived temperatures and bolometric corrections give much betteragreement with stellar evolutionary tracks. This agreement provides acompletely independent verification of our new temperature scale. Thecombination of effective temperature and bolometric luminosities allowsus to calculate stellar radii; the coolest and most luminous stars (KWSgr, Case 75, KY Cyg, HD 206936=μ Cep) have radii of roughly 1500Rsolar (7 AU), in excellent accordance with the largeststellar radii predicted from current evolutionary theory, althoughsmaller than that found by others for the binary VV Cep and for thepeculiar star VY CMa. We find that similar results are obtained for theeffective temperatures and bolometric luminosities using only thedereddened V-K colors, providing a powerful demonstration of theself-consistency of the MARCS models.
| 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
| UBV(RI)C photometry of Hipparcos red stars
We present homogeneous and standardized UBV(RI)C photometryfor nearly 550 M stars selected from the Hipparcos satellite data baseusing the following selection criteria: lack of obvious variability (noHipparcos variability flag); δ<+10°(V-I)>1.7 and Vmagnitude fainter than about 7.6. Comparisons are made between thecurrent photometry, other ground-based data sets and Hipparcosphotometry. We use linear discriminant analysis to determine aluminosity segregation criterion for late-type stars, and principalcomponent analysis to study the statistical structure of the colourindices and to calibrate absolute magnitude in terms of (V-I) for thedwarf stars. Various methods are used to determine the mean absolutemagnitude of the giant stars. We find 10 dwarf stars, apparentlypreviously unrecognized (prior to Hipparcos) as being within 25pc,including five within 20pc.
| Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Observational investigation of mass loss of M supergiants
We present the analysis of infrared photometry and millimeterspectroscopy of a sample of 74 late-type supergiants. These observationsare particularly suitable to study the mass loss and the circumstellarenvelopes of evolved massive stars. In particular, we quantify thecircumstellar infrared excess, the relation of mass loss with stellarproperties, using the K-[12] colour index as mass-loss indicator. We donot find any clear correlation between mass loss rate and luminosity. Wealso show that the K-band magnitude is a simple luminosity indicator,because of the relative constancy of the K-band bolometric correction.Based on observations collected at the European Southern Observatory, LaSilla, Chile within program ESO 54.E-0914, and on observations collectedwith the IRAM 30m telescope. Tables A1 to A3 are only 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
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| 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.
| An Infrared Color-Magnitude Relationship
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.2910H&db_key=AST
| Identification of 106 new infrared carbon stars in the IRAS Point Source Catalog - Near-infrared photometry and their space distribution in the galaxy
A method based solely on IR colors - the combination of near-IR and IRAScolors - is used to identify 106 new IR carbon stars (IRCS). It is shownthat the proportion of IRCS in a region of the IRAS two-color diagrampreviously thought to contain the largest concentration of such stars isnot as large as expected for the faintest objects. A local spatialnumber density of about 12 IRCS/sq kpc is estimated. It is shown to beuniform within 5 to 11 kpc from the galactic center. The local ratio ofIRCS to optical carbon stars is found to be about 35 percent. A totalrestitution rate of about 10 to the -4 solar masses/yr/sq kpc isderived. The efficiency of the combination of near and mid-IR photometryfor the study of AGB stars is confirmed.
| The Perkins catalog of revised MK types for the cooler stars
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
| A list of MK standard stars
Not Available
| Infrared circumstellar shells - Origins, and clues to the evolution of massive stars
The infrared fluxes, spatial and spectral characteristics for a sampleof 111 supergiant stars of spectral types F0 through M5 are tabulated,and correlations examined with respect to the nature of theircircumstellar envelopes. One-fourth of these objects were spatialyresolved by IRAS at 60 microns and possess extended circumstellar shellmaterial, with implied expansion ages of about 10 to the 5th yr.Inferences about the production of dust, mass loss, and the relation ofthese characteristics of the evolution of massive stars, are discussed.
| 1988 Revised MK Spectral Standards for Stars GO and Later
Not Available
| Yellow evolved stars in open clusters
This paper describes a program in which Galactic cluster post-AGBcandidates were first identified and then analyzed for clustermembership via radial velocities, monitored for possible photometricvariations, examined for evidence of mass loss, and classified ascompletely as possible in terms of their basic stellar parameters. Theintrinsically brightest supergiants are found in the youngest clusters.With increasing cluster age, the absolute luminosities attained by thesupergiants decline. It appears that the evolutionary tracks ofluminosity class II stars are more similar to those of class I than ofclass III. Only two superluminous giant star candidates are found inopen clusters.
| 1985 revised MK spectral standards : stars GO and later
Not Available
| The young SMC cluster NGC 330
A color-magnitude diagram has been obtained for the young SMC clusterNGC 330. The diagram shows a well-defined main sequence, a group of bluesupergiants, a group of red supergiants between B-V = 1.2 m and 1.6 mabout one magnitude fainter, and an empty Hertzsprung gap. Thesurrounding field is a composite of a very gold population resemblinggalactic globular clusters and a very young population. DDO and infraredphotometry strongly suggest that the cluster is metal-poor, but adefinitive measure could not be made because of calibrationdifficulties. The cluster's age is estimated at 12 million years, withthe surrounding field about 50 percent older. The cluster will provevery useful in testing stellar evolution models for young, metal-poorstars if the cluster's metallicity can be established viahigh-resolution spectroscopy.
| A photometric comparison of late-type cluster supergiants in the Magellanic Clouds and the galaxy
Measurements are made of broadband infrared photometry and 2.3-micron COindices for 20 late-type supergiants in young Magellanic Cloud blueglobular clusters and 12 late-type supergiants in southern galactic openclusters. New photoelectric B and V data for most of these stars arealso presented. These data make possible comparisons between theinfrared properties of late-type supergiants in the Galaxy and the Largeand Small Magellanic Clouds. The galactic supergiant CO indices permit amean galactic supergiant relation to be defined in the (CO)0 versus (J -K)0 plane. At a given (J K)0 color, the LMC supergiant CO indices areapproximately 0.04 mag weaker than this mean galactic value. The 30Doradus supergiants are found to follow the same sequence in the (CO)0versus (J - K)0 plane as the other LMC supergiants. A preliminarytheoretical analysis reveals that the CO indices in the LMC supergiantsare consistent with these stars being deficient in heavy elements by afactor of approximately 3.
| Revised MK Spectral Standard Stars Later than G0
Not Available
| Supergiant OH/IR stars
OH was detected toward six stars out of approximately 70 M supergiantsthat were searched for type I OH emissions, but is in most cases thoughtto not be associated with these stars. It is indicated by the results ofthis survey, in combination with earlier searches for Type II OHsupergiants, that OH luminosities are lower for Type I than Type IIsupergiants. Effects similar to a trend toward OH luminosity increaseswith IR color index have been noted for OH Miras, though these starsgenerally have smaller OH luminosities and color indexes. Results arefound to be consistent with OH supergiants having thicker dust envelopesthan most OH Miras.
| Revised MK spectral types for G, K, and M stars
A catalog of spectral types of 552 G, K, and M stars is presented, whichis classified on the revised MK system. Stellar representatives of thehalo, disk, and arm populations in all parts of the sky are included.Photoelectric V magnitudes are given, as are intensity estimates of anyfeatures which make the spectrum appear peculiar as compared to thespectrum of a similar normal star. Abundance indices are also providedin the following lines or bands: CN, barium, Fe, calcium, and CH.
| Studies of luminous stars in nearby galaxies. I. Supergiants and O stars in the Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..309H&db_key=AST
| Photoelectric two-dimensional spectral classification of M supergiants
A photoelectric system defined by eight narrow bands between 0.7 and 1.1microns has been used to measure nearly all M supergiants that have beenclassified on the MK system. The photometric TiO and CN indicesreproduce the two-dimensional MK classifications to the accuracy of theMK types themselves. Mean fluxes and spectral classifications arepresented for 128 stars.
| Evolved stars in open clusters.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJS...30..451H&db_key=AST
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Корма |
| Прямое восхождение: | 07h41m02.63s |
| Склонение: | -31°40'59.1" |
| Видимая звёздная величина: | 9.149 |
| Собственное движение RA: | -2.7 |
| Собственное движение Dec: | 1.3 |
| B-T magnitude: | 11.999 |
| V-T magnitude: | 9.385 |
Каталоги и обозначения:
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