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Dynamical mass estimates for two luminous young stellar clusters in Messier 83
Using new data from the UVES spectrograph on the ESO Very LargeTelescope and archive images from the Hubble Space Telescope, we havemeasured projected velocity dispersions and structural parameters fortwo bright young star clusters in the nearby spiral galaxy NGC5236. One cluster is located near the nuclear starburst of NGC5236, at a projected distance of 440 pc from the centre, while the otheris located in the disk of the galaxy at a projected galactocentricdistance of 2.3 kpc. We estimate virial masses for the two clusters of(4.2±0.7)×105 Mȯ and(5.2±0.8)×105 Mȯ and ages (frombroad-band photometry) of 107.1±0.2 years and108.0±0.1 years, respectively. Comparing the observedmass-to-light (M/L) ratios with simple stellar population models, wefind that the data for both clusters are consistent with a Kroupa-typestellar mass function (MF). In particular, we rule out any MF with asignificantly lower M/L ratio than the Kroupa MF, such as aSalpeter-like MF truncated at a mass of 1 Mȯ or higher.These clusters provide a good illustration of the fact that massive,globular cluster-like objects (``super star clusters'') can form at thepresent epoch even in the disks of seemingly normal, undisturbed spiralgalaxies.Based on observations collected at the European Southern Observatory,Chile under programme 71.B-0303A, and on observations obtained with theNASA/ESA Hubble Space Telescope, obtained at the Space Telescope ScienceInstitute, which is operated by the Association of Universities forResearch in Astronomy, Inc., under NASA contract NAS 5-26555.
| A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars
Rotational velocity vsin i and mean radial velocity are presented for asample of 231 Ib supergiant stars covering the spectral region F, G andK. This work is the second part of the large survey carried out with theCORAVEL spectrometer to establish the behavior of the rotation for starsevolving off the main sequence (De Medeiros & Mayor 1999). Thesedata will add constraints to the study of the rotational behavior inevolved stars, as well as solid information concerning tidalinteractions in binary systems and on the link between rotation,chemical abundance and activity in stars of intermediate masses. Basedon observations collected at the Haute-Provence Observatory,Saint-Michel, France and at the European Southern Observatory, La Silla,Chile Table 1 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/395/97
| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
| Li-rich giants: A survey based on IRAS colours
In a previous work we studied the IRAS colours of known Li-rich redgiants and showed that they have flux ratiosF12/F25 and F25/F60 in welldefined ranges. By using this result as a selection criterion, weprepared a list of 280 IRAS Point Source candidates to be Li-rich giantstars. Up to the present we have obtained spectra for 57% of our targetlist. We identified five stars showing a strong LiI 670.079 nm line andsix ones with a Li line of medium strength. Most of the candidates showfeatures typical of normal giants having circumstellar dust, asindicated by their IRAS colours. Observations collected at theLaboratorio Nacional de Astrofisica - LNA, Brazil; Observatoire de HauteProvence - OHP, France; European Southern Observatory - ESO, Chile.
| Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
| Photometry of F-K type bright giants and supergiants. I - Intermediate band and H-Beta observations
Over 1500 observations of 560 bright giants and supergiants of types F-Kare presented and compared to the observations by Gray and Olsen (1991).The present results include intermediate-band which is slightlydifferent from the Stromgren data by Gray and Olsen due to a differentwidth for the v filter. A systematic difference in m(1) - M(1) withdecreasing temperature is noted in the two H-Beta data sets, and thecorrelations are defined.
| An IRAS survey of IR excesses in G-type stars
The IRAS Point Source Catalog has been searched for infrared sourcesassociated with G-type stars. Of the 3803 IRAS sources identified inthis way, 28 were found to have enhanced emission at lambda greater than25 microns characteristic of circumstellar material. The majority of theIR-excess stars were supergiants whose inferred mass loss rates werefound to be comparable to those of red giants. One of the stars, IRAS11059-7721, is a G main-sequence star whose circumstellar medium (CSM)has 20,000 times the optical depth of Vega's CSM. The physicalcharacteristics of the circumstellar emission for this sample aredescribed, and several scenarios for its existence are examined in lightof the IRAS data.
| Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
| O stars and supergiants south of declination -53 0.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976AJ.....81..116H&db_key=AST
| Five-channel photometry of cepheids and supergiants in the southern Milky Way.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...24..413P&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Regolo |
| Ascensione retta: | 16h29m45.00s |
| Declinazione: | -57°45'21.0" |
| Magnitudine apparente: | 6.06 |
| Distanza: | 469.484 parsec |
| Moto proprio RA: | -3.1 |
| Moto proprio Dec: | -2.2 |
| B-T magnitude: | 7.983 |
| V-T magnitude: | 6.225 |
Cataloghi e designazioni:
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