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An updated survey of globular clusters in M 31. I. Classification and radial velocity for 76 candidate clusters
Aims.We present the first results of a large spectroscopic survey ofglobular clusters and candidate globular clusters in the nearby M 31galaxy. The survey is aimed at the classification of known candidate M31 clusters and at the study of their kinematic properties.Methods: .We obtained low-resolution spectroscopy(λ/Δλ ≃ 800-1300) for 133 targets, including76 yet-to-be-confirmed candidate clusters (i.e. with no previousspectroscopic information), 55 already-confirmed genuine M 31 clusters,and 2 uncertain candidates. Our observations allowed a reliable estimateof the target radial velocity, within a typical accuracy of ~± 20km s-1. The observed candidates have been robustly classifiedaccording to their radial velocity and shape parameters that allowed usto confidently discriminate between point sources and extended objectseven from low-spatial-resolution imagery. Results: .In our set of76 candidate clusters we found: 42 newly-confirmed bona-fide M 31clusters, 12 background galaxies, 17 foreground Galactic stars, 2 Hiiregions belonging to M 31 and 3 unclassified (possibly M 31 clusters orforeground stars) objects. The classification of a few other candidatesnot included in our survey has been also reassessed on variousobservational bases. All the sources of radial velocity estimates for M31 known globular clusters available in the literature have beencompared and checked, and a homogeneous general list has been obtainedfor 349 confirmed clusters with radial velocity. Conclusions: .Ourresults suggest that a significant number of genuine clusters(≳100) is still hidden among the plethora of known candidatesproposed by various authors. Hence our knowledge of the globular clustersystem of the M 31 galaxy is still far from complete even in terms ofsimple membership.
| The outermost cluster of M 31
We report on the identification of a new cluster in the far halo of theM 31 galaxy. The cluster, named Bologna 514 (B514) has an integratedmagnitude MV=-8.5 ± 0.6, and a radial velocity, asestimated from two independent low-resolution spectra,Vr=-456 ± 23 km s-1, which fully confirmsits membership to the M 31 system. The observed integrated spectrum isvery similar to those of classical globular clusters. Being located at≃ 4° (≃ 55 kpc in projected distance) from the center ofthe parent galaxy, B514 is by far the most remote M 31 cluster everdiscovered. Its projected position, near the galaxy major axis, and M31-centric velocity, similar to that observed in the outermost regionsof the HI rotation curve, may indicate that it belongs to the subsystemof M 31 clusters that has been recently proposed (Morrison et al. 2004 )to be part of the dynamically-cold thin disc of the galaxy.
| The Evolution of Massive Stars. I. Red Supergiants in the Magellanic Clouds
We investigate the red supergiant (RSG) content of the SMC and LMC usingmultiobject spectroscopy on a sample of red stars previously identifiedby BVR CCD photometry. We obtained high-accuracy (<1 kms-1) radial velocities for 118 red stars seen toward the SMCand 167 red stars seen toward the LMC, confirming most of these (89% and95%, respectively) as red supergiants. Spectral types were alsodetermined for most of these RSGs. We find that the distribution ofspectral types is skewed toward earlier type at lower metallicities: theaverage (median) spectral type is K5-K7 I in the SMC, M1 I in the LMC,and M2 I in the Milky Way. Our examination of the Kurucz ATLAS9 modelatmospheres suggests that the effect that metallicity has on theappearance on the TiO lines is probably sufficient to account for thiseffect, and we argue that RSGs in the Magellanic Clouds are 100 K (LMC)and 300 K (SMC) cooler than Galactic stars of the same spectral types.The colors of the Kurucz models are not consistent with thisinterpretation for the SMC, although other models (e.g., Bessell et al.)show good agreement. A finer grid of higher resolution synthetic spectraappropriate to cool supergiants is needed to better determine theeffective temperature scale. We compare the distribution of RSGs in theH-R diagram to that of various stellar evolutionary models; we find thatnone of the models produce RSGs as cool and luminous as what is actuallyobserved. This result is much larger than any uncertainty in theeffective temperature scale. We note that, were we to simply adopt theuncorrected Galactic effective scale for RSGs and apply this to oursample, then the SMC's RSGs would be underluminous compared with theLMC's, contrary to what we expect from stellar evolution considerations.In all of our H-R diagrams, however, there is an elegant sequence ofdecreasing effective temperatures with increasing luminosities;explaining this will be an important test of future stellar evolutionarymodels. Finally, we compute the blue-to-red supergiant ratio in the SMCand LMC, finding that the values are indistinguishable (~15) for the twoClouds. We emphasize that ``observed'' B/R values must be carefullydetermined if a comparison with that predicted by stellar models is tobe meaningful. The nonrotation Geneva models overestimate the number ofblue to red supergiants for the SMC, but underestimate it for the LMC;however, given the inability to produce high-luminosity RSGs in themodels that match what is observed in the H-R diagram, such adisagreement is not surprising.
| The Kinematics and Metallicity of the M31 Globular Cluster System
With the ultimate aim of distinguishing between various modelsdescribing the formation of galaxy halos (e.g., radial or multiphasecollapse and random mergers), we have completed a spectroscopic study ofthe globular cluster system of M31. We present the results of deepintermediate-resolution fiber-optic spectroscopy of several hundred ofthe M31 globular clusters using the Wide Field Fibre Optic Spectrographat the William Herschel Telescope in La Palma, Canary Islands. Theseobservations have yielded precise radial velocities (+/-12 kms-1) and metallicities (+/-0.26 dex) for over 200 members ofthe M31 globular cluster population out to a radius of 1.5d from thegalaxy center. Many of these clusters have no previous published radialvelocity or [Fe/H] estimates, and the remainder typically representsignificant improvements over earlier determinations. We presentanalyses of the spatial, kinematic, and metal abundance properties ofthe M31 globular clusters. We find that the abundance distribution ofthe cluster system is consistent with a bimodal distribution with peaksat [Fe/H]~-1.4 and -0.5. The metal-rich clusters demonstrate a centrallyconcentrated spatial distribution with a high rotation amplitude,although this population does not appear significantly flattened and isconsistent with a bulge population. The metal-poor clusters tend to beless spatially concentrated and are also found to have a strong rotationsignature.
| Fundamental plane distances to early-type field galaxies in the South Equatorial Strip. I. The spectroscopic data
Radial velocities and central velocity dispersions are derived for 238E/S0 galaxies from medium-resolution spectroscopy. New spectroscopicdata have been obtained as part of a study of the Fundamental Planedistances and peculiar motions of early-type galaxies in three selecteddirections of the South Equatorial Strip, undertaken in order toinvestigate the reality of large-scale streaming motion; results of thisstudy have been reported in Müller et al. (1998). The new APM SouthEquatorial Strip Catalog (-17fdg 5 < delta < +2fdg 5) was used toselect the sample of field galaxies in three directions: (1) 15h10 -16h10; (2) 20h30 - 21h50; (3) 00h10 - 01h30. The spectra obtained have amedian S/N per Å of 23, an instrumental resolution (FWHM) of ~ 4Å, and the spectrograph resolution (dispersion) is ~ 100 kms-1. The Fourier cross-correlation method was used to derivethe radial velocities and velocity dispersions. The velocity dispersionshave been corrected for the size of the aperture and for the galaxyeffective radius. Comparisons of the derived radial velocities with datafrom the literature show that our values are accurate to 40 kms-1. A comparison with results from Jo rgensen et al. (1995)shows that the derived central velocity dispersion have an rms scatterof 0.036 in log sigma . There is no offset relative to the velocitydispersions of Davies et al. (1987).
| The Stellar Kinematic Fields of NGC 3379
We have measured the stellar kinematic profiles of NGC 3379 along fourposition angles, using absorption lines in spectra obtained with theMultiple Mirror Telescope. We derive a far more detailed description ofthe kinematic fields through the main body of the galaxy than could beobtained from previous work. Our data extend 90" from the center, atessentially seeing-limited resolution out to 17". The derived meanvelocities and dispersions have total errors (internal and systematic)better than +/-10 km s^-1, and frequently better than 5 km s^-1, out to55". We find very weak (3 km s^-1) rotation on the minor axis interiorto 12" and no detectable rotation above 6 km s^-1 from 12" to 50" orabove 16 km s^-1 out to 90" (95% confidence limits). However, a Fourierreconstruction of the mean velocity field from all four sampled PAs doesindicate a ~5 deg twist of the kinematic major axis, in the directionopposite to the known isophotal twist. The h_3 and h_4 parameters arefound to be generally small over the entire observed region. Theazimuthally averaged dispersion profile joins smoothly at large radiiwith the velocity dispersions of planetary nebulae. Unexpectedly, wefind sharp bends in the major axis rotation curve, also visible (thoughless pronounced) on the diagonal position angles. The outermost bendclosely coincides in position with other sharp kinematic features: anabrupt flattening of the dispersion profile, and local peaks in h_3 andh_4. All of these features are in a photometrically interesting regionin which the surface brightness profile departs significantly from anr^1/4 law. Features such as these are not generally known in ellipticalgalaxies owing to a lack of data at comparable resolution. Very similarbehavior, however, is seen the kinematics of the edge-on S0 galaxy NGC3115. We discuss the suggestion that NGC 3379 could be a misclassifiedS0 galaxy; preliminary results from dynamical modeling indicate that itmay be a flattened, weakly triaxial system seen in an orientation thatmakes it appear round.
| 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.
| Nine Seasons of Velocity Measurements in the Draco and Ursa Minor Dwarf Spheroidal Galaxies with the MMT Echelle
We have used the Multiple Mirror Telescope echelle spectrograph tomeasure 112 velocities of 42 stars in the Draco and Ursa Minor dwarfspheroidal galaxies and three velocities of three foreground starsbetween 1982 April and 1990 September. We used 11 A resolution spectraobtained with the MX multifiber spectrograph at the Steward 90" to findadditional giant candidates; 5 UMi and 13 Draco stars were then observedat the MMT and added to the original sample of velocity members. Inaddition, the MX spectra were used to eliminate 74 stars in thedirection of UMI and 59 stars in Draco as likely foreground dwarfs. Wedetected 7 velocity variables, defined as those stars whose probabilityof exceeding the measured X^2^ by chance is less than 1.5%. Three ofthese stars are Carbon (C) stars (UMi K and VA 335 and Draco C1); twohave emission lines (Draco CI and UMi M). We show that the C star DracoC4, with a proper motion membership probability of 7%, has a velocityconsistent with membership. It is not surprising that these C (mostlikely CH) stars are binaries because McClure has shown that mostGalactic CH stars are in binary systems. Of the remaining 35 stars, only4 are velocity variables, with measured velocity extrema of 29.1 kms^-1^ (UMi M), 7.2 km s^-1^ (Draco XI-2), 9.0 km s^-1^ (Draco 24), and8.3 km s^-1^ (Draco 473). The velocity dispersions are 10.1 +/- 1.7 kms^-1^ for UMi, and 9.9 +/- 1.4 km s^-1^ for Draco. These dispersionschange to 10.5 +/- 2.0 for UMi, and 8.2 +?- 1.3 for Draco if weeliminate the velocity variables. Our dispersion for UMi differs fromthat of Hargreaves et al. [MNRAS, 271,693 (1994b)] by 1.3σ of thecombined errors. These velocities are combined with the one-componentKing models of Pryor & Kormendy [AJ, 100,127 (1990)] to give M/L =73 for UMi, and 77 for Draco.
| Spectroscopy of V471 Tau. I - Review of basic properties
Spectroscopic observations of the eclipsing binary V471 Tau are reportedand analyzed. Data obtained mainly in the red band at Mt. WilsonObservatory and KPNO during the period 1975-1983 are compiled inextensive tables and graphs, and the radial velocity of the K dwarfcomponent is determined using a Griffin-mask technique. Resultsdiscussed include: (1) distance 44 + or - 6 pc, (consistent withmembership in the Hyades), (2) apparent period variation consistent witha third component, (3) emissionlike features affecting theradial-velocity determination, (4) transient features consistent withthe presence of flares, and (5) phase-coherent variation in H-alpha(attributed to the action of the white-dwarf Lyman continuum emission onthe K dwarf).
| Standard Velocity Stars
Not Available
| C1 - A white-dwarf-red-dwarf spectroscopic binary
Emission lines in the spectrum of the DA white dwarf star C1 indicatedthe existence of an unresolved companion, whose spectral type wasdetermined to be approximately dM2. A radial-velocity curve for eachstar was obtained by observing the H-alpha emission line of itscompanion, and by considering the average difference between measuredand standard velocities for each star. The proper motion of C1 issimilar in magnitude to that of the Ursa Major cluster but in the wrongdirection. A lower limit for the mass of the white dwarf component iscomputed by assuming that the M dwarf is a normal main sequence star.The system shows similarities to post-common-envelope binaries.
| HZ 9 - A white-dwarf-red-dwarf spectroscopic binary in the Hyades
It is noted that the star HZ 9, a member of the Hyades, is aspectroscopic binary with a period of 0.56433 day. One component is a DAwhite dwarf and the other is a late main-sequence M star (roughlydM4.5e). The system is similar to V471 Tauri and PG 1413+01; like them,it is probably a post-common-envelope binary.
| Photoelectric radial velocities, paper 6 Heard's IAU standard stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975MNRAS.171..407G&db_key=AST
| The establishment of 21 new ninth magnitude IAU standard radial velocity stars
Not Available
| Multicolor photoelectric photometry of stars with composite spectra
Abstract image available at:http://adsabs.harvard.edu/abs/1958ApJ...128..572B
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Наблюдательные данные и астрометрия
| Созвездие: | Треугольник |
| Прямое восхождение: | 01h58m41.90s |
| Склонение: | +29°22'47.7" |
| Видимая звёздная величина: | 7.441 |
| Собственное движение RA: | 2.4 |
| Собственное движение Dec: | 1.7 |
| B-T magnitude: | 9.039 |
| V-T magnitude: | 7.573 |
Каталоги и обозначения:
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