- ID:
- ivo://CDS.VizieR/J/PASP/110/1172
- Title:
- NGC 7789 radial velocities
- Short Name:
- J/PASP/110/1172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of 597 radial velocity observations for 112 stars in the ~1.6Gyr old open cluster NGC 7789 have been obtained since 1979 with the radial velocity spectrometer at the Dominion Astrophysical Observatory. The mean cluster radial velocity is -54.9+/-0.12km/s and the dispersion is 0.86km/s, from 50 constant velocity stars selected as members from this radial velocity study and the 1981 proper motion study of McNamara & Solomon (1981A&AS...43..337M). Twenty-five stars (32%) among 78 members are possible radial velocity variable stars, but no orbits are determined because of the sparse sampling. Seventeen stars are radial velocity nonmembers, while the membership estimates of six stars are uncertain. There is a hint that the observed velocity dispersion falls off at large radius: this may be due to the inclusion of long-period binaries preferentially in the central area of the cluster. The known radial velocity variables also seem to be more concentrated toward the center than members with constant velocity. Although this is significant at only the 85% level, when combined with the similar result of Raboud & Mermilliod (1994A&A...289..121R) for three other clusters, the data strongly support the conclusion that mass segregation is being detected.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3130
- Title:
- NGC5694 radial velocities and metallicities
- Short Name:
- J/MNRAS/446/3130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the kinematics of the remote globular cluster NGC 5694 based on GIRAFFE@VLT medium-resolution spectra. A sample of 165 individual stars selected to lie on the red giant branch in the cluster colour-magnitude diagram was considered. Using radial velocity and metallicity from Calcium triplet, we were able to select 83 bona fide cluster members. The addition of six previously known members leads to a total sample of 89 cluster giants with typical uncertainties <=1.0km/s in their radial velocity estimates. The sample covers a wide range of projected distances from the cluster centre, from ~0.2arcmin to 6.5arcmin =~23 half-light radii (r_h_). We find only very weak rotation, as typical of metal-poor globular clusters. The velocity dispersion gently declines from a central value of {sigma}=6.1km/s to {sigma}=~2.5km/s at ~2arcmin=~7.1r_h_, then it remains flat out to the next (and last) measured point of the dispersion profile, at ~4arcmin =~14.0r_h_, at odds with the predictions of isotropic King models. We show that both isotropic single-mass non-collisional models and multimass anisotropic models can reproduce the observed surface brightness and velocity dispersion profiles.
1063. NGC 2354 red giants
- ID:
- ivo://CDS.VizieR/J/A+AS/134/301
- Title:
- NGC 2354 red giants
- Short Name:
- J/A+AS/134/301
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new Coravel radial-velocity observations and photoelectric photometry in the UBV, DDO and Washington systems for a sample of red giant candidates in the field of the intermediate-age open cluster NGC 2354. Photometric membership probabilities show very good agreement with those obtained from Coravel radial velocities. The analysis of the photometric and kinematical data allow us to confirm cluster membership for 9 red giants, one of them being a spectroscopic binary, while 4 confirmed spectroscopic binaries appear to be probable members. We have also discovered 4 spectroscopic binaries not belonging to the cluster. A mean radial velocity of (33.40+/-0.27)km/s and a mean reddening E(B-V)=0.13+/-0.03 were derived for the cluster giants. NGC 2354 has a mean ultraviolet excess <{delta}(U-B)>=-0.03+/-0.01, relative to the field K giants, and a mean new cyanogen anomaly {Delta}CN=-0.035+/-0.007, both implying [Fe/H]=~-0.3. The moderately metal-poor character of NGC 2354 is confirmed using five different metal abundance indicators of the Washington system. The cluster giant branch is formed by a well defined clump of 7 stars and 4 stars with high membership probabilities seem to define an ascending giant branch. The whole red giant locus cannot be reproduced by any theoretical track.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A85
- Title:
- NGC3627S and NGC3627N CO(1-0) data cubes
- Short Name:
- J/A+A/597/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To gain insight into the expected gas dynamics at the interface of the Galactic bar and spiral arms in our own MilkyWay galaxy, we examine as an extragalactic counterpart the evidence for multiple distinct velocity components in the cold, dense molecular gas populating a comparable region at the end of the bar in the nearby galaxy NGC 3627. We assemble a high resolution view of molecular gas kinematics traced by CO(2-1) emission and extract line-of-sight velocity profiles from regions of high and low gas velocity dispersion. The high velocity dispersions arise with often double-peaked or multiple line-profiles. We compare the centroids of the different velocity components to expectations based on orbital dynamics in the presence of bar and spiral potential perturbations. A model of the region as the interface of two gas-populated orbits families supporting the bar and the independently rotating spiral arms provides an overall good match to the data. An extent of the bar to the corotation radius of the galaxy is favored. Using NGC 3627 as an extragalactic example, we expect situations like this to favor strong star formation events such as observed in our own Milky Way since gas can pile up at the crossings between the orbit families. The relative motions of the material following these orbits is likely even more important for the build up of high density in the region. The surface densities in NGC 3627 are also so high that shear at the bar end is unlikely to significantly weaken the star formation activity. We speculate that scenarios in which the bar and spiral rotate at two different pattern speeds may be the most favorable for intense star formation at such interfaces.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A70
- Title:
- NGC 330 seen by MUSE. II.
- Short Name:
- J/A+A/652/A70
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Observations of massive stars in open clusters younger than 8 Myr have shown that a majority of them are in binary systems, most of which will interact during their life. While these can be used as a proxy of the initial multiplicity properties, studying populations of massive stars older than ~20Myr allows us to probe the outcome of such interactions after a significant number of systems have experienced mass and angular momentum transfer and possibly even merged. Using multi-epoch integral-field spectroscopy, we aim to investigate the multiplicity properties of the massive-star population in the dense core of the ~40Myr-old cluster NGC 330 in the Small Magellanic Cloud in order to search for possible imprints of stellar evolution on the multiplicity properties. We obtained six epochs of VLT/MUSE observations operated in wide-field mode with the extended wavelength setup and supported by adaptive optics.We extract spectra and measure radial velocities for stars brighter than m_F814W_=19. We identify single-lined spectroscopic binaries through significant RV variability with a peak-to-peak amplitude larger than 20km/s. We also identify double-lined spectroscopic binaries, and quantify the observational biases for binary detection. In particular, we take into account that binary systems with similar line strength are difficult to detect in our data set. The observed spectroscopic binary fraction among the stars brighter than m_F814W_=19 (~5.5M_{sun}_ on the main sequence) is f^obs^_SB_=13.2+/-2:0%. Considering period and mass ratio ranges from log(P)=0.15-3.5 (about 1.4 to 3160d), and q=0.1-1.0, and a representative set of orbital parameter distributions, we find a bias-corrected close binary fraction of f_cl_=34^+8^_-7_%. This fraction seems to decline for the fainter stars, which indicates either that the close binary fraction drops in the B-type domain, or that the period distribution becomes more heavily weighted towards longer orbital periods.We further find that both fractions vary strongly in different regions of the color-magnitude diagram that corresponds to different evolutionary stages. This probably reveals the imprint of the binary history of different groups of stars. In particular, we find that the observed spectroscopic binary fraction of Be stars (f^obs^_SB_=2+/-2%) is significantly lower than the one of B-type stars (f^obs^_SB_=9+/-2%). In this work we provide the first homogeneous RV study of a large sample of B-type stars at a low metallicity ([Fe/H]<~-1.0). The overall bias-corrected close binary fraction (log(P)<3.5d) of the B-star population in NGC 330 is lower than the one reported for younger Galactic and LMC clusters in previous works. More data are, however, needed to establish whether the observed differences result from an age or a metallicity effect.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/1993
- Title:
- NGC 1893 stars LSR velocities
- Short Name:
- J/MNRAS/477/1993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- OB associations are the prevailing star-forming sites in the Galaxy. Up to now, the process of how OB associations were formed remained a mystery. A possible process is self-regulating star formation driven by feedback from massive stars. However, although a number of observational studies uncovered various signposts of feedback-driven star formation, the effectiveness of such feedback has been questioned. Stellar and gas kinematics is a promising tool to capture the relative motion of newborn stars and gas away from ionizing sources. We present high-resolution spectroscopy of stars and gas in the young open cluster NGC 1893. Our findings show that newborn stars and the tadpole nebula Sim 130 are moving away from the central cluster containing two O-type stars, and that the time-scale of sequential star formation is about 1Myr within a 9pc distance. The newborn stars formed by feedback from massive stars account for at least 18 per cent of the total stellar population in the cluster, suggesting that this process can play an important role in the formation of OB associations. These results support the self-regulating star formation model.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/183
- Title:
- NGC1271 stellar kinematics
- Short Name:
- J/ApJ/808/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2kpc and a large bulge stellar velocity dispersion of 276km/s for its K-band luminosity of 8.9x10^10^L_{sun}_. We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observations from the Near-infrared Integral Field Spectrometer on the Gemini North telescope assisted by laser guide star adaptive optics, large-scale integral field unit observations with PPAK at the Calar Alto Observatory, and Hubble Space Telescope WFC3 imaging observations. We are able to map out the stellar kinematics both on small spatial scales, within the black hole sphere of influence, and on large scales that extend out to four times the galaxy's effective radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise in the velocity dispersion. Through the use of orbit-based stellar dynamical models, we determine that the black hole has a mass of (3.0^+1.0^_-1.1_)x10^9^M_{sun}_ and the H-band stellar mass-to-light ratio is 1.40^+0.13^_-0.11_{gamma}_{sun}_ ({sigma} uncertainties). NGC 1271 occupies the sparsely populated upper end of the black hole mass distribution but is very different from the brightest cluster galaxies (BCGs) and giant elliptical galaxies that are expected to host the most massive black holes. Interestingly, the black hole mass is an order of magnitude larger than expectations based on the galaxy's bulge luminosity but is consistent with the mass predicted using the galaxy's bulge stellar velocity dispersion. More compact, high-dispersion galaxies need to be studied using high spatial resolution observations to securely determine black hole masses, as there could be systematic differences in the black hole scaling relations between these types of galaxies and the BCGs/giant ellipticals, thereby implying different pathways for black hole and galaxy growth.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/3776
- Title:
- NGC 3115 Stellar Populations and Kinematics
- Short Name:
- J/MNRAS/487/3776
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a combination of the Schwarzschild orbit-superposition dynamical modelling technique with the spatially-resolved mean stellar age and metallicity maps to uncover the formation history of galaxies. We apply this new approach to a remarkable 5-pointing mosaic of VLT/MUSE observations obtained by Guerou et al. (2016A&A...591A.143G, Cat. J/A+A/591/A143) extending to a maximum galactocentric distance of ~120'' (5.6kpc) along the major axis, corresponding to ~2.5R_e. Our method first identifies 'families' of orbits from the dynamical model that represent dynamically distinct structures of the galaxy. Individual ages and metallicities of these components are then fit for using the stellar-population information. Our results highlight components of the galaxy that are distinct in the combined stellar dynamics/populations space, which implies distinct formation paths. We find evidence for a dynamically-cold, metal-rich disk, consistent with a gradual in-situ formation. This disk is embedded in a generally-old population of stars, with kinematics ranging from dispersion-dominated in the centre to an old, diffuse, metal-poor stellar halo at the extremities. We find also a direct correlation between the dominant dynamical support of these components, and their associated age, akin to the relation observed in the Milky Way. This approach not only provides a powerful model for inferring the formation history of external galaxies, but also paves the way to a complete population-dynamical model.
- ID:
- ivo://CDS.VizieR/J/AJ/138/159
- Title:
- NGC 6819 stellar radial-velocity and photometry
- Short Name:
- J/AJ/138/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the current results from our ongoing radial-velocity (RV) survey of the intermediate-age (2.4Gyr) open cluster NGC 6819. Using both newly observed and other available photometry and astrometry, we define a primary target sample of 1454 stars that includes main-sequence, subgiant, giant, and blue straggler stars, spanning a magnitude range of 11<=V<=16.5 and an approximate mass range of 1.1-1.6M_{sun}_. Our sample covers a 23 arcminute (13pc) square field of view centered on the cluster. We have measured 6571 radial velocities for an unbiased sample of 1207 stars in the direction of the open cluster NGC 6819, with a single-measurement precision of 0.4km/s for most narrow-lined stars. We use our RV data to calculate membership probabilities for stars with >=3 measurements, providing the first comprehensive membership study of the cluster core that includes stars from the giant branch through the upper main sequence. We identify 480 cluster members. Additionally, we identify velocity-variable systems, all of which are likely hard binaries that dynamically power the cluster.
- ID:
- ivo://CDS.VizieR/V/103
- Title:
- NGP G5-M stars RV, DDO and BV photometry
- Short Name:
- V/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocities are given for some 900 stars within 15{deg} of the North Galactic Pole, including almost all such stars classified G5 or latter in the Henry-Draper Catalogue (Cat. <III/135>). Luminosities, two-dimensional spectral classes, composition indices, and distances are derived for the majority of the sample through DDO and BV photometry. The radial velocities come from several instruments (see the "Note(2)" section below) ; the BV and DDO photometries were obtained at Mount Laguna Observatory, with the San Diego State University 24-inch Schmidt reflector.
