- ID:
- ivo://CDS.VizieR/J/A+A/551/A81
- Title:
- NGC 6951 intensity and velocity maps
- Short Name:
- J/A+A/551/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas inflowing along stellar bars is often stalled at the location of circumnuclear rings, which form an effective reservoir for massive star formation and thus shape the central regions of galaxies. However, how exactly star formation proceeds within these circumnuclear starburst rings is the subject of debate. Two main scenarios for this process have been put forward. In the first, the onset of star formation is regulated by the total amount of gas present in the ring with star forming starting, once a mass threshold has been reached, in "random" positions within the ring like "popcorn". In the second, star formation primarily takes place near the locations where the gas enters the ring. This scenario has been dubbed "pearls-on-a-string". Here we combine new optical IFU data covering the full stellar bar with existing multiwavelength data to study the 580pc radius circumnuclear starburst ring in detail in the nearby spiral galaxy NGC 6951. Using Hubble Space Telescope (HST) archival data together with SAURON and OASIS IFU data, we derive the ages and stellar masses of star clusters, as well as the total stellar content of the central region.
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1052. NGC 2516 membership list
- ID:
- ivo://CDS.VizieR/J/A+A/641/A51
- Title:
- NGC 2516 membership list
- Short Name:
- J/A+A/641/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We wish to measure the cool star rotation period distribution for the Pleiades-age rich open cluster NGC 2516 and use it to determine whether cluster-to-cluster variations exist in otherwise identical open clusters. We obtained 42d-long time-series CCD photometry of NGC 2516 in the V and Ic filters using the Yale 1m telescope at CTIO and performed a number of related analyses, including PSF-based time-series photometry. Our data are complemented with additional information from several photometric datasets, literature radial velocities, and Gaia DR2 astrometry. All available data are used to construct an integrated membership list for NGC 2516, containing 844 stars in our ~1 degree field of view. We derived 308 rotation periods for late-F to mid-M cluster members from our photometry. We identified an additional 247 periodic M dwarf stars from a prior study as cluster members, and used these to construct a 555-star rotation period distribution for NGC 2516. The colour-period diagram (in multiple colours) has almost no outliers and exhibits the anticipated triangular shape, with a diagonal slow rotator sequence that is preferentially occupied by the warmer stars along with a flat fast rotator sequence that is preferentially populated by the cooler cluster members. We also find a group of extremely slowly rotating M dwarfs (10d<P<23d), forming a branch in the colour-period diagram which we call the 'extended slow rotator sequence'. This, and other features of the rotational distribution can also be found in the Pleiades, making the colour-period diagrams of the two clusters nearly indistinguishable. A comparison with the well-studied (and similarly aged) open cluster M 35 indicates that the cluster's rotational distribution is also similarly indistinguishable from that of NGC 2516. Those for the open clusters M 50 and Blanco 1 are similar, but data issues for those clusters make the comparisons somewhat more ambiguous. Nevertheless, we demonstrate the existence of a representative zero-age main sequence (ZAMS) rotational distribution and provide a simple colour-independent way to represent it. We perform a detailed comparison of the NGC 2516 rotation period data with a number of recent rotational evolution models. Using X-ray data from the literature, we also construct the first rotation-activity diagram for solar-type stars in NGC 2516, one that we find is essentially indistinguishable from those for the Pleiades and Blanco 1. The two clusters NGC 2516 and Pleiades can be considered twins in terms of stellar rotation and related properties (and M 35, M 50, and Blanco 1 are similar), suggesting that otherwise identical open clusters also have intrinsically similar cool star rotation and activity distributions.
1053. NGC3447/NGC3447A maps
- ID:
- ivo://CDS.VizieR/J/A+A/610/A8
- Title:
- NGC3447/NGC3447A maps
- Short Name:
- J/A+A/610/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Local Group (LG) Analogs (LGAs) are galaxy associations dominated by a few bright spirals reminiscent of the LG. The NGC3447/NGC3447A system is a member of the LGG 225 group, a nearby LGA. This system is considered a physical pair composed of an intermediate-luminosity late-type spiral, NGC3447 itself, and an irregular companion, NGC3447A, linked by a faint, short filament of matter. A ring-like structure in the NGC3447 outskirts has been emphasised by Galaxy Evolution Explorer (GALEX) observations. This work aims to contribute to the study of galaxy evolution in low-density environments, a favourable habitat to highly effective encounters, shedding light on the evolution of the NGC3447/NGC3447A system. We performed a multi-{lambda} analysis of the surface photometry of this system to derive its spectral energy distribution and structural properties using ultraviolet (UV), Swift UVOT, and optical Sloan Digital Sky Survey (SDSS) images complemented with available far-IR observations. We also characterised the velocity field of the pair using two-dimensional H{alpha} kinematical observations of the system obtained with PUMA Fabry-Perot interferometer at the 2.1m telescope of San Pedro Martir (Mexico). All these data are used to constrain smooth particle hydrodynamic simulations with chemo-photometric implementation to shed light on the evolution of this system. The luminosity profiles, from UV to optical wavelengths, are all consistent with the presence of a disc extending and including NGC3447A. The overall velocity field does not emphasise any significant rotation pattern, rather a small velocity gradient between NGC3447 and NGC3447A. Our simulation, detached from a large grid explored to best-fit the global properties of the system, suggests that this arises from an encounter between two halos of equal mass.
- ID:
- ivo://CDS.VizieR/J/A+A/516/A4
- Title:
- NGC1600, NGC4125, NGC7619 extended spectroscopy
- Short Name:
- J/A+A/516/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high quality long slit spectra along the major and minor axes out to 1.5-2R_e_ (14-22kpc) of three bright elliptical galaxies (NGC1600, NGC4125, NGC7619) obtained at the Hobby-Eberly Telescope (HET). We derive stellar kinematic profiles and Lick/IDS indices (H{beta}, Mgb, Fe_{5015}, Fe_{5270}, Fe_{5335}, Fe_{5406}). Moreover, for NGC4125 we derive gas kinematics and emission line strengths. We model the absorption line strengths using Simple Stellar Populations models that take into account the variation of {alpha}/Fe and derive ages, total metallicity and element abundances. Overall, we find that the three galaxies have old and {alpha}/Fe overabundant stellar populations with no significant gradients. The metallicity is supersolar at the center with a strong negative radial gradient. For NGC4125, several pieces of evidence point to a recent dissipational merger event. We calculate the broad band color profiles with the help of SSP models. All of the colors show sharp peaks at the center of the galaxies, mainly caused by the metallicity gradients, and agree well with the measured colors. Using the Schwarzschild's axisymmetric orbit superposition technique, we model the stellar kinematics to constrain the dark halos of the galaxies. We use the tight correlation between the Mgb strength and local escape velocity to set limits on their extent by testing different halo sizes. Logarithmic halos cut at 60kpc minimize the overall scatter of the Mgb-V_esc_ relation. Larger cutoff radii are found if the dark matter density profile is decreasing more steeply at large radii.
- ID:
- ivo://CDS.VizieR/J/A+A/322/460
- Title:
- NGC 3680 photometry and radial velocities
- Short Name:
- J/A+A/322/460
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on new, accurate photometry, radial velocities, and proper motions for the intermediate-age open cluster NGC 3680, we identify individual single and binary cluster members and field stars in the colour-magnitude diagram (CMD). This basic step turns out to be crucial for a proper understanding of the cluster CMD: ~60% of the stars are found to be field stars, and over 50% of the cluster stars are binaries. No bona fide cluster star is found more than 1.5mag below the turnoff, and cluster stars below 1.4M_{sun}_ are only found in binary systems. The total present mass of NGC 3680 is ~100M_{sun}_, excluding any as yet unseen stellar remnants, and its half-mass radius is 3.3' (1.2pc). Comparison with plausible IMFs indicates that only ~3% of the original stars and <~10% of the mass now survive, ~30% of the initial mass being in the form of massive stars that have now completed their evolution, and ~60% in low-mass stars which may now be located in a distant cluster halo or perhaps have been lost entirely. The single main-sequence cluster members form an extremely tight sequence in the CMD, with E_(b-y)_=0.034 and [Fe/H]=+0.11. A direct fit to the Hyades main sequence yields (m-M)_0_=10.5+/-0.2 for NGC 3680. Isochrones from several stellar models have been fit to the cluster sequence. When based on consistent uvby colour transformations and the above cluster parameters, these fits are very stable and show that standard models are not acceptable for stars with the turnoff mass of NGC 3680. Overshooting models perform much better, but further refinement of the overshooting formalism seems to be needed. The age derived for NGC 3680 is 1.45+/-0.3Gyr. The limiting factor in a precise comparison of theory and observations is now the transformation from theoretical to observed parameters, particularly (broad-band) colours.
- ID:
- ivo://CDS.VizieR/J/ApJ/602/685
- Title:
- NGC 5128 planetary nebulae
- Short Name:
- J/ApJ/602/685
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The halos of elliptical galaxies are faint and difficult to explore, but they contain vital clues to both structure and formation. We present the results of an imaging and spectroscopic survey for planetary nebulae (PNe) in the nearby elliptical NGC 5128. We extend the work of Hui and coworkers (Cat. <J/ApJ/449/592>) well into the halo of the galaxy - out to distances of 100 and 50kpc along the major and minor axes. We now know of 1141 PNe in NGC 5128, 780 of which are confirmed. Of these 780 PNe, 349 are new from this survey, and 148 are at radii beyond 20kpc. PNe exist at distances up to 80kpc (~15r_e_), showing that the stellar halo extends to the limit of our data.
- ID:
- ivo://CDS.VizieR/J/ApJ/414/454
- Title:
- NGC 3379 planetary nebulae radial velocities
- Short Name:
- J/ApJ/414/454
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a radial velocity survey of planetary nebulae (PNs) in the normal elliptical galaxy NGC 3379 performed with the Kitt Peak 4m telescope and the NESSIE multifiber spectrograph. In two half-nights, we measured 29 PNs with projected galactocentric distances between 0.4 and 3.8 effective radii (1<R<10kpc) with an observational uncertainty of ~7km/s. These data extend 3 times further into the halo than any previous absorption-line velocity study. The velocity dispersion and photometric profile of the galaxy agrees extremely well with that expected from a constant mass-to-light ratio, isotropic orbit Jaffe model with M/L_B_~7; the best-fitting anisotropic models from a quadratic programming algorithm also give M/L_B_~7. The data are consistent with models that contain no dark matter within 3.5 effective radii of the galaxy's nucleus.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A11
- Title:
- NGC 1316/1317 planetary nebula kinematics
- Short Name:
- J/A+A/539/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present positions and velocities for 796 planetary nebulae (PNe) in the Fornax Brightest Cluster Galaxy NGC 1316 (Fornax A). The planetary nebulae and existing kinematics are used to explore the rotation of this merger remnant and constrain dynamical models. Using FORS2 on the VLT, the PN velocities were measured using a counter-dispersed slitless-spectroscopy technique that produced the largest-to-date sample outside of the Local Group. Spherical, non-rotating, constant-anisotropy Jeans models were con- strained by observations of the planetary nebulae and existing integrated light spectra.
1059. NGC 5128 PN. III.
- ID:
- ivo://CDS.VizieR/J/ApJ/449/592
- Title:
- NGC 5128 PN. III.
- Short Name:
- J/ApJ/449/592
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the halo dynamics and mass distributions of the nearby giant elliptical galaxy NGC 5128 using planetary nebulae (PNs) as test particles. Radial velocities of 433 PNs were obtained with multifiber spectrographs on both the Anglo-Australian Telescope (AAT) and the Cerro Tololo Inter-American Observatory (CTIO) 4m telescope. The velocities were measured from the [O III]{lambda}5007 emission line with a typical 1{sigma} error of +/-4km/s and +/-30km/s for the AAT and the CTIO data, respectively. These PNs cover the entire galaxy to a radius of 10kpc and extend along the photometric major axis out to 20kpc. The PN velocity field shows the distinctive characteristics of a triaxial potential: the galaxy's rotation axis is offset from its photometric minor axis by 39+/-10deg; the rotation axis and the line of maximum rotation are likely not orthogonal. We also find that the ordered motions of the stars become more important with increasing radius compared to their random motions. The rotation reaches approximately 100km/s and 50km/s along the photometric major and minor axes, giving a local V/{sigma} ratio of about 1.0 and 0.5, respectively. The aximuthal variation of the velocity dispersion appears to be modulated by rotation, i.e., it reaches a maximum where the largest rotation is observed and drops to a minimum at zero rotation. The amplitude of this modulation is about 20km/s, compared to a mean dispersion velocity of 110km/s. The kinematics of the globular clusters depend on the metallicity. Taking [Fe/H]=-1.0 as the dividing point, the metal-poor clusters do not show any significant rotation. However the metal-rich clusters show both major and minor axis rotation, and the amplitudes of the rotation are similar to that of the PNs. The stellar velocity dispersion measured from absorption-line spectra together with an H{alpha} rotation curve of the dust lane suggest that the stellar orbits are isotropic and the mass-to-light ratio (M/L_B_) is 3.9 in the central region of the galaxy. By applying the isotropic Jeans equation to the observed PN major axis rotation and velocity dispersion, we show that the M/L_B_ increases with radius, suggesting the presence of dark matter in the halo. Within a 25kpc radius, the total mass of the galaxy is 3.1x10^11^M_{sun}_ and M/L_B_=10. The rotation velocity of the recently detected H I ring at a radius of 15kpc confirms our mass model. The misalignment of the rotation axis relative to the photometric minor axis, combined with the knowledge of the dust lane orientation, allows us to uniquely determine the observer's viewing direction. The true shape of the galaxy is nearly spherical yet sufficiently triaxial to impose a distinctive gravitational signature on the kinematics.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A147
- Title:
- NGC 2070 point sources radial velocities
- Short Name:
- J/A+A/614/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce VLT-MUSE observations of the central 2'x2' (30x30pc) of the Tarantula Nebula in the Large Magellanic Cloud. The observations provide an unprecedented spectroscopic census of the massive stars and ionised gas in the vicinity of R136, the young, dense star cluster located in NGC 2070, at the heart of the richest star-forming region in the Local Group. Spectrophotometry and radial-velocity estimates of the nebular gas (superimposed on the stellar spectra) are provided for 2255 point sources extracted from the MUSE datacubes, and we present estimates of stellar radial velocities for 270 early-type stars (finding an average systemic velocity of 271+/-41km/s). We present an extinction map constructed from the nebular Balmer lines, with electron densities and temperatures estimated from intensity ratios of the [SII], [NII], and [SIII] lines. The interstellar medium, as traced by H{alpha} and [NII] {lambda}6583, provides new insights in regions where stars are probably forming. The gas kinematics are complex, but with a clear bi-modal, blue- and red-shifted distribution compared to the systemic velocity of the gas centred on R136. Interesting point-like sources are also seen in the eastern cavity, western shell, and around R136; these might be related to phenomena such as runaway stars, jets, formation of new stars, or the interaction of the gas with the population of Wolf-Rayet stars. Closer inspection of the core reveals red-shifted material surrounding the strongest X-ray sources, although we are unable to investigate the kinematics in detail as the stars are spatially unresolved in the MUSE data. Further papers in this series will discuss the detailed stellar content of NGC 2070 and its integrated stellar and nebular properties.
