- ID:
- ivo://CDS.VizieR/J/MNRAS/365/401
- Title:
- New planetary nebulae in LMC
- Short Name:
- J/MNRAS/365/401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report our initial discovery of 73 new planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) following confirmatory 2dF spectroscopy on the Anglo-Australian Telescope. Preliminary candidate sources come from a 10 per cent sub-area of our new deep, high-resolution H{alpha} map of the central 25deg^2^ of the LMC obtained with the UK Schmidt Telescope. The depth of the high-resolution map was extended to R_equiv_~22 for H{alpha} (4.5x10^-17^erg/cm^2^/s/{AA}) by a process of multi-exposure median co-addition of a dozen 2-h H{alpha} exposures. The resulting map is at least 1-mag deeper than the best wide-field narrow-band LMC images currently available. This depth, combined with our selection technique, has also led to the discovery of extended asymptotic giant branch (AGB) haloes around many new and previously known LMC PNe for the first time. Once complete, our new survey is expected to triple the LMC PN population and have significant implications for the LMC PN luminosity function, kinematics, abundance gradients, chemical evolution and, via study of the AGB haloes, the initial to final mass relation for low- to intermediate-mass stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/123/269
- Title:
- New SMC planetary nebulae
- Short Name:
- J/AJ/123/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the ESO 2.2m telescope with the 8Kx8K mosaic CCD, we have surveyed 2.8deg^2^ (~1.6{deg}x1.7{deg}) of the Small Magellanic Cloud (SMC) to search for faint planetary nebulae (PNs); 34 PNs were previously known in this central region. We identified 25 new PNs, all faint and spectroscopically confirmed.
- ID:
- ivo://CDS.VizieR/J/AcA/67/363
- Title:
- New star clusters in the Magellanic system
- Short Name:
- J/AcA/67/363
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial distribution, chemical composition and age distribution yield important information about the formation scenario of the whole Magellanic System. Using deep photometric maps compiled in the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) we present the most complete catalog of star clusters in the Magellanic System ever constructed from homogeneous, long time-scale photometric data. In this second paper of the series, we show the collection of star clusters found in the area of about 360 square degrees in the MBR and in the outer regions of the SMC. Our sample contains 198 visually identified star cluster candidates, 75 of which were not listed in any of the previously published catalogs. The new discoveries are mainly young small open clusters or clusters similar to associations.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A3
- Title:
- New survey of supergiants in the MCs
- Short Name:
- J/A+A/578/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this study, we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership to the clouds. Around two hundred new RSGs have been detected, hinting at a yet to be observed large population. Using near and mid infrared photometry we study the brightness distribution of these stars, the onset of mass-loss and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid and near infrared photometry to improve the observational efficiency of similar programs as this.
365. NGC 2004
- ID:
- ivo://CDS.VizieR/J/AJ/102/137
- Title:
- NGC 2004
- Short Name:
- J/AJ/102/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a new CCD photometric investigation of stars in the field of the LMC cluster NGC 2004 are reported and discussed. B, V photometry is given for more than 1500 objects, the large majority to be ascribed to the cluster. A new color-magnitude diagram is presented. It shows a well-defined blue sequence (BS) of H-burning stars, running from V~=21mag up to V~=13mag, together with a group of cluster He-burning red supergiants with V~=13mag and a clump of field red giants at about V~=19 mag. Theoretical evolutionary computations are reported covering the range of massive stars evolving in the cluster. These evolutionary tracks can match the observed CM diagram provided that a low efficiency of the surface convection (a low value of the mixing length) is adopted. Comparison of the theoretical luminosity function with the upper portion of the observed BS distribution suggests a cluster age of about 8 million years, in agreement with previous evaluations. The completeness of the sample and the contribution of field stars have been estimated. The CM distribution of cluster stars has been compared with the results of synthetic clusters based on the adopted evolutionary scenario. We find that the observed distribution of cluster stars in the different evolutionary phases appears in good agreement with prediction based on theoretical evolutionary lifetimes. Moreover, the distribution of H-burning stars agrees with a Salpeter distribution in the whole range 2<=M/M_{sun}_<=20. After a short review of the current theoretical scenario concerning massive stars, the CM diagram of field stars is discussed, reaching the conclusion that the observed clump of red giants is the natural consequence of the peculiar large lifetimes in the central He burning phase of stars with M~=3M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/472/577
- Title:
- NGC 330 Be stars and binaries
- Short Name:
- J/A+A/472/577
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of hot stars belonging to the young cluster SMC-NGC 330 and its surrounding region were obtained with the VLT-GIRAFFE facilities in MEDUSA mode. We investigated the B and Be star properties and proportions in this environment of low metallicity. We also searched for rapid variability in Be stars using photometric databases. Using spectroscopic measurements, we characterized the emission and properties of Be stars. By cross-correlation with photometric databases such as MACHO and OGLE, we searched for binaries in our sample of hot stars, as well as for short-term variability in Be stars. We report on the global characteristics of the Be star sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/297/582
- Title:
- NGC 2213 BR photometry
- Short Name:
- J/ApJ/297/582
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The age of the LMC red globular cluster NGC 2213 has been estimated as 1.3+/-0.5x10^9^yr from a color-magnitude diagram, derived from CCD photometry, that reveals the cluster main sequence. The accuracy of the age estimate, however, is limited by uncertainly in the LMC distance modulus, by uncertainty in the cluster metal abundance which appears to lie in the range one-half to one-sixth solar, by uncertainty in the reddening of the cluster, and by uncertainty in the extent to which the theoretical isochrones used for the age dating are affected by the neglect, in standard stellar models, of the interior mixing caused by convective overshoot in the stellar cores. Using the adopted reddening of E(B-V)=0.09 and assuming Y=0.2, isochrone best fits to the cluster main sequence are found for [M/H]=-0.3 if (m-M)0=18.7 and for [M/H]=-0.7 if (m-M)0=18.2. After allowance for the possible effects of convective overshoot, the corresponding ages are 0.9^+0.5^_-0.3_ and 1.6^+0.8_^-0.4_x10^9^yr. Plausible alterations in the adopted reddening value and the adopted helium abundance also yield ages within these limits.
- ID:
- ivo://CDS.VizieR/J/ApJ/298/544
- Title:
- NGC 121 BR photometry
- Short Name:
- J/ApJ/298/544
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The age of the SMC globular cluster NGC 121 is found from main-sequence isochrone fitting to be 12+/-2x10^9^yr if a distance modulus that assumes Mv=+0.6 for the field RR Lyrae variables near the cluster is used. If instead (m-M)o = 19.3, then the cluster age is 9+/-2x10^9^yr. The cluster is known to contain both RR Lyrae variables and a marginal carbon star; comparison with theoretical models indicates no significant inconsistencies in this joint occurrence at either modulus. The color-magnitude diagram for the nearby field also shows a faint, blue main-sequence turnoff and, in contrast to previous Magellanic Cloud field studies, the field lacks any evidence for the existence of a significant intermediate-age component. A new look at the chemical evolution of the Small Magellanic Cloud suggests that, unlike the Galaxy, where the rate of enrichment has been steady after the initial phase, the enrichment in the SMC remained small for a long interval before increasing rapidly sometime in the last 1-2x10^9^yr.
- ID:
- ivo://CDS.VizieR/J/A+A/351/526
- Title:
- NGC 2172 CCD BVI photometry
- Short Name:
- J/A+A/351/526
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new CCD photometry for the young LMC cluster NGC 2172, giving B, V, I magnitudes for more than 600 stars within 70" from the cluster center, down to -approximately- V=21mag. After correction for completeness and field stars contamination, we discuss the cluster HR diagram and the MS luminosity function in the light of current evolutionary theories and in connection with the problem of cluster age.
- ID:
- ivo://CDS.VizieR/J/AJ/133/44
- Title:
- NGC 346 HST VI photometry
- Short Name:
- J/AJ/133/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the quest to understand how star formation occurs and propagates in the low-metallicity environment of the Small Magellanic Cloud (SMC), we acquired deep F555W (~V) and F814W (~I) Hubble Space Telescope ACS images of the young and massive star-forming region NGC 346. These images and their photometric analysis provide us with a snapshot of the star formation history of the region. We find evidence for star formation extending from ~10Gyr in the past until ~150Myr in the field of the SMC. The youngest stellar population (~3+/-1Myr) is associated with the NGC 346 cluster. It includes a rich component of low-mass pre-main-sequence stars mainly concentrated in a number of subclusters spatially colocated with CO clumps previously detected by Rubio and coworkers. Within our analysis uncertainties, these subclusters appear coeval with each other.
