- ID:
- ivo://CDS.VizieR/J/A+A/337/125
- Title:
- NGC 1750 & 1758 membership probabilities
- Short Name:
- J/A+A/337/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cluster-field segregation and determination of physical parameters of the open clusters NGC 1750 and NGC 1758 were performed from CCD and photographic photometric and astrometric surveys previously published by the authors. Membership probabilities were computed to a brightness limit of R=15mag through a non-standard method in a fully non-parametric approach, using proper motions, positions and photometry. This study allowed several parameters for NGC 1750 and NGC 1758 to be determined, including position, size, density profile, absorption, distance, age, luminosity function and mass. The common colour excess of both clusters is E(B-V)=0.34mag. NGC 1750 is slightly younger (log(t)=8.3), closer (V-M_v_=9.0mag) and less concentrated than NGC 1758 (log(t)=8.60 and V-M_v_=9.4mag). We also conclude that NGC 1746 is an erroneous assignation (not corresponding to any real open cluster), and that NGC 1750 and NGC 1758 are overlapping clusters, but they do not constitute a gravitationally bounded system.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/420/1333
- Title:
- NGC 5024 (M53) RR Lyrae VI light curves
- Short Name:
- J/MNRAS/420/1333
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of amplitude and phase modulations typical of the Blazhko effect in 22 RRc and nine RRab type RR Lyrae stars in NGC 5024 (M53). This brings the confirmed Blazhko variables in this cluster to 23 RRc and 11 RRab stars, which represent 66 and 37 per cent of the total population of RRc and RRab stars in the cluster, respectively, making NGC 5024 the globular cluster with the largest presently known population of Blazhko RRc stars. We place a lower limit of 52 per cent on the overall incidence rate of the Blazhko effect among the RR Lyrae population in this cluster. New data have allowed us to refine the pulsation periods. The limitations imposed by the time span and sampling of our data prevent reliable estimations of the modulation periods. The amplitudes of the modulations range between 0.02 and 0.39mag. The RRab and RRc are neatly separated in the colour-magnitude diagram, and the RRc Blazhko variables are on average redder than their stable counterparts; these two facts may support the hypothesis that the horizontal branch (HB) evolution in this cluster is towards the red and that the Blazhko modulations in the RRc stars are connected with the pulsation mode switch.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/2901
- Title:
- NGC 6752 multiwavelength survey
- Short Name:
- J/MNRAS/423/2901
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a multiwavelength (far-ultraviolet to I band) survey of the stellar populations of the globular cluster NGC 6752, using Space Telescope Imaging Spectrograph (STIS, FUV, 2001/03/01), Advanced Camera for Surveys (ACS, VI on 2006/06/24) and Wide Field Camera 3 (WFC3, NUV on 2010/07/31, 2010/08/07 and 2010/08/21, and UB on 2010/05/1-5) on board the Hubble Space Telescope. We have confirmed that two previously identified cataclysmic variable (CV) candidates are, in fact, dwarf novae which underwent outbursts during our observations. We have also identified previously unknown optical counterparts to two X-ray sources.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A12
- Title:
- NGC253 near-infrared H_2_ emission
- Short Name:
- J/A+A/550/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Because of its large angular size and proximity to the Milky Way, NGC 253, an archetypal starburst galaxy, provides an excellent laboratory to study the intricacies of this intense episode of star formation. We aim to characterize the excitation mechanisms driving the emission in NGC 253. Specifically we aim to distinguish between shock excitation and ultraviolet (UV) excitation as the dominant driving mechanism, using Br{gamma}, H_2_ and [FeII] as diagnostic emission line tracers.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/239
- Title:
- NGC 1750 + NGC 1758 BVR photometry
- Short Name:
- J/A+AS/131/239
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photographic astrometric and photometric catalogue. Table 6 contains (x,y) positions, (mu_x, mu_y) relative proper motions and BVR photographic photometry. Notes give cross-identifications with other catalogues. Table 11 contains equatorial positions (alpha, delta) and absolute proper motions (mu_alpha cos delta, mu_delta) in FK5 and ICRS reference systems.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/293
- Title:
- NGC 2366, NGC 2403 & NGC 4236 HK' photometry
- Short Name:
- J/A+AS/125/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near Infrared H and K' surface photometry of the three nearby galaxies NGC 2366, NGC 2403 and NGC 4236, used as local calibrators of the Tully-Fisher relation, was obtained using the 256^2^ NICMOS3 IR array MAGIC attached to the 2.2 m telescope of Calar Alto. The present measurements are compared with the aperture photometry available in the literature. Surface brightness profiles and integrated magnitudes are given.
- ID:
- ivo://CDS.VizieR/J/AJ/115/130
- Title:
- NGC 925 & NGC 1637 supergiants VRI CCD photometry
- Short Name:
- J/AJ/115/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V, R, and I CCD images obtained with the Canada-France-Hawaii Telescope are used to investigate the bright stellar content of the barred spiral galaxies NGC 925 and NGC 1637. Not counting objects located in H II regions, we detect 295 supergiants in NGC 925 and 266 in NGC 1637. Comparisons with theoretical isochrones indicate that massive star formation in NGC 925 has been ongoing for at least a few tens of millions of years. Most of the supergiants in NGC 925 are younger than 20Myr and have masses between 10 and 60M_{sun}_. The majority of supergiants in NGC 1637 appear to be younger than 40Myr and have initial masses between 8 and 60 M_{sun}_. The luminosity functions of supergiants in both galaxies follow power laws with exponents d(logn)/d(logV)=0.50+/-0.05 for NGC 925 and 0.62+/-0.04 for NGC 1637. These values are shallower than what is seen in most spiral galaxies, although there are some exceptions. Archival Hubble Space Telescope images of NGC 925 are used to assess the effects of blending on our photometric measurements. We conclude that crowding could cause a flattening of the luminosity function and bias the brightnesses of the most luminous stars. The brightest red supergiants are used to estimate the distance moduli of these galaxies. After applying corrections for blending, we find that {mu}_0_=29.67 for NGC 925 and {mu}_0_=29.47 for NGC 1637, corresponding to linear distances of 8.6^+1.1^_-1.0_ and 7.8^+1.0^_-0.9_Mpc, respectively. The distance computed for NGC 925 is in good agreement with that recently derived from Cepheids.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A56
- Title:
- NGC 346/N66 JHKs photometry
- Short Name:
- J/A+A/515/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The emission nebula N66 is the brightest HII Region in the Small Magellanic Cloud (SMC), with the stellar association NGC 346 located in its center. The youthfulness of the region NGC 346/N66 is well documented by studies of the gas and dust emission, and the detection in the optical of a rich sample of pre-main sequence (PMS) stars, and in the mid- and far-IR of Young Stellar Objects (YSOs). However, there is a lack of a comprehensive study of this region in the near-IR that will bridge the previous surveys. We perform a photometric analysis on deep, seeing-limited near-IR VLT images of the region NGC 346/N66 and a nearby control field of the SMC in order to locate the centers of active high- and intermediate-mass star formation through the identification of near-IR bright objects as candidate stellar sources under formation. We use archived imaging data obtained with the high-resolution camera ISAAC at VLT of NGC 346/N66 and we construct the near-IR color-magnitude (CMD) and color-color diagrams (C-CD) of all detected sources. We investigate the nature of all stellar populations in the observed CMDs, and we identify all stellar sources that show significant near-IR excess emission in the observed C-CD. We select, thus, the best candidates for being young stellar sources. Results. Based on their near-IR colors we select 263 candidate young stellar sources. This sample comprises a variety of objects such as intermediate-mass PMS and Herbig Ae/Be stars and possibly massive YSOs, providing original near-IR colors for them. The spatial distribution of the selected candidate sources shows that they are located along the dusty filamentary structures of N66 seen in mid- and far-IR dust emission and agrees very well with that of previously detected candidate YSOs and PMS stars.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A77
- Title:
- NGC 1893 optical and NIR photometry
- Short Name:
- J/A+A/527/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Different environmental conditions can play a crucial role in determining final products of the star formation process and in this context, less favorable activities of star formation are expected in the external regions of our Galaxy. We studied the properties of the young open cluster NGC 1893 located about 12kpc from the galactic center, to investigate how different physical conditions can affect the process of star formation. By adopting a multiwavelength approach, we compiled a catalog extending from X-rays to NIR data to derive the cluster membership. In addition, optical and NIR photometric properties are used to evaluate the cluster parameters. We find 415 diskless candidate members plus 1061 young stellar objects with a circumstellar disk or class II candidate members, 125 of which are also H{alpha} emitters. Considering the diskless candidate members, we find that the cluster distance is 3.6+/-0.2kpc and the mean interstellar reddening is E(B-V)=0.6+/-0.1 with evidence of differential reddening in the whole surveyed region. NGC 1893 contains a conspicuous population of pre-main sequence stars together with the well studied main sequence cluster population; we found a disk fraction of about 70% similar to that found in clusters of similar age in the solar neighbor and then, despite expected unfavorable conditions for star formation, we conclude that very rich young clusters can form also in the outer regions of our Galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/2813
- Title:
- NGC 2282 photometry of variable stars
- Short Name:
- J/MNRAS/476/2813
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report here CCD I-band time series photometry of a young (2-5Myr) cluster NGC 2282, in order to identify and understand the variability of pre-main-sequence (PMS) stars. The I-band photometry, down to ~20.5mag, enables us to probe the variability towards the lower mass end (~0.1M_{sun}_) of PMS stars. From the light curves of 1627 stars, we identified 62 new photometric variable candidates. Their association with the region was established from H{alpha} emission and infrared (IR) excess. Among 62 variables, 30 young variables exhibit H{alpha} emission, near-IR (NIR)/mid-IR (MIR) excess or both and are candidate members of the cluster. Out of 62 variables, 41 are periodic variables, with a rotation rate ranging from 0.2-7d. The period distribution exhibits a median period at ~1d, as in many young clusters (e.g. NGC 2264, ONC, etc.), but it follows a unimodal distribution, unlike others that have bimodality, with slow rotators peaking at ~6-8d. To investigate the rotation-disc and variability-disc connection, we derived the NIR excess from {Delta}(I-K) and the MIR excess from Spitzer [3.6]-[4.5]um data. No conclusive evidence of slow rotation with the presence of discs around stars and fast rotation for discless stars is obtained from our periodic variables. A clear increasing trend of the variability amplitude with IR excess is found for all variables.
