- ID:
- ivo://CDS.VizieR/J/ApJS/69/99
- Title:
- NGC 6334 centers of star formation JHK photometry
- Short Name:
- J/ApJS/69/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared observations of specific sites of high-mass star formation activity in the giant H II region/molecular cloud complex NGC 6334. The observations consist of high-spatial resolution broad-band imaging, chopping photometry, and moderate-resolution spectra. The imaging observations provide full spatial sampling of the stellar population over a significant area of the cloud to a limit of K=13.5mag and reveal many faint red sources around the sites of recent high-mass star formation. We show that most of these sources are associated with the NGC 6334 molecular cloud and are not Galactic field sources. In the majority of the regions the embedded sources are primarily reddened main-sequence stars of low and intermediate mass though in three of the 11 regions studied there is a high proportion of objects showing H-K excesses which are therefore probably pre main-sequence. We identify the red objects in FIR-I as belonging to a very young compact cluster of ~1pc spatial extent. In FIR-V an unexpectedly large number of bright red sources are detected which have CO absorption at 2.3{mu}m. The probability that these objects are Galactic field sources is very low and if they are giant stars associated with NGC 6334 their implied ages (>10^9^yr) are inconsistent with the many indicators of extreme youth in this region. We propose that they form a hitherto unrecognized population of high-luminosity pre-main-sequence objects. Two objects with similar characteristics are also found in images of an area of the NGC 6334 molecular cloud to the north of FIR-V (SH-1). In FIR-V we also find evidence that the molecular outflow from the already known high-mass protostar has triggered intermediate-mass star formation via interaction with the local interstellar medium. Mass functions have been derived for the embedded stellar aggregates under the assumption that all sources lie on the main sequence unless otherwise indicated. The effect of a population of pre-main-sequence objects on the derived mass function slopes is shown to be small. Embedded aggregates in NGC 6334 have stellar mass distributions similar to those found both in young visible clusters and in other embedded clusters. This suggests that the slope of the mass function is relatively insensitive to conditions in the star formation environment and that the solar neighborhood value applies to star formation regions on scales as small as 1pc and of ages less than 10^7^yr.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2998
- Title:
- NGC 6822 Cepheids JHKs light curves
- Short Name:
- J/MNRAS/421/2998
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent estimates of the Cepheid distance modulus of NGC 6822 differ by 0.18mag. To investigate this we present new multi-epoch JHKs photometry of classical Cepheids in the central region of NGC 6822 and show that there is a zero-point difference from earlier work. These data together with optical and mid-infrared observations from the literature are used to derive estimates of the distance modulus of NGC 6822. A best value of 23.40mag is adopted, based on a Large Magellanic Cloud (LMC) distance modulus of 18.50mag. The standard error of this quantity is ~0.05mag. We show that to derive consistent moduli from Cepheid observations at different wavelengths, it is necessary that the fiducial LMC period-luminosity relations at these wavelengths should refer to the same subsample of stars. Such a set is provided. A distance modulus based on RR Lyrae variables agrees with the Cepheid result.
- ID:
- ivo://CDS.VizieR/J/ApJ/586/814
- Title:
- NGC 4472 Chandra/HST study
- Short Name:
- J/ApJ/586/814
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a Chandra/Hubble Space Telescope (HST) study of the point sources of the Virgo Cluster giant elliptical galaxy NGC 4472. We identify 144 X-ray point sources outside the nuclear region, 72 of which are located within the HST fields. The optical data show 1102 sources, of which 829 have colors consistent with being globular clusters (with only four in the restricted central 10" region). Thirty matches are found between the two lists - these are likely to be low-mass X-ray binaries (LMXBs) associated with globular clusters, while ~42 of the X-ray sources have no optical counterparts to V<~25 and I<~24, indicating that they are likely to be predominantly LMXBs in the field star population with a small amount of possible contamination from background active galactic nuclei. Thus approximately 40% of the X-ray sources are in globular clusters and 4% of the globular clusters contain X-ray sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/600/716
- Title:
- NGC 5128 Chandra X-ray point sources
- Short Name:
- J/ApJ/600/716
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very Large Telescope images in BVI are used to identify the optical counterparts to bright Chandra X-ray points sources discovered by Kraft and coworkers (2001, Cat. <J/ApJ/560/675>). Of a total of 111 X-ray point sources with L_X_>2x10^36^erg/s present in a 56arcmin^2^ field centered on this galaxy, 58 have optical counterparts. On the basis of the sizes, optical magnitudes, and colors, 20 new globular cluster counterparts of X-ray sources are identified, and three are identified on the basis of their sizes. This brings the total number of globular cluster X-ray sources in this galaxy to 33 and establishes that 30% of the X-ray point sources in NGC 5128 are associated with globular clusters.
- ID:
- ivo://CDS.VizieR/J/A+AS/134/525
- Title:
- NGC 6611 compiled catalog
- Short Name:
- J/A+AS/134/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains data on stars in sky area of the open cluster NGC 6611. The catalogue is based on a new reduction of positions, proper motions, and photometric data whenever published in this region and includes among others, Hipparcos, AC/GSC and Tautenburg Schmidt plate observations. The basis of compiled catalogue is made of stars distributed over a circular area with radius of 22.8arcmin centered on the cluster NGC 6611 (Kharchenko and Schilbach, 1995AN....316...91K). To construct the compiled catalogue, we used also astrometric data published by Van Schewick (1962VeUSB..62....1V), Kamp (1974A&AS...16....1K), Tucholke et al. (1986A&AS...66..311T), Bastian and Roeser (1993, Cat. <I/193>), Roeser (1996, in "An updated GSC as the astrometric reference for minor planet observations", Kluwer Dordrecht, p. 481.), Hillenbrand et al. (1993, Cat. <J/AJ/106/1906>), and photometry published by Walker (1961ApJ...133..438W), Hoag et al. (1961PUSNO..17..343H), Hiltner and Morgan (1969AJ.....74.1152H), Sagar and Joshi (1979Ap&SS..66....3S), The et al (1990A&AS...82..319T), Hillenbrand et al. (1993, Cat. <J/AJ/106/1906>) as it described by Belikov et al. (1998, A&A, in press, this paper, 1999A&AS..134..525B). The catalogue contains 2185 stars up to the limiting magnitudes V=16.78mag. It includes equatorial (equinox 2000.0 and epoch 1990.77) and rectangular coordinates, absolute proper motions with respect to the Hipparcos proper motion system, photometric data (results of UBV, HJK photometry and color excess) and cluster membership probabilities. X - and Y - directions correspond to right ascension and declination directions. The rms errors of right ascension and declination are 0.008sec and 0.14arcsec, respectively. The individual rms errors of proper motions and V-magnitudes are given in the catalogue. The membership probabilities of the cluster stars belonging to the core and corona were determined using information both on spatial and proper motion distributions of stars in the field.
- ID:
- ivo://CDS.VizieR/J/A+A/320/405
- Title:
- NGC 5548 continuum light curve
- Short Name:
- J/A+A/320/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The variations of the [OIII]{lambda}5007 line profile in NGC 5548 are examine d from CCD spectra obtained at the Ohio State University and Crimean Astrophysic al Observatory in December 1988 - October 1994.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A16
- Title:
- NGC 6774 cool stars rotation periods
- Short Name:
- J/A+A/644/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gyrochronology allows the derivation of ages for cool main sequence stars based on their observed rotation periods and masses, or a suitable proxy thereof. It is increasingly well-explored for FGK stars, but requires further measurements for older ages and K-M-type stars. We study the 2.7Gyr-old open cluster Ruprecht 147 to compare it with the previously-studied, but far more distant, NGC 6819 cluster, and especially to measure cooler stars than was previously possible there. We constructed an inclusive list of 102 cluster members from prior work, including Gaia DR2, and for which light curves were also obtained during Campaign 7 of the Kepler/K2 space mission. We placed them in the cluster color-magnitude diagram and checked the related information against appropriate isochrones. The light curves were then corrected for data systematics using Principal Component Analysis on all observed K2 C07 stars and subsequently subjected to periodicity analysis. Periodic signals are found for 32 stars, 21 of which are considered to be both highly reliable and to represent single, or effectively single, Ru 147 stars. These stars cover the spectral types from late-F to mid-M stars, and they have periods ranging from 6d-33d, allowing for a comparison of Ruprecht 147 to both other open clusters and to models of rotational spindown. The derived rotation periods connect reasonably to, overlap with, and extend to lower masses the known rotation period distribution of the 2.5 Gyr-old cluster NGC 6819. The data confirm that cool stars lie on a single surface in rotation period-mass-age space, and they simultaneously challenge its commonly assumed shape. The shape at the low mass region of the color-period diagram at the age of Ru 147 favors a recently-proposed model which requires a third mass-dependent timescale in addition to the two timescales required by a former model, suggesting that a third physical process is required to model rotating stars effectively.
4378. NGC 6819 3D members
- ID:
- ivo://CDS.VizieR/J/other/RAA/15.2193
- Title:
- NGC 6819 3D members
- Short Name:
- J/other/RAA/15.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to obtain clean members of the open cluster NGC 6819, the proper motions and radial velocities of 1691 stars are used to construct a three-dimensional (3D) velocity space. Based on the DBSCAN clustering algorithm, 537 3D cluster members are obtained. From the 537 3D cluster members, the average radial velocity and absolute proper motion of the cluster are Vr=+2.30+/-0.04km/s and (PMRA, PMDE)=(-2.5+/-0.5, -4.3+/-0.5)mas/yr, respectively. The proper motions, radial velocities, spatial positions and color-magnitude diagram of the 537 3D members indicate that our membership determination is effective. Among the 537 3D cluster members, 15 red clump giants can be easily identified by eye and are used as reliable standard candles for the distance estimate of the cluster. The distance modulus of the cluster is determined to be (m-M)0=11.86+/-0.05mag (2355+/-54pc), which is quite consistent with published values. The uncertainty of our distance modulus is dominated by the intrinsic dispersion in the luminosities of red clump giants (~0.04mag).
- ID:
- ivo://CDS.VizieR/J/A+A/601/A56
- Title:
- NGC 6802 dwarf cluster members and non-members
- Short Name:
- J/A+A/601/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Milky Way open clusters are very diverse in terms of age, chemical composition, and kinematic properties. Intermediate-age and old open clusters are less common, and it is even harder to find them inside the solar Galactocentric radius, due to the high mortality rate and strong extinction inside this region. NGC 6802 is one of the inner disk open clusters (IOCs) observed by the $Gaia$-ESO survey (GES). This cluster is an important target for calibrating the abundances derived in the survey due to the kinematic and chemical homogeneity of the cluster members in open clusters. Using the measurements from $Gaia$-ESO internal data release 4 (iDR4), we identify 95 dwarf main-sequence stars as cluster members from the GIRAFFE target list, and 8 red giants as cluster members from the UVES target list. The dwarf cluster members have a median radial velocity of 13.6+/-1.9km/s, while the giant cluster members have a median radial velocity of 12.0+/-0.9km/s and a median [Fe/H] of 0.10+/-0.02dex. The color-magnitude diagram of these cluster members suggests an age of $0.9+/-0.1Gyr, with (m-M)_0_=11.4 and E(B-V)=0.86. We perform the first chemical abundance analysis of NGC 6802, including 27 element species. To gain a more general picture about IOCs, the measurements of NGC6802 are compared with those of other IOCs previously studied by GES, i.e., NGC 4815, Trumpler 20, NGC 6705, and Berkeley 81. NGC 6802 shows similar C, N, Na, and Al abundances as other IOCs. The abundance versus cluster turn-off mass for these elements in the five GES IOCs cannot firmly exclude any one of the competing nucleosynthetic models, including: standard models; models with rotation induced mixing and/or thermohaline mixing. The five GES IOCs, particularly NGC 6802, seem to have higher s-process element abundances than that of the inner disk field stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/4260
- Title:
- NGC1316 (Fornax A) g'r'i' photometry
- Short Name:
- J/MNRAS/461/4260
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents Gemini-gri' high-quality photometry for cluster candidates in the field of NGC 1316 (Fornax A) as part of a study that also includes GMOS spectroscopy. A preliminary discussion of the photometric data indicates the presence of four stellar cluster populations with distinctive features in terms of age, chemical abundance and spatial distribution. Two of them seem to be the usually old (metal poor and metal rich) populations typically found in elliptical galaxies. In turn, an intermediate-age (5 Gyr) globular cluster population is the dominant component of the sample (as reported by previous papers). We also find a younger cluster population with a tentative age of ~=1Gyr.
