- ID:
- ivo://CDS.VizieR/J/A+A/430/941
- Title:
- Star formation region NGC 6530
- Short Name:
- J/A+A/430/941
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present astrometry and BVI photometry, down to V~22, of the very young open cluster NGC 6530, obtained from observations taken with the Wide Field Imager camera at the MPG/ESO 2.2m Telescope. We have positionally matched our optical catalog with the list of X-ray sources found in a Chandra-ACIS observation, finding a total of 828 common stars, 90% of which are pre-main sequence stars in NGC 6530.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/138/1203
- Title:
- Star formation regions in nearby dwarf galaxies
- Short Name:
- J/AJ/138/1203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare star formation in the inner and outer disks of 11 dwarf irregular galaxies (dIm) within 3.6Mpc. The regions are identified on Galaxy Evolution Explorer near-UV images, and modeled with UV, optical, and near-IR colors to determine masses and ages. A few galaxies have made 10^5^-10^6^M_{sun}_ complexes in a starburst phase, while others have not formed clusters in the last 50Myr. The maximum region mass correlates with the number of regions as expected from the size-of-sample effect. We find no radial gradients in region masses and ages, even beyond the realm of H{alpha} emission, although there is an exponential decrease in the luminosity density and number density of the regions with radius. H{alpha} is apparently lacking in the outer parts only because nebular emission around massive stars is too faint to see. The outermost regions for the five galaxies with HI data formed at average gas surface densities of 1.9-5.9M_{sun}/pc^2^.
- ID:
- ivo://CDS.VizieR/J/AZh/88/342
- Title:
- Star-forming regions in NGC 5585 and IC 1525
- Short Name:
- J/AZh/88/342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use UBVRI CCD photometry to study star-forming regions (SFRs) in the galaxies NGC 5585 and IC 1525. The observations were acquired with the 1.5-m telescope of the Mt. Maidanak Observatory of the Astronomical Institute of the Uzbek Academy of Sciences (Uzbekistan), with seeing of 0.8"-1.8". We identified 47 SFRs in NGC 5585 and 16 SFRs in IC 1525.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/88
- Title:
- Star-forming regions in NGC 6822 from UV data
- Short Name:
- J/ApJ/730/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We characterize the star formation in the low-metallicity galaxy NGC 6822 over the past few hundred million years, using GALEX far-UV (FUV, 1344-1786{AA}) and near-UV (NUV, 1771-2831{AA}) imaging, and ground-based H{alpha} imaging. From the GALEX FUV image, we define 77 star-forming (SF) regions with area >860pc^2^, and surface brightness <~26.8 mag (AB) arcsec^-2^, within 0.2{deg} (1.7kpc) of the center of the galaxy. We estimate the extinction by interstellar dust in each SF region from resolved photometry of the hot stars it contains: E(B-V) ranges from the minimum foreground value of 0.22mag up to 0.66+/-0.21mag. The integrated FUV and NUV photometry, compared with stellar population models, yields ages of the SF complexes up to a few hundred Myr, and masses from 2x10^2^M_{sun}_ to 1.5x10^6^M_{sun}_. The derived ages and masses strongly depend on the assumed type of interstellar selective extinction, which we find to vary across the galaxy. The total mass of the FUV-defined SF regions translates into an average star formation rate (SFR) of 1.4x10^-2^M_{sun}_/yr over the past 100Myr, and SFR=1.0x10^-2^M_{sun}_/yr in the most recent 10Myr. The latter is in agreement with the value that we derive from the H{alpha} luminosity, SFR=0.008M_{sun}_/yr. The SFR in the most recent epoch becomes higher if we add the SFR=0.02M_{sun}_/yr inferred from far-IR measurements, which trace star formation still embedded in dust (age <~ a few Myr).
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/3393
- Title:
- Stars and globulars in NGC4494
- Short Name:
- J/MNRAS/415/3393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive analysis of the spatial, kinematic and chemical properties of stars and globular clusters (GCs) in the 'ordinary' elliptical galaxy NGC 4494 using data from the Keck and Subaru telescopes. We derive galaxy surface brightness and colour profiles out to large galactocentric radii. We compare the latter to metallicities derived using the near-infrared Calcium Triplet. We obtain stellar kinematics out to ~3.5 effective radii.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A61
- Title:
- Stars associated to Eagle Nebula (M16=NGC6611)
- Short Name:
- J/A+A/521/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive star-forming regions are characterized by intense ionizing fluxes, strong stellar winds and, occasionally, supernovae explosions, all of which have important effects on the surrounding media, on the star-formation process and on the evolution of young stars and their circumstellar disks. We present a multiband study of the massive young cluster NGC 6611 and its parental cloud (the Eagle Nebula) with the aim of studying how OB stars affect the early stellar evolution and the formation of other stars. We search for evidence of triggering of star formation by the massive stars inside NGC 6611 on a large spatial scale (~10 parsec) and ongoing disk photoevaporation in NGC 6611 and how its efficiency depends on the mass of the central stars.
- ID:
- ivo://CDS.VizieR/J/AJ/130/2677
- Title:
- Stars in the Carina dSph galaxy field
- Short Name:
- J/AJ/130/2677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The question of the existence of active and prominent tidal disruption around various Galactic dwarf spheroidal (dSph) galaxies remains controversial. That debate often centers on the nature (bound vs. unbound) of extended populations of stars claimed to lie outside the bounds of single King profiles fitted to the density distributions of dSph centers. However, the more fundamental issue of the very existence of the previously reported extended populations is still contentious. We present a critical evaluation of the debate centering on one particular dSph, Carina, for which claims both for and against the existence of stars beyond the King limiting radius have been made.
- ID:
- ivo://CDS.VizieR/J/A+A/272/235
- Title:
- Stars in the dark cloud L1251
- Short Name:
- J/A+A/272/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance of the dark cloud L1251 was estimated from observations made at the Konkoly Observatory between 1985 and 1991. The spectral classification and the H{alpha} emission features were measured on objective-prism plates taken with the 60/80/180 Schmidt telescope; the photometry was derived from observations made on photographic plates with emulsion-filter combinations giving magnitudes in the Johnson photometric system. The distance of the cloud was found to be 300+/-50pc.
- ID:
- ivo://CDS.VizieR/J/AJ/115/2397
- Title:
- Stars in the solar region
- Short Name:
- J/AJ/115/2397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several samples of nearby stars with the most accurate astrometric and photometric parameters are searched for clues to their evolutionary history. The main samples are (1) the main-sequence stars with b-y between 0.29 and 0.59mag (F3 to K1) in the Yale parallax catalog, (2) a group of high-velocity subgiants studied spectroscopically by Ryan & Lambert (1995AJ....109.2068R), and (3) high-velocity main-sequence stars in the extensive investigation by Norris, Bessel, & Pickles (1985ApJS...58..463N). The major conclusions are as follows: (1) The oldest stars (halo), t>=10-12Gyr, have V-velocities (in the direction of Galactic rotation and referred to the Sun) in the range from about -50 to -800km/s and have a heavy-element abundance [Fe/H] of less than about -0.8dex. The age range of these objects depends on our knowledge of globular cluster ages, but if age is correlated with V-velocity, the youngest may be M22 and M28 (V~-50km/s) and the oldest NGC 3201 (V~-500km/s) and assorted field stars. (2) The old disk population covers the large age range from about 2Gyr (Hyades, NGC 752) to 10 or 12Gyr (Arcturus group, 47 Tuc), but the lag (V) velocity is restricted to less than about 120km/s and [Fe/H]>=-0.8 or -0.9dex. The [Fe/H]~-0.8dex division between halo and old disk, near t~10-12Gyr, is marked by a change in the character of the CN index (Cm) and of the blanketing parameter K of the DDO photometry. (3) The young disk population, t<2Gyr, is confined exclusively to a well-defined area of the (U, V) velocity plane. The age separating young and old disk stars is also that separating giant evolution of the Hyades (near main-sequence luminosity) and M67 (degenerate helium cores and a large luminosity rise) kinds. The two disk populations are also separated by such indexes as the g-index of Geveva photometry. There appears to be no obvious need to invoke exogeneous influences to understand the motion and heavy-element abundance distributions of the best-observed stars near the Sun. Individual stars of special interest include the parallax star HD 55575, which may be an equal-component binary, and the high-velocity star HD 220127, with a well-determined space velocity near 1000km/s.
- ID:
- ivo://CDS.VizieR/J/AJ/155/161
- Title:
- Stars nearby Robo-AO Kepler planetary candidates
- Short Name:
- J/AJ/155/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the overall statistical results from the Robo-AO Kepler planetary candidate survey, comprising of 3857 high-angular resolution observations of planetary candidate systems with Robo-AO, an automated laser adaptive optics system. These observations reveal previously unknown nearby stars blended with the planetary candidate host stars that alter the derived planetary radii or may be the source of an astrophysical false positive transit signal. In the first three papers in the survey, we detected 440 nearby stars around 3313 planetary candidate host stars. In this paper, we present observations of 532 planetary candidate host stars, detecting 94 companions around 88 stars; 84 of these companions have not previously been observed in high resolution. We also report 50 more-widely separated companions near 715 targets previously observed by Robo-AO. We derive corrected planetary radius estimates for the 814 planetary candidates in systems with a detected nearby star. If planetary candidates are equally likely to orbit the primary or secondary star, the radius estimates for planetary candidates in systems with likely bound nearby stars increase by a factor of 1.54, on average. We find that 35 previously believed rocky planet candidates are likely not rocky due to the presence of nearby stars. From the combined data sets from the complete Robo-AO KOI survey, we find that 14.5+/-0.5% of planetary candidate hosts have a nearby star with 4", while 1.2% have two nearby stars, and 0.08% have three. We find that 16% of Earth-sized, 13% of Neptune-sized, 14% of Saturn-sized, and 19% of Jupiter-sized planet candidates have detected nearby stars.
