- ID:
- ivo://CDS.VizieR/J/PASP/121/1180
- Title:
- Color panorama image of the Milky Way
- Short Name:
- J/PASP/121/1180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This article describes the assembly of an optical (RGB) all-sky mosaic image with an image scale of 36"/pix, a limiting magnitude of approximately 14mag, and an 18 bit dynamic range. Using a portable low-cost CCD camera system, 70 fields (each covering 40{deg}x27{deg}) were imaged over a time span of 22 months from dark-sky locations in South Africa, Texas, and Michigan. The fields were photometrically calibrated against standard catalog stars. Using sky background data from the Pioneer 10 and 11 space probes, gradients resulting from artificial light pollution, airglow, and zodiacal light were eliminated, while the large-scale galactic and extragalactic background resulting from unresolved sources was preserved. The 648 megapixel image is a valuable educational tool, being able to fully utilize the resolution and dynamic range of modern full-dome planetarium projection systems.
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- ID:
- ivo://CDS.VizieR/J/A+A/583/A73
- Title:
- Color-period diagram for M48 (NGC2548)
- Short Name:
- J/A+A/583/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation periods are increasingly being used to derive ages for cool single field stars. Such ages are based on an empirical understanding of how cool stars spin down, acquired by constructing color-period diagrams (CPDs) for a series of open clusters. Our main aims here are to construct a CPD for M48, to compare this with other clusters of similar age to check for consistency, and to derive a rotational age for M48 using gyrochronology. We monitored M48 photometrically for over 2months with AIP's STELLA.I 1.2m telescope and the WiFSIP 4K imager in Tenerife. Light curves with 3mmag precision for bright (V~14mag) stars were produced and then analysed to provide rotation periods. A cluster CPD has then been constructed. We report 62 rotation periods for cool stars in M48. The CPD displays a clear slow/I-sequence of rotating stars, similar to those seen in the 625Myr-old Hyades and 590Myr-old Praesepe clusters, and below both, confirming that M48 is younger. A similar comparison with the 250Myr-old M34 cluster shows that M48 is older and does not possess any fast/C-sequence G or early K stars like those in M34, although relatively fast rotators do seem to be present among the late-K and M stars. A more detailed comparison of the CPD with rotational evolution models shows that the cluster stars have a mean age of 450Myr, and its (rotating) stars can be individually dated to +/-117Myr (26%). Much of this uncertainty stems from intrinsic astrophysical spread in initial periods, and almost all stars are consistent with a single age of 450Myr. The gyro-age of M48 as a whole is 450+/-50Myr, in agreement with the previously determined isochrone age of 400+/-100Myr.
- ID:
- ivo://CDS.VizieR/II/84
- Title:
- 13-color photometry of 1380 bright stars
- Short Name:
- II/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue contains observations of essentially all stars brighter than fifth visual magnitude north of declination -20 degrees and brighter than fourth visual magnitude south of declination -20 degrees, in the 13-color medium-narrow-band photometric system.
- ID:
- ivo://CDS.VizieR/J/A+A/507/283
- Title:
- Colors and extinction across the disk of M31
- Short Name:
- J/A+A/507/283
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a study of the dust properties in M31. We analyzed Spitzer Space Telescope, GALEX, and SDSS images constraining some basic properties of the dust in M31: (i) the mass of the dust; (ii) the mean intensity of the radiation field heating the dust; (iii) the abundance of Polycyclic Aromatic Hydrocarbon (PAH) particles. We also studied which stellar populations are most likely responsible for the dust heating in M31 analyzing optical and infrared colors and comparing our observations with models which account for the age-dependent dust heating. We found that in most of the regions analyzed stars at least a few Gyr old are the major dust heaters. We then derived the extinction map across the disk of M31.
- ID:
- ivo://CDS.VizieR/J/AJ/139/1808
- Title:
- Colors and kinematics of SDSS L dwarfs
- Short Name:
- J/AJ/139/1808
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 484 L dwarfs, 210 of which are newly discovered from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic database. We combine this sample with known L dwarfs to investigate their izJHKS colors. We present photometric distance relations based on i-z and i-J colors and derive distances to our L dwarf sample. We combine the distances with SDSS/2MASS proper motions in order to examine the tangential velocities.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/369
- Title:
- Colour and spectral index from the SLUGGS survey
- Short Name:
- J/MNRAS/446/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, we stack 1137 Keck DEIMOS (Deep Imaging Multi-Object Spectrograph) spectra of globular clusters from 10 galaxies to study their stellar populations in detail. The stacked spectra have median signal-to-noise ratios of ~90 {AA}^-1^. Besides the calcium triplet, we study weaker sodium, magnesium, titanium and iron lines as well as the H{alpha} and higher order Paschen hydrogen lines. In general, the stacked spectra are consistent with old ages and a Milky Way-like initial mass function. However, we see different metal line index strengths at fixed colour and magnitude, and differences in the calcium triplet-colour relation from galaxy to galaxy. We interpret this as strong evidence for variations in the globular cluster colour-metallicity relation between galaxies. Two possible explanations for the colour-metallicity relation variations are that the average ages of globular clusters vary from galaxy to galaxy or that the average abundances of light elements (i.e. He, C, N and O) differ between galaxies. Stacking spectra by magnitude, we see that the colours become redder and metal line indices stronger with brighter magnitudes. These trends are consistent with the previously reported `blue tilts' being mass-metallicity relations.
- ID:
- ivo://CDS.VizieR/J/AN/333/60
- Title:
- Colour indices of selected OB stars
- Short Name:
- J/AN/333/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have applied the method of investigating extinction curves using statistically meaningful samples that was proposed by us 25 years ago. The extensive data sets of the ANS (Astronomical Netherlands Satellite) and 2MASS (Two Micron All Sky Survey) were used, together with UBV photometry to create average extinction curves for samples of OB stars. Our results demonstrate that in the vast majority of cases the extinction curves are very close to the mean galactic extinction curve. Only a few objects were found to be obviously discrepant from the average. The latter phenomenon may be related to nitrogen chemistry in translucent interstellar clouds.
- ID:
- ivo://CDS.VizieR/J/A+AS/102/397
- Title:
- Colour magnitude diagram of M13
- Short Name:
- J/A+AS/102/397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two overlapping regions of M13 were observed on April 24, 1989 at the Loiano Observatory with a CDCD camera. A Colour-Magnitude diagram down to the main sequence was derived, as a preliminary search for the blue Horizontal Branch stars in this cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/582/668
- Title:
- Colours and H{alpha} in galaxy pairs
- Short Name:
- J/ApJ/582/668
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy-galaxy interactions rearrange the baryons in galaxies and trigger substantial star formation; the aggregate effects of these interactions on the evolutionary histories of galaxies in the universe are poorly understood. We combine B- and R-band photometry and optical spectroscopy to estimate the strengths and timescales of bursts of triggered star formation in the centers of 190 galaxies in pairs and compact groups. Based on an analysis of the measured colors and EW(H{alpha}), we characterize the preexisting and triggered populations separately. The best-fitting burst scenarios assume stronger reddening corrections for line emission than for the continuum and continuous star formation lasting for >~100Myr. The most realistic scenarios require an initial mass function that is deficient in the highest mass stars. The color of the preexisting stellar population is the most significant source of uncertainty. Triggered star formation contributes substantially (probably >~50%) to the R-band flux in the central regions of several galaxies; tidal tails do not necessarily accompany this star formation. Many of the galaxies in our sample have bluer centers than outskirts, suggesting that pre- or nonmerger interactions may lead to evolution along the Hubble sequence. These objects would appear blue and compact at higher redshifts; the older, redder outskirts of the disks would be difficult to detect. Our data indicate that galaxies with larger separations on the sky contain weaker, and probably older, bursts of star formation on average. However, confirmation of these trends requires further constraints on the colors of the older stellar populations and on the reddening for individual galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/819
- Title:
- Colours and HI line observations in Virgo
- Short Name:
- J/MNRAS/357/819
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to investigate the nature of dwarf low surface brightness (LSB) galaxies we have undertaken a deep B- and I-band CCD survey of a 14-deg^2^ strip in the Virgo Cluster and applied a Fourier convolution technique to explore its dwarf galaxy population down to a central surface brightness of ~26Bmag/arcsec^2^ and a total absolute B magnitude of ~-10. In this paper we carry out an analysis of their morphology, (B-I) colours and atomic hydrogen content.