- ID:
- ivo://CDS.VizieR/J/other/Ap/50.194
- Title:
- Groups of stars in NGC 1893
- Short Name:
- J/other/Ap/50.19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of 255 O-B9-A2, K-G stars and interstellar dust in the direction of the stellar cluster NGC 1893 is studied using V, B-V, and U-B photometric data. Sixteen groups of stars (associations) are discovered at various distances. The first group includes 9 stars of different spectral classes of later types in the Sun's neighborhood lying at a distance of 110pc. The next 3 groups, at distances of 420, 890, and 14300pc, are type B associations and the remaining twelve groups are OB associations. They are designated as Aur 0.11, Aur B 0.43, Aur B 0.89, Aur OB 1.4, Aur OB 2.6, AurOB 3.8, Aur OB 4.6, Aur OB 5.4, Aur OB 6.1, Aur OB 7.4, Aur OB 9.3, Aur OB11.6, Aur OB14.3, Aur OB 17.9, Aur OB 25.9, and Aur OB 31.3. For most of these stars the absorption lies within the range from 0.45m to 5.41m. Such high absorption may be caused by circumstellar absorption as well as by the diffuse nebula IC 410. The dusty matter is distributed non-uniformly in the Aur 0.11, Aur B 0.43, and Aur B 0.89 associations. There is no dust in the space between the associations. There is essentially no dust within the groups (associations) at distances greater than 0.9kpc (see Table 2).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/602/A69
- Title:
- Group sunspot number series since 1739
- Short Name:
- J/A+A/602/A69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The group sunspot number (GSN) series constitute the longest instrumental astronomical database providing information on solar activity. This database is a compilation of observations by many individual observers, and their inter-calibration has usually been performed using linear rescaling. There are multiple published series that show different long-term trends for solar activity. We aim at producing a GSN series, with a non-linear non-parametric calibration. The only underlying assumptions are that the differences between the various series are due to different acuity thresholds of the observers, and that the threshold of each observer remains constant throughout the observing period. We used a daisy chain process with backbone (BB) observers and calibrated all overlapping observers to them. We performed the calibration of each individual observer with a probability distribution function (PDF) matrix constructed considering all daily values for the overlapping period with the BB. The calibration of the BBs was carried out in a similar manner. The final series was constructed by merging different BB series. We modelled the propagation of errors straightforwardly with Monte Carlo simulations. A potential bias due to the selection of BBs was investigated and the effect was shown to lie within the 1{sigma} interval of the produced series. The exact selection of the reference period was shown to have a rather small effect on our calibration as well. The final series extends back to 1739 and includes data from 314 observers. This series suggests moderate activity during the 18th and 19th century, which is significantly lower than the high level of solar activity predicted by other recent reconstructions applying linear regressions. The new series provides a robust reconstruction, based on modern and non-parametric methods, of sunspot group numbers since 1739, and it confirms the existence of the modern grand maximum of solar activity in the second half of the 20th century.
- ID:
- ivo://CDS.VizieR/J/ApJ/826/71
- Title:
- Growth curves of CALIFA spiral galaxies
- Short Name:
- J/ApJ/826/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper aims to provide aperture corrections for emission lines in a sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey (CALIFA; Sanchez+, 2012A&A...538A...8S) database. In particular, we explore the behavior of the log([OIII]{lambda}5007/H{beta})/([NII]{lambda}6583/H{alpha}) (O3N2) and log[NII]{lambda}6583/H{alpha} (N2) flux ratios since they are closely connected to different empirical calibrations of the oxygen abundances in star-forming galaxies. We compute the median growth curves of H{alpha}, H{alpha}/H{beta}, O3N2, and N2 up to 2.5R_50_ and 1.5 disk Reff. These distances cover most of the optical spatial extent of the CALIFA galaxies. The growth curves simulate the effect of observing galaxies through apertures of varying radii. We split these growth curves by morphological types and stellar masses to check if there is any dependence on these properties. The median growth curve of the H{alpha} flux shows a monotonous increase with radius with no strong dependence on galaxy inclination, morphological type, and stellar mass. The median growth curve of the H{alpha}/H{beta} ratio monotonically decreases from the center toward larger radii, showing for small apertures a maximum value of ~10% larger than the integrated one. It does not show any dependence on inclination, morphological type, and stellar mass. The median growth curve of N2 shows a similar behavior, decreasing from the center toward larger radii. No strong dependence is seen on the inclination, morphological type, and stellar mass. Finally, the median growth curve of O3N2 increases monotonically with radius, and it does not show dependence on the inclination. However, at small radii it shows systematically higher values for galaxies of earlier morphological types and for high stellar mass galaxies. Applying our aperture corrections to a sample of galaxies from the SDSS survey at 0.02<=z<=0.3 shows that the average difference between fiber-based and aperture-corrected oxygen abundances, for different galaxy stellar mass and redshift ranges, reaches typically to ~11%, depending on the abundance calibration used. This average difference is found to be systematically biased, though still within the typical uncertainties of oxygen abundances derived from empirical calibrations. Caution must be exercised when using observations of galaxies for small radii (e.g., below 0.5 Reff) given the high dispersion shown around the median growth curves. Thus, the application of these median aperture corrections to derive abundances for individual galaxies is not recommended when their fluxes come from radii much smaller than either R_50_ or Reff.
- ID:
- ivo://CDS.VizieR/J/ApJ/336/780
- Title:
- gr photometry of NGC 5053 blue stragglers
- Short Name:
- J/ApJ/336/780
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Twenty-four blue straggler stars have been identified in the low central concentration globular cluster NGC 5053. New deep color-magnitude (C-M) diagrams to 23mag, constructed from photometry of over 6000 stars on 4-shooter CCD frames, show that they form a well-defined sequence in the C-M diagram, extending up to ~2.2mag brighter than the main-sequence turnoff point. The 12 most luminous blue stragglers are found to be significantly more centrally concentrated than the cluster subgiants with magnitudes in the same interval (a similar result is known for the blue stragglers in the globular cluster NGC 5466). Furthermore, they are also found to be more centrally concentrated than the 12 lower luminosity blue stragglers. Comparisons of the projected radial distributions of the bright and faint blue stragglers, with the radial distributions that are expected for stars of mass 0.8, 1.6, and 2.4M_{sun}_, (calculated using multimass King models) suggests that the brightest blue stragglers have an average mass of <M>=1.3+/0.3M_{sun}_, which is less than or comparable to twice the mean mass of a main-sequence turnoff star, and the lower luminosity blue stragglers have a mean mass similar to that of the main-sequence turnoff stars (i.e., M~0.8M_{sun}_). By fitting theoretical isochrones computed by Bell and VandenBerg to the observed main-sequence turnoff and subgiant branch regions of NGC 5053, a distance modulus of (m-M)_0_=16.05+/-0.14mag, and an age of 18+/-3Gyr are derived for NGC 5053. The main-sequence luminosity function shows no sign of "turning over" for stars brighter than M_g_~5mag. For a description of the uvgr photometric system, see e.g. <GCPD/38>
- ID:
- ivo://CDS.VizieR/J/A+A/566/A44
- Title:
- gr photometry of Sextans A and Sextans B
- Short Name:
- J/A+A/566/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of the stellar and HI structure of the dwarf irregular galaxies Sextans A and Sextans B, members of the NGC3109 association. We use newly obtained deep (r~26.5) and wide field g,r photometry to extend the Surface Brightness (SB) profiles of the two galaxies down to mu_V_~31.0mag/arcsec^2^. We find that both galaxies are significantly more extended than what previously traced with surface photometry, out to ~4kpc from their centers along their major axis. Older stars are found to have more extended distribution with respect to younger populations. We obtain the first estimate of the mean metallicity for the old stars in Sex B, from the color distribution of the Red Giant Branch, <[Fe/H]>=-1.6. The SB profiles show significant changes of slope and cannot be fitted with a single Sersic model. Both galaxies have HI discs as massive as their respective stellar components. In both cases the HI discs display solid-body rotation with maximum amplitude of ~50km/s (albeit with significant uncertainty due to the poorly constrained inclination), implying a dynamical mass ~10^9^~M_{sun}_, a mass-to-light ratio M/L_V_~25 and a dark to-barionic mass ratio of ~10. The distribution of the stellar components is more extended than the gaseous disc in both galaxies. We find that the main, approximately round-shaped, stellar body of Sex A is surrounded by an elongated low-SB stellar halo that can be interpreted as a tidal tail, similar to that found in another member of the same association (Antlia). We discuss these, as well as other evidences of tidal disturbance, in the framework of a past passage of the NGC3109 association close to the Milky Way, that has been hypothesized by several authors and is also supported by the recently discovered filamentary configuration of the association itself
- ID:
- ivo://CDS.VizieR/J/ApJ/803/63
- Title:
- gr photometry of stars in Kim 2
- Short Name:
- J/ApJ/803/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a new, low-luminosity star cluster in the outer halo of the Milky Way. High-quality gr photometry is presented, from which a color-magnitude diagram is constructed, and estimates of age, [Fe/H], [{alpha}/Fe], and distance are derived. The star cluster, which we designate as Kim 2, lies at a heliocentric distance of ~105kpc. With a half-light radius of ~12.8pc and ellipticity of {epsilon}~0.12, it shares the properties of outer halo globular clusters, except for at higher metallicity ([Fe/H]~-1.0) and lower luminosity (M_v_~-1.5). These parameters are similar to those for the globular cluster AM 4, which is considered to be associated with the Sagittarius dwarf spheroidal galaxy. We find evidence of dynamical mass segregation and the presence of extra-tidal stars that suggests that Kim 2 is most likely a star cluster. Spectroscopic observations for radial-velocity membership and chemical abundance measurements are needed to further understand the nature of the object.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/1587
- Title:
- GRS/BGPS sources in Galactic Plane
- Short Name:
- J/MNRAS/431/1587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The line of sight through the Galactic plane between longitudes l=37.83{deg} and 42.50{deg} allows for the separation of Galactic Ring Survey molecular clouds into those that fall within the spiral arms and those located in the interarm regions. By matching these clouds in both position and velocity with dense clumps detected in the mm continuum by the Bolocam Galactic Plane Survey, we are able to look for changes in the clump formation efficiency (CFE), the ratio of clump to cloud mass, with Galactic environment. We find no evidence of any difference in the CFE between the interarm and spiral-arm regions along this line of sight. This is further evidence that, outside the Galactic Centre region, the large-scale structures of the Galaxy play little part in changing the dense, potentially star-forming structures within molecular clouds.
7678. GRS Gamma-Ray Bursts
- ID:
- ivo://nasa.heasarc/smmgrs
- Title:
- GRS Gamma-Ray Bursts
- Short Name:
- SMMGRS
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Gamma-Ray Spectrometer (GRS) was one of two instruments on the Solar Maximum Mission (SMM) which independently monitored cosmic gamma-ray bursts from SMM's launch in February 1980 until the end of the mission in 1989. The GRS was designed for investigation of the gamma-ray spectrum of solar flares (Forrest, D.J. et al. 1980, Sol. Phys., 65, 15). The main detector was an array of seven gain-controlled 7.6 cm diameter X 7.6 cm thick NaI(Tl) detectors. A complete spectrum was obtained every 16.38 seconds in the energy range 0.3-9 MeV. The number of counts in three energy windows covering the 4.2-6.4 MeV range was read out every 2.048 seconds. In addition, the number of counts in an approximately 50 keV wide window near 300 keV was read out every 64 milliseconds. The spectrometer was shielded by a 2.5 cm thick CsI(Na) annulus and a 25 cm diameter X 7.6 cm thick CsI(Na) back detector. The shield elements defined a field of view of approximately 135 degrees (FWHM) in the solar direction. The CsI back detector and the seven NaI detectors together provided a high-energy spectrometer with approximately 100 cm<sup>2</sup> effective area and four energy channels from 10 to 100 MeV. The number of counts in those high-energy channels was read out every 2.048 seconds. The experiment was complemented by two 8 cm<sup>2</sup> X 0.6 cm thick NaI(Tl) detectors which measured the X-ray portion of the spectrum every 1.024 seconds in the range from 13 keV to 182 keV. This database table was created by the HEASARC in the early 1990s based on tables supplied by the SMM Project and was subsequently revised in February 2002. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/513/A21
- Title:
- GRS 1915+105 timing analysis
- Short Name:
- J/A+A/513/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- GRS 1915+105 was observed by BeppoSAX for about 10 days in October 2000. For about 80% of the time, the source was in the variability class rho, characterised by a series of recurrent bursts. We describe the results of the timing analysis performed on the MECS (1.6-10keV) and PDS (15-100keV) data. The X-ray count rate from GRS 1915+105 showed an increasing trend with different characteristics in the various energy bands: in the bands (1.6-3keV) and (15-100keV), it was nearly stable in the first part of the pointing and increased in a rather short time by about 20%, while in the energy range (3-10keV) the increase had a smoother trend.
7680. GR Tau BV light curves
- ID:
- ivo://CDS.VizieR/J/A+A/395/587
- Title:
- GR Tau BV light curves
- Short Name:
- J/A+A/395/587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric observations of the eclipsing binary GR Tau made in 1985, 1993, 1998, 2000 and 2001.