The subject is the mass of the three dominant, equilibrium cosmological objects: the irregular galaxy (dwarf), the regular galaxy (Hubble’s “tuning fork”), and the galactic cluster. The standard ΛCDM theory and a ...The subject is the mass of the three dominant, equilibrium cosmological objects: the irregular galaxy (dwarf), the regular galaxy (Hubble’s “tuning fork”), and the galactic cluster. The standard ΛCDM theory and a DEH offer contrasting views on the origin of these masses. The latter suggests that they are relics of the early universe.展开更多
Galactic open clusters （OCs） that survive the early gas-expulsion phase are gradually de- stroyed over time by the action of disruptive dynamical processes. Their final evolutionary stages are characterized by a poo...Galactic open clusters （OCs） that survive the early gas-expulsion phase are gradually de- stroyed over time by the action of disruptive dynamical processes. Their final evolutionary stages are characterized by a poorly populated concentration of stars called an open cluster remnant （OCR）. This study is devoted to assessing the real physical nature of the OCR candidate NGC 7193. GMOS/Gemini spectroscopy of 53 stars in the inner target region were obtained to derive radial velocities and at- mospheric parameters. We also employed photometric and proper motion data. The analysis method consists of the following steps： （i） analysis of the statistical resemblance between the cluster and a set of field samples with respect to the sequences defined in color-magnitude diagrams （CMDs）; （ii） a 5-dimensional iterative exclusion routine was employed to identify outliers from kinematical and posi- tional data; （iii） isochrone fitting to thes× （J - Ks） CMD of the remaining stars and the dispersion of spectral types along empirical sequences in the （J - H） × （H - Ks） diagram were checked. A group of stars was identified for which the mean heliocentric distance is compatible with that obtained via isochrone fitting and whose metallicities are compatible with each other. Fifteen of the member stars observed spectroscopically were identified together with another 19 probable members. Our results indi- cate that NGC 7193 is a genuine OCR, of a once very populous OC, for which the following parameters were derived： d = 501±46 pc, t = 2.5±1.2 Gyr, （[Fe/H]） = -0.17±0.23 and E（B-V） = 0.05±0.05. Its luminosity and mass functions show depletion of low mass stars, confirming the OCR is in a dynam- ically evolved state.展开更多
This work continues the previous study (2018) Journal of Modern Physics. 9, 1827-1837, that proposes that the disagreement arises because the cosmic microwave background (CMB) value for the Hubble constant <em>H...This work continues the previous study (2018) Journal of Modern Physics. 9, 1827-1837, that proposes that the disagreement arises because the cosmic microwave background (CMB) value for the Hubble constant <em>H</em><sub><em>0</em></sub> is actually for a universe which is decelerating rather than accelerating. It is shown that when <em>H</em><sub><em>0</em></sub> of Freedman et al. (2019) Astrophysical Journal, 882: 34 (24 pp.) is re-determined for redshift <em>z </em>= 0.07, by replacing <em>q</em><sub><em>0 </em></sub>= <span style="white-space:nowrap;">−</span>0.53 with <em style="white-space:normal;">q</em><sub style="white-space:normal;"><em>0 </em></sub><span style="white-space:normal;">= <span style="white-space:nowrap;">−</span>0.5</span>, the new lower value is in excellent agreement (0.1%) with the CMB <em>H</em><sub><em>0</em></sub>. The model is modified to include the clustering of galaxies, and the recognition that there are clusters that do not experience the Hubble expansion, such as the Local Group, and hence, in accordance with the model, within the Local Group the speed of light is <em>c</em>. The bearing of this result on the neutrino and light time delay from SN1987a is discussed. It is suggested that the possible emission of a neutrino from the blazar TXS-0506+56, that was flaring at the time, as well as possible neutrino emission earlier, may arise instead from a more distant source that happens to be, angle-wise, near the blazar, and hence the correlation is accidental. The model is further modified to allow for a variable index of refraction, and a comparison with the ΛCDM model is given. The age of the universe for different values of<em> H</em><sub><em>0</em></sub> is studied, and comparison with the ages of the oldest stars in the Milky Way is discussed. Also, gravitational wave determination of <em>H</em><sub><em>0</em></sub> is briefly discussed.展开更多
We examine 14 plates of the globular cluster M3 (NGC 5272) taken with the 40 cm refractor at the Sheshan station of Shanghai Astronomical Observatory. The plates span over a period of about 77 years. The positions and...We examine 14 plates of the globular cluster M3 (NGC 5272) taken with the 40 cm refractor at the Sheshan station of Shanghai Astronomical Observatory. The plates span over a period of about 77 years. The positions and absolute proper motions of eight stars in the Hipparcos Catalogue and of 49 stars in the Tycho-2 Catalogue are used as the reference frame. The astrometric reduction is made with the central overlapping principle. The absolute proper motions of 534 stars in a region of about 100' × 100' around the cluster are measured. With the new proper motion data the membership probabilities of the stars are determined. The average absolute proper motion obtained for the cluster is -0.06±0.30 mas yr-1 in R.A. and -2.6±0.30 mas yr-1 in Decl. By combining this result with the known distance and radial velocity of the cluster, we also obtained the Galactic orbit of M3 for a chosen three-component Galactic potential.展开更多
文摘The subject is the mass of the three dominant, equilibrium cosmological objects: the irregular galaxy (dwarf), the regular galaxy (Hubble’s “tuning fork”), and the galactic cluster. The standard ΛCDM theory and a DEH offer contrasting views on the origin of these masses. The latter suggests that they are relics of the early universe.
基金the Brazilian financial agencies FAPEMIG (grant APQ01858-12)CNPq+2 种基金the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technologyfunded by the National Aeronautics and Space Administrationthe National Science Foundation
文摘Galactic open clusters （OCs） that survive the early gas-expulsion phase are gradually de- stroyed over time by the action of disruptive dynamical processes. Their final evolutionary stages are characterized by a poorly populated concentration of stars called an open cluster remnant （OCR）. This study is devoted to assessing the real physical nature of the OCR candidate NGC 7193. GMOS/Gemini spectroscopy of 53 stars in the inner target region were obtained to derive radial velocities and at- mospheric parameters. We also employed photometric and proper motion data. The analysis method consists of the following steps： （i） analysis of the statistical resemblance between the cluster and a set of field samples with respect to the sequences defined in color-magnitude diagrams （CMDs）; （ii） a 5-dimensional iterative exclusion routine was employed to identify outliers from kinematical and posi- tional data; （iii） isochrone fitting to thes× （J - Ks） CMD of the remaining stars and the dispersion of spectral types along empirical sequences in the （J - H） × （H - Ks） diagram were checked. A group of stars was identified for which the mean heliocentric distance is compatible with that obtained via isochrone fitting and whose metallicities are compatible with each other. Fifteen of the member stars observed spectroscopically were identified together with another 19 probable members. Our results indi- cate that NGC 7193 is a genuine OCR, of a once very populous OC, for which the following parameters were derived： d = 501±46 pc, t = 2.5±1.2 Gyr, （[Fe/H]） = -0.17±0.23 and E（B-V） = 0.05±0.05. Its luminosity and mass functions show depletion of low mass stars, confirming the OCR is in a dynam- ically evolved state.
文摘This work continues the previous study (2018) Journal of Modern Physics. 9, 1827-1837, that proposes that the disagreement arises because the cosmic microwave background (CMB) value for the Hubble constant <em>H</em><sub><em>0</em></sub> is actually for a universe which is decelerating rather than accelerating. It is shown that when <em>H</em><sub><em>0</em></sub> of Freedman et al. (2019) Astrophysical Journal, 882: 34 (24 pp.) is re-determined for redshift <em>z </em>= 0.07, by replacing <em>q</em><sub><em>0 </em></sub>= <span style="white-space:nowrap;">−</span>0.53 with <em style="white-space:normal;">q</em><sub style="white-space:normal;"><em>0 </em></sub><span style="white-space:normal;">= <span style="white-space:nowrap;">−</span>0.5</span>, the new lower value is in excellent agreement (0.1%) with the CMB <em>H</em><sub><em>0</em></sub>. The model is modified to include the clustering of galaxies, and the recognition that there are clusters that do not experience the Hubble expansion, such as the Local Group, and hence, in accordance with the model, within the Local Group the speed of light is <em>c</em>. The bearing of this result on the neutrino and light time delay from SN1987a is discussed. It is suggested that the possible emission of a neutrino from the blazar TXS-0506+56, that was flaring at the time, as well as possible neutrino emission earlier, may arise instead from a more distant source that happens to be, angle-wise, near the blazar, and hence the correlation is accidental. The model is further modified to allow for a variable index of refraction, and a comparison with the ΛCDM model is given. The age of the universe for different values of<em> H</em><sub><em>0</em></sub> is studied, and comparison with the ages of the oldest stars in the Milky Way is discussed. Also, gravitational wave determination of <em>H</em><sub><em>0</em></sub> is briefly discussed.
基金NKBRSF19990754 and National Natural Sciences Foundation under grant 19833010．
文摘We examine 14 plates of the globular cluster M3 (NGC 5272) taken with the 40 cm refractor at the Sheshan station of Shanghai Astronomical Observatory. The plates span over a period of about 77 years. The positions and absolute proper motions of eight stars in the Hipparcos Catalogue and of 49 stars in the Tycho-2 Catalogue are used as the reference frame. The astrometric reduction is made with the central overlapping principle. The absolute proper motions of 534 stars in a region of about 100' × 100' around the cluster are measured. With the new proper motion data the membership probabilities of the stars are determined. The average absolute proper motion obtained for the cluster is -0.06±0.30 mas yr-1 in R.A. and -2.6±0.30 mas yr-1 in Decl. By combining this result with the known distance and radial velocity of the cluster, we also obtained the Galactic orbit of M3 for a chosen three-component Galactic potential.
