HCG 16 Revisited: Clues About Galaxy Evolution in Groups

We present new spectroscopic observations of 5 galaxies, members of the unusually active compact group HCG 16, observed using the Palomar 5m telescope. The high signal to noise ratios (S/N $\sim 70$) of the spectra allow us to study the variation of the emission line characteristics and the stellar populations in the nucleus and the circumnuclear regions of the galaxies. The emission line characteristics of these galaxies are complex, varying between Seyfert 2 and LINERs or between LINERs and starbursts. All of the galaxies show traces of intermediate age stellar populations, supporting our previous result that post-starburst galaxies are common in compact groups. The galaxies HCG16--4 and HCG16--5 show double nuclei and therefore could be two cases of recent merger. Our observations support a scenario where HCG 16 was formed by the successive merger of metal poor, low mass galaxies. The galaxies HCG16--1 and HCG16--2, which are more evolved, form the old core of the group. Galaxies HCG16--4 and HCG16--5 are two more recent additions still in a merging phase. Galaxy HCG16--5 is a starburst galaxy which is just beginning to fall into the core. If HCG 16 is representative of compact groups in their early stage, the whole set of observations implies that the formation of compact groups is the result of hierarchical galaxy formation. HCG 16 could be one example of this process operating in the local universe.Comment: tar file containing text and figures is available at http://www.daf.on.br/~reinaldo/paper.htm

The Relation Between Activity and Environment in Compact Groups of Galaxies

We present the results of the classification of spectral activity types for 193 galaxies from a new sample of 49 compact groups of galaxies in the southern hemisphere (SCGs). This sample was selected in automated fashion from a digitized galaxy catalogue, covering an area of ~5200 sq deg, around the South Galactic Pole. It is complete up to m ~14.5 in b_j for the brightest galaxy of the group. The spectral analysis of the SCG galaxies confirms the results previously obtained for a smaller sample of Hickson's compact groups (HCG). We confirm the luminosity-activity and morphology-activity relations, as well as the predominance of AGNs (41% of SCGs galaxies). We verified also that the number of early-type non-emission-line galaxies increases with the number of members in the group. The SCGs contain more star-forming galaxies (SFGs) and less non-emission-line galaxies than HCGs, which suggests that they probe a wider range of physical properties. The SFGs are composed in majority of HII Nucleus Galaxies, which have less intense star formation than starburst galaxies. The star formation activity in SCGs is, consequently, remarkably low. The SFGs show also evidence for nuclear activity. If these results are further confirmed, 70% of the galaxies in SCGs would then have an active nucleus, making these systems remarkably rich in AGNs. Curiously, however, this characteristic of CGs generally excludes Seyfert 1 galaxies.(Abridged)Comment: 53 pages, Latex, 9 encapsulated postscript figures, Accepted for publication in The Astronomical Journa

Academic Directors Facing Internet Addictions, Learning and Health Promotion

The result that is presented is expressed from a bibliographic review of works published during the last two years 2020-2022 and, through which it was possible to verify the relationships that are established between the work of the Academic Directors, before the latent challenge and visible that is the crossroads of Internet addictions, by university students, increased in the stage already overcome of social isolation imposed by Covid 19 but, with emphasis on the achievement of learning at this high educational level, its risks and consequent decreases in the attacks that occur as a result of procrastination. All associated with the addictive phenomenon, in a projection of health promotion that the current, humanistic, modern and developing university should not give up in any way, being precisely in this direction an unavoidable pillar of social development, which lies precisely in the high professional qualification. of the new generations committed to a prosperous and sustainable social change

Optical coherence tomography characteristics of group 2A idiopathic parafoveal telangiectasis

PURPOSE: To describe the optical coherence tomography (OCT) characteristics of patients with group 2A idiopathic parafoveal telangiectasis (IPFT) and to correlate them with biomicroscopic and fluorescein angiographic (FA) findings based on Gass and Blodi staging classification for group 2A IPFT. METHODS: Fifty-two eyes of 26 consecutive patients with IPFT underwent biomicroscopic fundus examination, color fundus photography, FA, and OCT. Main outcome measures were OCT characteristics and their correlation with biomicroscopy and FA. RESULTS: The most common OCT findings that help differentiate between stages in group 2A IPFT are 1) highly reflective dots in the inner retina that correspond with microvessels seen by FA in Stage 1 (5 eyes [62.5%]); 2) the presence of hyporeflective intraretinal spaces in the absence of retinal thickening and highly reflective dots in the retina in Stage 2 (9 [81.8%] and 10 eyes [90.9%], respectively); 3) in Stage 3, both outer and inner retina exhibit areas of similar high reflectivity. In addition, the retinal pigment epithelium (RPE)/choriocapillaris complex is thickened or disrupted as evidenced by an area of high reflectivity (13 eyes [81.2%]); 4) a highly reflective area nasal or temporal to the fovea in the inner or outer retinal layers in Stage 4 suggesting RPE proliferation and migration (13 eyes [100%]); and 5) a fusiform thickening and duplication of the highly reflective RPE/choriocapillaris complex corresponding to choroidal neovascularization in Stage 5 (4 eyes [100%]). Our OCT characteristics correlated well with biomicroscopic and FA findings for Stages 4 and 5. However, the hyporeflective spaces that are evident on OCT could not be seen clinically at the slit lamp or on FA. In addition, our OCT findings on eyes with group 2A IPFT Stage 3 have not, to our knowledge, been previously described. CONCLUSIONS: Optical coherence tomography findings in group 2A IPFT were characteristic for each stage and may be helpful in making the diagnosis as well as defining the anatomical staging proposed by Gass and Blodi. Optical coherence tomography complements biomicroscopic and FA findings in the evaluation of group 2A IPFT. © The Ophthalmic Communications Society, Inc

The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star-Black Hole Merger GW190814

We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and Thacher Telescope of the LIGO/Virgo gravitational wave (GW) signal from the neutron star-black hole (NSBH) merger GW190814. We searched the GW190814 localization region (19 deg$^{2}$ for the 90th percentile best localization), covering a total of 51 deg$^{2}$ and 94.6% of the two-dimensional localization region. Analyzing the properties of 189 transients that we consider as candidate counterparts to the NSBH merger, including their localizations, discovery times from merger, optical spectra, likely host-galaxy redshifts, and photometric evolution, we conclude that none of these objects are likely to be associated with GW190814. Based on this finding, we consider the likely optical properties of an electromagnetic counterpart to GW190814, including possible kilonovae and short gamma-ray burst afterglows. Using the joint limits from our follow-up imaging, we conclude that a counterpart with an $r$-band decline rate of 0.68 mag day$^{-1}$, similar to the kilonova AT 2017gfo, could peak at an absolute magnitude of at most $-17.8$ mag (50% confidence). Our data are not constraining for ''red'' kilonovae and rule out ''blue'' kilonovae with $M>0.5 M_{\odot}$ (30% confidence). We strongly rule out all known types of short gamma-ray burst afterglows with viewing angles $<$17$^{\circ}$ assuming an initial jet opening angle of $\sim$$5.2^{\circ}$ and explosion energies and circumburst densities similar to afterglows explored in the literature. Finally, we explore the possibility that GW190814 merged in the disk of an active galactic nucleus, of which we find four in the localization region, but we do not find any candidate counterparts among these sources.Comment: 86 pages, 9 figure