Imagery and long-slit spectroscopy of the Polar-Ring Galaxy AM2020-504

Interactions between galaxies are very common. There are special kinds of interactions that produce systems called Polar Ring Galaxies (PRGs), composed by a lenticular, elliptical, or spiral host galaxy, surrounded by a ring of stars and gas, orbiting in an approximately polar plane. The present work aims to study AM2020-504, a PRG with an elliptical host galaxy, and a narrow and well defined ring, probably formed by accretion of material from a donor galaxy, collected by the host galaxy. Our observational study was based on BVRI broad band imagery as well as longslit spectroscopy in the wavelenght range 4100--8600\AA, performed at the 1.6m telescope at the Observat\'orio do Pico dos Dias (OPD), Brazil. We estimated a redshift of z= 0.01683, corresponding a heliocentric radial velocity of 5045 +/-23 km/s. The (B-R) color map shows that the ring is bluer than the host galaxy, indicating that the ring is a younger structure. Standard diagnostic diagrams were used to classify the main ionizing source of selected emission-line regions (nucleus, host galaxy and ring). It turns out that the ring regions are mainly ionized by massive stars while the nucleus presents AGN characteristics. Using two empirical methods, we found oxygen abundances for the HII regions located in the ring in the range 12+log(O/H)=8.3-8.8 dex, the presence of an oxygen gradient across the ring, and that AM2020-504 follows the metallicity-luminosity relation of spiral galaxies. These results support the accretion scenario for this object and rules out cold accretion as source for the HI gas in the polar ring

Magnetic Field Reconstruction for a Realistic Multi-Point, Multi-Scale Spacecraft Observatory

Future in situ space plasma investigations will likely involve spatially distributed observatories comprised of multiple spacecraft, beyond the four and five spacecraft configurations currently in operation. Inferring the magnetic field structure across the observatory, and not simply at the observation points, is a necessary step towards characterizing fundamental plasma processes using these unique multi-point, multi-scale data sets. We propose improvements upon the classic first-order reconstruction method, as well as a second-order method, utilizing magnetometer measurements from a realistic nine-spacecraft observatory. The improved first-order method, which averages over select ensembles of four spacecraft, reconstructs the magnetic field associated with simple current sheets and numerical simulations of turbulence accurately over larger volumes compared to second-order methods or first-order methods using a single regular tetrahedron. Using this averaging method on data sets with fewer than nine measurement points, the volume of accurate reconstruction compared to a known magnetic vector field improves approximately linearly with the number of measurement points

Interaction effects on galaxy pairs with Gemini/GMOS- II: Oxygen abundance gradients

In this paper we derived oxygen abundance gradients from HII regions located in eleven galaxies in eight systems of close pairs. Long-slit spectra in the range 4400-7300A were obtained with the Gemini Multi-Object Spec- trograph at Gemini South (GMOS). Spatial profiles of oxygen abundance in the gaseous phase along galaxy disks were obtained using calibrations based on strong emission-lines (N2 and O3N2). We found oxygen gradients signifi- cantly flatter for all the studied galaxies than those in typical isolated spiral galaxies. Four objects in our sample, AM1219A, AM1256B, AM 2030A and AM2030B, show a clear break in the oxygen abundance at galactocentric radius R/R25 between 0.2 and 0.5. For AM1219A and AM1256B we found negative slopes for the inner gradients, and for AM2030B we found a positive one. In all these three cases they show a flatter behaviour to the outskirts of the galaxies. For AM2030A, we found a positive-slope outer gradient while the inner one is almost compatible with a flat behaviour. A decrease of star forma- tion efficiency in the zone that corresponds to the oxygen abundance gradient break for AM1219A and AM2030B was found. For the former, a minimum in the estimated metallicities was found very close to the break zone that could be associated with a corotation radius. On the other hand, AM1256B and AM2030A, present a SFR maximum but not an extreme oxygen abundance value. All the four interacting systems that show oxygen gradient breakes the extreme SFR values are located very close to break zones. Hii regions lo- cated in close pairs of galaxies follow the same relation between the ionization parameter and the oxygen abundance as those regions in isolated galaxies.Comment: 30 pages, 14 figures, accepted MNRAS, (Figs. 1 and 2 are in low resolution

Effective temperature of ionizing stars in extragalactic HII regions - II. Nebular parameter relationships based on CALIFA data

We calculate the effective temperature (Teff) of ionizing star(s), the oxygen abundance of the gas phase (O/H), and the ionization parameter U for a sample of HII regions located in the discs of 59 spiral galaxies in the redshift range 0.005 < z < 0.03. We use spectroscopic data taken from the CALIFA data release 3 (DR3) and theoretical (for Teff and U) and empirical (for O/H) calibrations based on strong emission lines. We consider the spatial distribution and radial gradients of these parameters in each galactic disc for the objects in our sample. Most of the galaxies in our sample (∼70 per cent) show positive Teff radial gradients, although some exhibit negative or flat ones. The median value of the Teff radial gradient is 0.762 kK/R25. We find that the radial gradients of both logUand Teff depend on the oxygen abundance gradient, in the sense that the gradient of logU increases as the log(O/H) gradient increases while there is an anti-correlation between the gradient of Teff and the oxygen abundance gradient. Moreover, galaxies with flat oxygen abundance gradients tend to have flat logU and Teff gradients as well. Although our results are in agreement with the idea of the existence of positive Teff gradients along the disc of the majority of spiral galaxies, it seems that this is not a universal property for these objects.Fil: Zinchenko, I. A.. Main Astronomical Observatory of National Academy of Sciences of Ukraine; Ucrania. Zentrum für Astronomie der Universität Heidelberg; AlemaniaFil: Dors, Oli L.. Universidade do Vale do Paraíba; BrasilFil: Hägele, Guillermo Federico. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cardaci, Monica Viviana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Krabbe, Angela. Universidade do Vale do Paraíba; Brasi

Detection of Porcine Circovirus 3 in Wildlife Species in Spain

Porcine circovirus 3 (PCV-3) is the third member of the family Circoviridae, genus Circovirus, able to infect swine. A high prevalence of viral DNA has been recorded in wild boars. Recently, PCV-3 DNA was identified in Italian wild ruminants. Based on these previous results, this study assessed the frequency of PCV-3 DNA detection in free-ranging ruminants and Lagomorpha species in Spain. In addition, the genetic characterization of the PCV-3 PCR-positive samples was performed. A total of 801 serum samples, including red deer (Cervus elaphus, [CE]; n = 108), roe deer (Capreolus capreolus, [CC]; n = 87), Pyrenean chamois (Rupicapra pyrenaica, [RP]; n = 133), Iberian ibex (Capra pyrenaica, [CP]; n = 92), mouflon (Ovis aries, [OA]; n = 91), fallow deer (Dama dama, [DD]; n = 104), European rabbit (Oryctolagus cuniculus, [OC]; n = 101), and European hare (Lepus europaeus, [LE]; n = 85) from Catalonia (northeast Spain) were tested by conventional polymerase chain reaction (PCR) and, when positive, sequenced. Overall, PCV-3 DNA was found in three out of 801 analyzed sera (0.37%) corresponding to one red deer (1/108, 0.9%), one mouflon (1/91, 1.1%), and one fallow deer (1/104, 0.96%). None of the samples collected from Lagomorpha species resulted PCR positive. The partial genome sequences detected in positive samples displayed high identity with some PCV-3 sequences detected in wild boars and domestic pigs (99.7% and 100%, respectively). In conclusion, the present study indicated that free-ranging ruminant and Lagomorpha species are not relevant in the epidemiology of PCV-3 in Spain.info:eu-repo/semantics/publishedVersio

Calibration-based abundances in the interstellar gas of galaxies from slit and IFU spectra

In this work we make use of available Integral Field Unit (IFU) spectroscopy and slit spectra of several nearby galaxies. The pre-existing empirical R and S calibrations for abundance determinations are constructed using a sample of HII regions with high quality slit spectra. In this paper, we test the applicability of those calibrations to the IFU spectra. We estimate the calibration-based abundances obtained using both the IFU and the slit spectroscopy for eight nearby galaxies. The median values of the slit and IFU spectra-based abundances in bins of 0.1 in fractional radius Rg (normalized to the optical radius) of a galaxy are determined and compared. We find that the IFU and the slit spectra-based abundances obtained through the R calibration are close to each other, the mean value of the differences of abundances is 0.005 dex and the scatter in the differences is 0.037 dex for 38 datapoints. The S calibration can produce systematically underestimated values of the IFU spectra-based abundances at high metallicities, the mean value of the differences is -0.059 dex for 21 datapoints, while at lower metallicities the mean value of the differences is -0.018 dex and the scatter is 0.045 dex for 36 data points. This evidences that the R calibration produces more consistent abundance estimations between the slit and the IFU spectra than the S calibration. We find that the same calibration can produce close estimations of the abundances using IFU spectra obtained with different spatial resolution and different spatial samplings. This is in line with the recent finding that the contribution of the diffuse ionized gas to the large aperture spectra of HII regions has a secondary effect.Comment: 15 pages, 14 figures, accepted to the Astronomy and Astrophysic

Chemical abundance of the LINER galaxy UGC 4805 with SDSS-IV MaNGA

Chemical abundance determinations in Low-Ionization Nuclear Line Regions (LINERs) are especially complex and uncertain because the nature of the ionizing source of this kind of object is unknown. In this work, we study the oxygen abundance in relation to the hydrogen abundance (O/H) of the gas phase of the UGC 4805 LINER nucleus. Optical spectroscopic data from the Mapping Nearby Galaxies (MaNGA) survey was employed to derive the O/H abundance of the UGC 4805 nucleus based on the extrapolation of the disk abundance gradient, on calibrations between O/H abundance and strong emission-lines for Active Galactic Nuclei (AGNs) as well as on photoionization models built with the Cloudy code, assuming gas accretion into a black hole (AGN) and post-Asymptotic Giant Branch (p-AGB) stars with different effective temperatures. We found that abundance gradient extrapolations, AGN calibrations, AGN and p-AGB photoionization models produce similar O/H values for the UGC 4805 nucleus and similar ionization parameter values. The study demonstrated that the methods used to estimate the O/H abundance using nuclear emission-line ratios produce reliable results, which are in agreement with the O/H values obtained from the independent method of galactic metallicity gradient extrapolation. Finally, the results from the WHAN diagram combined with the fact that the high excitation level of the gas has to be maintained at kpc scales, we suggest that the main ionizing source of the UGC 4805 nucleus probably has a stellar origin rather than an AGN.Fil: Krabbe, Angela. Universidade Do Vale Do Paraíba; BrasilFil: Oliveira, C. B.. Universidade Do Vale Do Paraíba; BrasilFil: Zinchenko, I. A.. Universitat Ulm. Faculty Of Natural Sciences. Institute Of Theoretical Physics; AlemaniaFil: Hernández Jiménez, J. A.. Universidad Andrés Bello; ChileFil: Dors, Oli L.. Universidade Do Vale Do Paraíba; BrasilFil: Hägele, Guillermo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cardaci, Monica Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Telles, N. R.. Universidade Do Vale Do Paraíba; Brasi

The effects of the interaction on the kinematics, stellar population and metallicity of AM2322-821 with Gemini/GMOS

We present an observational study about the impacts of the interactions in the kinematics, stellar populations, and oxygen abundances of the components of the galaxy pair AM\,2322-821. A fairly symmetric rotation curve for the companion (AM\,2322B) galaxy with a deprojected velocity amplitude of 110 km s$^{-1}$ was obtained, and a dynamical mass of 1.1 - 1.3 \times 10^{10} M_{\sun} within a radius of 4 kpc was estimated using this deprojected velocity. Asymmetries in the radial velocity field were detected for the companion, very likely due the interaction between the galaxies. The interaction between the main and companion galaxies was modelled using numerical N-body/hydrodynamical simulations, with the result indicating that the current stage of the system would be about 90 Myr after perigalacticum. The spatial variation in the distribution of the stellar-population components in both galaxies was analysed using the stellar population synthesis code {\sc STARLIGHT}. The companion galaxy is dominated by a very young (t $\leq 1\times10^{8}$ yr) population, with the fraction of this population to the total flux at $\lambda\, 5\,870\, \AA$, increasing outwards in the galaxy disc. On the other hand, the stellar population of AM\,2322A is heterogeneous along the slit positions observed. Spatial profiles of oxygen abundance in the gaseous phase were obtained using the diagnostic diagram R23 vs. [OIII]/[OII], where we compared the observed values with the ones obtained from photoionization models. Such gradients of oxygen abundance are significantly flatter for this pair of galaxies than in typical isolated spiral galaxies. This metallicity distribution is interpreted as the gradients having been destroyed by interaction-induced gas flows from the outer parts to the centre of the galaxyComment: accepted by MNRA

On the central abundances of Active Galactic Nuclei and Star-forming Galaxies

We examine the relation between oxygen abundances in the narrow-line regions (NLRs) of active galactic nuclei (AGNs) estimated from the optical emission lines through the strong-line method (the theoretical calibration of Storchi-Bergmann et al. 1998), via the direct Te-method, and the central intersect abundances in the host galaxies determined from the radial abundance gradients. We found that the Te-method underestimates the oxygen abundances by up to ∼2 dex (with average value of ~0.8 dex) compared to the abundances derived through the strong-line method. This con- firms the existence of the so-called ?temperature problem? in AGNs. We also found that the abundances in the centres of galaxies obtained from their spectra trough the strong-line method are close to or slightly lower than the central intersect abun- dances estimated from the radial abundance gradient both in AGNs and Star-forming galaxies. The oxygen abundance of the NLR is usually lower than the maximum at- tainable abundance in galaxies (~2 times the solar value). This suggests that there is no extraordinary chemical enrichment of the NLRs of AGNs.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat