المؤلفون: Anupam Bhardwaj, Marcella Marconi, Marina Rejkuba, Richard de Grijs, Harinder P. Singh, Vittorio F. Braga, Shashi Kanbur, Chow-Choong Ngeow, Vincenzo Ripepi, Giuseppe Bono, Giulia De Somma, Massimo Dall’Ora

المصدر: The Astrophysical Journal Letters, Vol 944, Iss 2, p L51 (2023)

مصطلحات موضوعية: Globular star clusters, RR Lyrae variable stars, Distance indicators, Astrophysics, QB460-466

الوصف: RR Lyrae variables are excellent Population II distance indicators thanks to their well-defined period–luminosity relations (PLRs) at infrared wavelengths. We present results of near-infrared (NIR) monitoring of Galactic globular clusters to empirically quantify the metallicity dependence of NIR PLRs for RR Lyrae variables. Our sample includes homogeneous, accurate, and precise photometric data for 964 RR Lyrae variables in 11 globular clusters covering a large metallicity range (Δ[Fe/H] ∼ 2 dex). We derive JHK _s -band period–luminosity–metallicity (PLZ) and period–Wesenheit–metallicity (PWZ) relations anchored using 346 Milky Way field RR Lyrae stars with Gaia parallaxes, and simultaneously solved for independent distances to globular clusters. We find a significant metallicity dependence of ∼0.2 mag dex ^−1 in the JHK _s -band PLZ and PWZ relations for RR Lyrae stars independent of the adopted metallicity scale. The metallicity coefficients and the zero-points of the empirical PLZ and PWZ relations are in excellent agreement with the predictions from the horizontal branch evolution and pulsation models. Furthermore, RR Lyrae–based distances to our sample of globular clusters are also statistically consistent with other independent measurements in the literature. Our recommended empirical JHK _s -band PLZ relations for RR Lyrae stars with periods of fundamental mode pulsation ( P _f ) are: \begin{eqnarray*}\begin{array}{rcl}{M}_{J} & = & -0.44\,(\pm 0.03)-1.83\,(\pm 0.02)\mathrm{log}({P}_{{\rm{f}}})+0.20\,(\pm 0.02)\,[\mathrm{Fe}/{\rm{H}}]\,(\sigma =0.05\,\mathrm{mag})\\ {M}_{H} & = & -0.74\,(\pm 0.02)-2.29\,(\pm 0.02)\mathrm{log}({P}_{{\rm{f}}})+0.19\,(\pm 0.01)[\mathrm{Fe}/{\rm{H}}]\,(\sigma =0.05\,\mathrm{mag})\\ {M}_{{K}_{s}} & = & -0.80\,(\pm 0.02)-2.37\,(\pm 0.02)\mathrm{log}({P}_{{\rm{f}}})+0.18\,(\pm 0.01)\,[\mathrm{Fe}/{\rm{H}}]\,(\sigma =0.05\,\mathrm{mag}).\end{array}\end{eqnarray*}

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2041-8205Test

الوصول الحر: https://doaj.org/article/cbf576958b9f440ca45e3fe75f9babcbTest

المؤلفون: Misaki Mizumoto, Hiroaki Sameshima, Naoto Kobayashi, Noriyuki Matsunaga, Sohei Kondo, Satoshi Hamano, Chikako Yasui, Kei Fukue, Akira Arai, Hideyo Kawakita, Shogo Otsubo, Giuseppe Bono, Ivo Saviane

المصدر: The Astrophysical Journal, Vol 960, Iss 1, p 41 (2023)

مصطلحات موضوعية: Active galaxies, Astrophysics, QB460-466

الوصف: Outflows in an active galactic nucleus (AGN) are considered to play a key role in the evolution of the host galaxy through transfer of a large amount of energy. A narrow-line region (NLR) in the AGN is composed of ionized gas extending from parsec to kiloparsec scales. It has been suggested that shocks are required to ionize the NLR gas. If AGN outflows generate these shocks, they will sweep through the NLR, and the outflow energy will be transferred into a galaxy-scale region. In order to study the contribution of the AGN outflow to the NLR-scale shock, we measure the [Fe ii ] λ 12570/[P ii ] λ 11886 line ratio, which is a good tracer of shocks, using near-infrared spectroscopic observations with the Warm INfrared Echelle spectrograph to Realize Extreme Dispersion and sensitivity (WINERED) mounted on the New Technology Telescope. In 13 Seyfert galaxies we observed, the [Fe ii ] and [P ii ] lines were detected in 12 and 6 targets, respectively. The [Fe ii ]/[P ii ] ratios in 4 targets were found to be higher than 10, which implies the existence of shocks. We also found that the shock is likely to exist where an ionized outflow, i.e., a blue wing in [S iii ] λ 9533, is present. Our result implies that the ionized outflow present in an NLR-scale region sweeps through the interstellar medium and generates a shock.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-4357Test

الوصول الحر: https://doaj.org/article/fb871a13c547479ea267a19f9d3bfcf1Test

المؤلفون: Noriyuki Matsunaga, Daisuke Taniguchi, Scarlet S. Elgueta, Takuji Tsujimoto, Junichi Baba, Andrew McWilliam, Shogo Otsubo, Yuki Sarugaku, Tomomi Takeuchi, Haruki Katoh, Satoshi Hamano, Yuji Ikeda, Hideyo Kawakita, Charlie Hull, Rogelio Albarracín, Giuseppe Bono, Valentina D’Orazi

المصدر: The Astrophysical Journal, Vol 954, Iss 2, p 198 (2023)

مصطلحات موضوعية: Cepheid variable stars, Metallicity, Milky Way disk, Young disk Cepheid variable stars, Infrared spectroscopy, Astrophysics, QB460-466

الوصف: Metallicity gradients refer to the sloped radial profiles of the metallicities of gas and stars and are commonly seen in disk galaxies. A well-defined metallicity gradient of the Galactic disk is observed particularly well with classical Cepheids, which are good stellar tracers thanks to their period–luminosity relation, allowing precise distance estimation and other advantages. However, the measurement of the inner-disk gradient has been impeded by the incompleteness of previous samples of Cepheids and the limitations of optical spectroscopy in observing highly reddened objects. Here we report the metallicities of 16 Cepheids measured with high-resolution spectra in the near-infrared YJ bands. These Cepheids are located at 3–5.6 kpc in Galactocentric distance, R _GC , and reveal the metallicity gradient in this range for the first time. Their metallicities are mostly between 0.1 and 0.3 dex in [Fe/H] and more or less follow the extrapolation of the metallicity gradient found in the outer part, R _GC > 6.5 kpc. The gradient in the inner disk may be shallower or even flat, but the small sample does not allow the determination of the slope precisely. More extensive spectroscopic observations would also be necessary for studying minor populations, if any, with higher or lower metallicities that were reported in previous literature. In addition, the 3D velocities of our inner-disk Cepheids show a kinematic pattern that indicates noncircular orbits caused by the Galactic bar, which is consistent with the patterns reported in recent studies on high-mass star-forming regions and red giant branch stars.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-4357Test

الوصول الحر: https://doaj.org/article/920880fa2faf46028611c25cf0c6fb10Test

المؤلفون: Piero Trevisan, Mario Pasquato, Gaia Carenini, Nicolas Mekhaël, Vittorio F. Braga, Giuseppe Bono, Mohamad Abbas

المصدر: The Astrophysical Journal, Vol 950, Iss 2, p 103 (2023)

مصطلحات موضوعية: Astrostatistics, Stellar classification, Eclipsing binary stars, Intrinsic variable stars, Periodic variable stars, RRc variable stars, Astrophysics, QB460-466

الوصف: RR Lyrae (RRL) stars are old, low-mass, radially pulsating variable stars in their core helium burning phase. They are popular stellar tracers and primary distance indicators since they obey well-defined period–luminosity relations in the near-infrared regime. Their photometric identification is not trivial; indeed, RRL star samples can be contaminated by eclipsing binaries, especially in large data sets produced by fully automatic pipelines. Interpretable machine-learning approaches for separating eclipsing binaries from RRL stars are thus needed. Ideally, they should be able to achieve high precision in identifying RRL stars while generalizing new data from different instruments. In this paper, we train a simple logistic regression classifier on Catalina Sky Survey (CSS) light curves. It achieves a precision of 87% at 78% recall for the RRL star class on unseen CSS light curves. It generalizes on out-of-sample data (ASAS/ASAS-SN light curves) with a precision of 85% at 96% recall. We also considered a L1-regularized version of our classifier, which reaches 90% sparsity in the light-curve features with a limited trade-off in accuracy on our CSS validation set and—remarkably—also on the ASAS/ASAS-SN light-curve test set. Logistic regression is natively interpretable, and regularization allows us to point out the parts of the light curves that matter the most in classification. We thus achieved both good generalization and full interpretability.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-4357Test

الوصول الحر: https://doaj.org/article/f6c9cf695a4340a69473e70488cefe59Test

المؤلفون: Christian I. Johnson, Annalisa Calamida, Justin A. Kader, Ivan Ferraro, Catherine A. Pilachowski, Giuseppe Bono, Alessandra Mastrobuono-Battisti, Armin Rest, Alfredo Zenteno, Alice Zocchi

المصدر: The Astronomical Journal, Vol 166, Iss 1, p 3 (2023)

مصطلحات موضوعية: Globular star clusters, Astronomy, QB1-991

الوصف: Wide-field and deep DECam multiband photometry, combined with HST data for the core of the Galactic globular cluster NGC 2808, allowed us to study the distribution of various stellar subpopulations and stars in different evolutionary phases out to the cluster tidal radius. We used the C _ugi = ( u − g ) − ( g − i ) index to identify three chemically distinct subpopulations along the red giant branch and compared their spatial distributions. The most light-element-enriched subpopulation (P3) is more centrally concentrated; however, it shows a more extended distribution in the external regions of the cluster compared to the primordial (P1) and intermediate (P2) composition populations. Furthermore, the P3 subpopulation centroid is off-center relative to those of the P1 and P2 groups. We also analyzed the spatial distribution of horizontal branch stars and found that the relative fraction of red horizontal branch stars increases for radial distances larger than ≈1.′5, while that of the blue and hotter stars decreases. These new observations, combined with literature spectroscopic measurements, suggest that the red horizontal branch stars are the progeny of all the stellar subpopulations in NGC 2808, i.e., primordial and light-element enhanced, while the blue stars are possibly the result of a combination of the “hot-flasher” and the “helium-enhanced” scenarios. A similar distribution of different red giant branch subpopulations and horizontal branch stars was also found for the most massive Galactic globular cluster, ω Cen, based on combined DECam and HST data, which suggests that the two may share a similar origin.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-3881Test

الوصول الحر: https://doaj.org/article/00ed64ce05804d5ebc7b74c7b56a236cTest

المؤلفون: Joseph P. Mullen, Massimo Marengo, Clara E. Martínez-Vázquez, Brian Chaboyer, Giuseppe Bono, Vittorio F. Braga, Massimo Dall’Ora, Valentina D’Orazi, Michele Fabrizio, Matteo Monelli, Frédéric Thévenin

المصدر: The Astrophysical Journal, Vol 945, Iss 1, p 83 (2023)

مصطلحات موضوعية: RR Lyrae variable stars, Standard candles, Stellar distance, Astrophysics, QB460-466

الوصف: We present new empirical infrared period–luminosity–metallicity (PLZ) and period–Wesenheit–metallicity (PWZ) relations for RR Lyae based on the latest Gaia Early Data Release 3 (EDR3) parallaxes. The relations are provided in the Wide-field Infrared Survey Explorer (WISE) W1 and W2 bands, as well as in the W(W1, V − W1) and W(W2, V − W2) Wesenheit magnitudes. The relations are calibrated using a very large sample of Galactic halo field RR Lyrae stars with homogeneous spectroscopic [Fe/H] abundances (over 1000 stars in the W1 band), covering a broad range of metallicities (−2.5 ≲ [Fe/H] ≲ 0.0). We test the performance of our PLZ and PWZ relations by determining the distance moduli of both galactic and extragalactic stellar associations: the Sculptor dwarf spheroidal galaxy in the Local Group (finding ${\bar{\mu }}_{0}=19.47\pm 0.06$ ), the Galactic globular clusters M4 ( ${\bar{\mu }}_{0}=11.16\pm 0.05$ ), and the Reticulum globular cluster in the Large Magellanic Cloud ( ${\bar{\mu }}_{0}=18.23\pm 0.06$ ). The distance moduli determined through all our relations are internally self-consistent (within ≲0.05 mag) but are systematically smaller (by ∼2–3 σ ) than previous literature measurements taken from a variety of methods/anchors. However, a comparison with similar recent RR Lyrae empirical relations anchored with EDR3 likewise shows, to varying extents, a systematically smaller distance modulus for PLZ/PWZ RR Lyrae relations.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1538-4357Test

الوصول الحر: https://doaj.org/article/a3c70a7157a444af82f816028ab05970Test

المؤلفون: Giuseppe Bono, Pilar Maria Guerrieri

المصدر: Techne, Iss 2 (2021)

مصطلحات موضوعية: Algorithmic Design, Architecture, Authorship, Creativity, Digital Architecture, Aesthetics of cities. City planning and beautifying, NA9000-9428, Architectural drawing and design, NA2695-2793

الوصف: The paper seeks to define the concept of digital anonymity. Digital anonymity is defined as the autopoietic condition of architectural design in the digital era, a state in which the combination of decontextualisation and depersonalisation of the design process leads towards emergent and anonymous design results. Starting from the analysis of principles coming from the architectural world and then extending their definitions to considerations relative to other disciplines, the paper tries to delineate a new ethic of human-machine interaction and integration in the current architectural discipline. The evidence suggests that digital anonymity is the touchstone of an ongoing evolutionary process, which is translating architectural design into its new digital realm.

وصف الملف: electronic resource

العلاقة: https://oaj.fupress.net/index.php/techne/article/view/10705Test; https://doaj.org/toc/2239-0243Test

الوصول الحر: https://doaj.org/article/b8812cccd30148b59afcc139aec9956cTest

المؤلفون: Juliana Crestani, Alan Alves-Brito, Giuseppe Bono, Arthur A Puls, Javier Alonso-García

المصدر: Monthly Notices of the Royal Astronomical Society. 487(4):5463-5474

الوصول الحر: https://ntrs.nasa.gov/citations/17444124250561Test

المؤلفون: Giuseppe, Bono, Filippina, Caputo, Marcella, Marconi

مصطلحات موضوعية: Astrophysics

الوصف: We present the results of a comprehensive theoretical investigation on the Period-Radius (PR) relation of classical Cepheids based on new sequences of full amplitude, nonlinear convective models constructed by adopting a wide range of both stellar masses and chemical compositions. For log P in the range 0.9 - 1.8 a very good agreement is found between theoretical predictions and current available data whereas outside this range, both at shorter and at longer periods, nonlinear radii attain intermediate values between empirical relations based on different Baade-Wesselink (BW) methods and photometric bandpasses.
Comment: 11 pages of tex file, 4 Postrscript figures; style used aaspp4.sty

الوصول الحر: http://arxiv.org/abs/astro-ph/9802127Test

المؤلفون: Giuseppe, Bono, Marcella, Marconi

مصطلحات موضوعية: Astrophysics

الوصف: We present nonlinear theoretical results concerning the predicted pulsation behaviour of stellar models suitable for the sample of Cepheids belonging to the Large Magellanic Cloud (LMC) star cluster NGC 1866. The blue and red edges of the instability strip, transformed into the observative plane (V, B-V) by adopting current values for the distance modulus (DM=18.57 mag., Welch et al. 1991) and for the reddening (E(B-V)=0.06 mag., Arp 1967; Walker 1974; Walker 1987), are in agreement with the observed distribution of Cepheids in the quoted cluster. Moreover, the distribution of observational data in the Bailey diagram (V amplitude versus period) appears in agreement with theoretical predictions derived adopting the luminosity level predicted by canonical evolutionary models. The role played by the direct integration of the coupling between pulsation and convection and by the input physics on the smoothness of light and velocity curves is briefly discussed.
Comment: 5 pages of tex file, 1 latex table, 4 Postrscript figures; style used mnrass.sty

الوصول الحر: http://arxiv.org/abs/astro-ph/9705150Test