Dennis Edward Hyde, Letícia Pereira Alves, Daniel Rodrigues Costa Mello
et al.
This article presents the National Parks Astrotourism Potential Index (IASTRO), an innovative tool to evaluate and compare the potential for astro tourism in the 75 Brazilian national parks. IASTRO combines three crucial parameters: night sky quality, open sky probability, and tourism infrastructure, which encompasses the presence of guides and the availability of different experiences of overnight stays. The detailed methodology for data collection and IASTRO calculation is described, including the weighting of parameters, with night sky quality receiving greater weight for its fundamental importance for celestial observation. The results reveal a diverse distribution of IASTRO among the parks, highlighting those located in the Cerrado and Caatinga biomes, which present more favorable night sky and climatological conditions. The in-depth discussion explores the relationship between IASTRO and other factors, such as the number of visitors and the characteristics of the biomes, revealing an untapped potential for astro tourism in many national parks. The study also highlights the importance of tourism infrastructure and simulates how improvements in this aspect can boost astro tourism potential in various parks. The final considerations emphasize IASTRO as a valuable tool for protected area management and for the formulation of public policies, promoting the preservation of the starry sky and the development of astro tourism in a sustainable way. The article concludes that Brazil has enormous potential to become a world-class astro tourism destination, with its national parks offering exceptional conditions for celestial observation and connection with nature. This pioneering study contributes to the field of ecotourism by providing a comprehensive and innovative index to assess the astro tourism potential in national parks. IASTRO can be used by park managers, researchers, tourists, astronomy enthusiasts and policy makers to identify and prioritize parks with greater potential for this activity, assisting in the planning of actions and investments that promote the development of astro tourism in Brazil. In summary, the article presents an innovative index to assess the astro tourism potential in Brazilian national parks, highlighting the importance of night sky quality, open sky probability, and tourism infrastructure. The study reveals an untapped potential for astro tourism in many parks and highlights the importance of investments in tourism infrastructure to boost this activity. IASTRO is presented as a valuable tool for protected area management and for the formulation of public policies, aiming at the sustainable development of astro tourism in Brazil.
Yuan-Sen Ting, Alberto Accomazzi, Tirthankar Ghosal
et al.
We present a dataset of 408,590 astrophysics papers from arXiv (astro-ph), spanning 1992 through July 2025. Each paper has been processed through a multi-stage pipeline to produce: (1) structured summaries organized into six semantic sections (Background, Motivation, Methodology, Results, Interpretation, Implication), and (2) concept extraction yielding 9,999 unique concepts with detailed descriptions. The dataset contains 3.8 million paper-concept associations and includes semantic embeddings for all concepts. Comparison with traditional ADS keywords reveals that the concepts provide denser coverage and more uniform distribution, while analysis of embedding space structure demonstrates that concepts are semantically dispersed within papers-enabling discovery through multiple diverse entry points. Concept vocabulary and embeddings are publicly released at https://github.com/tingyuansen/astro-ph_knowledge_graph.
I. H. Hashim, H. Ejiri, N. N. A. M. A. Ghani
et al.
\item[Background] The nuclear responses for antineutrinos associated with double beta decays (DBDs) and astro-antineutrino interactions are studied by measuring ordinary muon capture (OMC) rates. \item[Purpose]The experimental studies of absolute OMC rates and their mass number dependence for $^{100}$Mo and the natural Mo are currently of interest in astro-antineutrinos and DBDs. \item[Method]The OMC rates were obtained experimentally by measuring the time spectrum of the trapped muon's decay into electrons to obtain the half-lives of the trapped muons. \item[Results]The OMC rate for the enriched isotope of $^{100}$Mo is $Λ$($^{100}$Mo)=(7.07$\pm$0.32)$\times10^{6}$ s$^{-1}$, while that for the natural Mo is $Λ$($^{\rm nat}$Mo)=(9.66$\pm$0.44)$\times10^{6}$ s$^{-1}$, i.e., $Λ$($^{100}$Mo) is about 27$\%$ of $Λ$($^{\rm nat}$Mo), reflecting the blocking effect of the excess neutrons for the proton-to-neutron transformation in OMC. The present experimental observation is consistent with the predictions using Goulard-Primakoff's (GPs) and Primakoff's (Ps) empirical equations. \item[Conclusions] The absolute OMC rates for $^{100}$Mo and $^{\rm nat}$Mo were measured. The large neutron excess in $^{100}$Mo gives a much lower OMC rate than $^{\rm nat}$Mo. On both $^{100}$Mo and $^{\rm nat}$Mo, consistent OMC rates with the GP and P values are observed.
O objetivo deste artigo é mostrar o motivo de se considerar a matéria escura como ingrediente fundamental para o Universo. A existência da matéria escura é indispensável para formar as estruturas cósmicas que observamos como galáxias e aglomerados de galáxias. Apesar de ainda desconhecermos a natureza desta componente cósmica, pois ainda não a detectamos diretamente, o aspecto discutido neste trabalho é considerado um dos principais argumentos a favor da existência da matéria escura.
Desde tempos imemoriais que os seres humanos olham e tentam perceber o céu. Não sabiam bem o que eram aquelas luzes a brilhar e que se movimentavam de forma repetida. Hoje em dia parece muito fácil, mas demorou muito tempo a consolidar-se a imagem que atualmente temos do céu. E sobretudo, a sabermos qual era a sua composição química. Este artigo pretende fazer uma revisão de divulgação do conhecimento químico que temos do céu e mostrar que as informações químicas são indissociáveis do entendimento que temos hoje do universo.
Neste artigo explicamos o que são as ondas gravitacionais previstas pela teoria da relatividade geral de Einstein, falamos de suas fontes astrofísicas e cosmológicas e dos detectores que foram utilizados para a sua busca. Completamos o artigo com a menção aos detectores futuros, que estão sendo projetados para dar uma nova dimensão à astronomia de ondas gravitacionais e à astronomia multimensageira envolvendo ondas gravitacionais.
Discuto alguns aspectos do chamado “paradigma da luz cansada”, o qual representa uma das possíveis explicações para a dependência do desvio espectral para o vermelho de uma fonte cósmica distante com a sua distância até o observador. A mais popular representação fenomenológica do paradigma é apresentada em algum detalhe. Além disso, sendo o processo físico responsável pelo hipotético fenômeno ainda desconhecido, apresento também uma sugestão para a sua descoberta.
Paul B. Rimmer, Sean Jordan, Tereza Constantinou
et al.
The depletion of SO$_2$ and H$_2$O in and above the clouds of Venus (45 -- 65 km) cannot be explained by known gas-phase chemistry and the observed composition of the atmosphere. We apply a full-atmosphere model of Venus to investigate three potential explanations for the SO$_2$ and H$_2$O depletion: (1) varying the below-cloud water vapor (H$_2$O), (2) varying the below-cloud sulfur dioxide (SO$_2$), and (3) the incorporation of chemical reactions inside the sulfuric acid cloud droplets. We find that increasing the below-cloud H$_2$O to explain the SO$_2$ depletion results in a cloud top that is 20 km too high, above-cloud O$_2$ three orders of magnitude greater than observational upper limits and no SO above 80 km. The SO$_2$ depletion can be explained by decreasing the below-cloud SO$_2$ to $20\,{\rm ppm}$. The depletion of SO$_2$ in the clouds can also be explained by the SO$_2$ dissolving into the clouds, if the droplets contain hydroxide salts. These salts buffer the cloud pH. The amount of salts sufficient to explain the SO$_2$ depletion entail a droplet pH of $\sim 1$ at 50 km. Since sulfuric acid is constantly condensing out into the cloud droplets, there must be a continuous and pervasive flux of salts of $\approx 10^{-13} \, {\rm mol \, cm^{-2} \, s^{-1}}$ driving the cloud droplet chemistry. An atmospheric probe can test both of these explanations by measuring the pH of the cloud droplets and the concentrations of gas-phase SO$_2$ below the clouds.
Razmik Mirzoyan, Cornelia Arcaro, Hanna Kellermann
et al.
The absolute reflectance of a reflector and its point spread function are the key parameters of a telescope for measuring light flux. Typically, one is using low-cost technologies for producing mirrors for the needs of astro-particle physics experiments. As a rule, these are operating telescopes in open air conditions at desert or mountainous locations, for cost reasons without protecting domes. The mirrors on such telescopes are exposed to sand in strong winds, precipitation and large temperature variations. Due to weathering, their reflectance is declining within few years. In this report we describe in a great detail the application of an in-situ method to the MAGIC imaging air Cherenkov telescopes for regularly monitoring their absolute reflectance and the point spread function. Compared to similar work that was previously performed, in this report we focus on important details of light losses due to scattering. These allowed us to further refine the method and significantly improve its precision. Also, we report on an in-situ comparison of two mirror types produced with different technologies.
We study ocean exoplanets, for which the global surface ocean is separated from the rocky interior by a high-pressure ice mantle. We describe a mechanism that can pump salts out of the ocean, resulting in oceans of very low salinity. Here we focus on the H2O-NaCl system, though we discuss the application of this pump to other salts as well. We find our ocean worlds to be acidic, with a pH in the range of 2-4. We discuss and compare between the conditions found within our studied oceans and the conditions in which polyextremophiles were discovered. This work focuses on exoplanets in the super-Earth mass range (2 M_Earth), with water composing at least a few percent of their mass. Although, the principal of the desalination pump may extend beyond this mass range.
We report on a proton radiation damage experiment on P-channel CCD newly developed for an X-ray CCD camera onboard the Astro-H satellite. The device was exposed up to 10^9 protons cm^{-2} at 6.7 MeV. The charge transfer inefficiency (CTI) was measured as a function of radiation dose. In comparison with the CTI currently measured in the CCD camera onboard the Suzaku satellite for 6 years, we confirmed that the new type of P-channel CCD is radiation tolerant enough for space use. We also confirmed that a charge-injection technique and lowering the operating temperature efficiently work to reduce the CTI for our device. A comparison with other P-channel CCD experiments is also discussed.
We comment on the calculation mistake in the paper "w and w' of scalar field models of dark energy" by Takeshi Chiba [arXiv:astro-ph/0510598], where w is the dark energy equation of state and w' is the time derivative of w in units of the Hubble time. The author made a mistake while rewriting the phantom equation of motion, which led to an incorrect generic bound for the phantom model and an incorrect bound for the tracker phantom model on the w-w' plane.
This is the final and somewhat expanded version. The quality of the color photos of this version is poor as there is an upload limit on astro-ph. Much higher quality versions are available at http://space.mit.edu/~lewin/jvp.html . A bound hard copy with very high-resolution color photographs will be sent to you at request. Please send e-mail with your complete mailing address to lewin@mit.edu.
Luis P. Chimento, Alejandro S. Jakubi, Diego Pavon
In this paper we show that the claims in [Class. Quantum Grav. 19 (2002) 3067, gr-qc/0203081] related to our analysis in [Phys. Rev. D 62, 063508 (2000), astro-ph/0005070] are wrong.
Paul D. Feldman, Eric B. Burgh, Samuel T. Durrance
et al.
Far-ultraviolet spectra of Venus and Mars in the range 820-1840 A at 4 A resolution were obtained on 13 and 12 March 1995, respectively, by the Hopkins Ultraviolet Telescope (HUT), which was part of the Astro-2 observatory on the Space Shuttle Endeavour. Longward of 1250 A, the spectra of both planets are dominated by emission of the CO Fourth Positive band system and strong OI and CI multiplets. In addition, CO Hopfield-Birge bands, B - X (0,0) at 1151 A and C - X (0,0) at 1088 A, are detected for the first time, and there is a weak indication of the E - X (0,0) band at 1076 A in the spectrum of Venus. The B - X band is blended with emission from OI 1152. Modeling the relative intensities of these bands suggests that resonance fluorescence of CO is the dominant source of the emission, as it is for the Fourth Positive system. Shortward of Lyman-alpha, other emission features detected include OII 834, OI lambda 989, HI Lyman-beta, and NI 1134 and 1200. For Venus, the derived disk brightnesses of the OI, OII, and HI features are about one-half of those reported by Hord et al. (1991) from Galileo EUV measurements made in February 1990. This result is consistent with the expected variation from solar maximum to solar minimum. The ArI 1048, 1066 doublet is detected only in the spectrum of Mars and the derived mixing ratio of Ar is of the order of 2%, consistent with previous determinations.
The intra-day variable source 0917+624 displays annual changes in its timescale of variability. This is explained in terms of a scintillation model in which changes in the variability timescale are due to changes in the relative velocity of the scintillation pattern as the Earth orbits the sun. (see also astro-ph/0102050)
Yuri N. Obukhov, Vladimir A. Korotky, Friedrich W. Hehl
We point on a different possible explanation of the observations reported recently by Nodland and Ralston, PRL 78 (1997) 3043 [astro-ph/9704196]. The dipole anisotropy of the polarization of radiation from the distant radio sources can be caused by the global cosmic rotation. This explanation is of purely geometric origin and is completely within the conventional physics.
I review recent results for quasars and discuss how they are related to activity in galaxies. Topics included are studies of quasar host galaxies with HST; searches for quasars in the Hubble Deep Field; evolution of the quasar luminosity function; news highlights from astro-ph; and current observational problems and their relation to theoretical work.
A recent paper by Ahluwalia-Khalilova (astro-ph/0601489) is examined where he claims that the standard FRW cosmology with a $Λ$ predicts existence of dark matter without invoking the data on galactic rotation curves and gravitational lensing. However, we find that his claims are not correct. He has already assumed (without realizing) in the very outset what he wants to prove.