66 research outputs found
Space education activities at the Romanian Science Festival
Eastern European countries, in particular Romania, offer much fewer opportunities for science and space outreach and informal science education compared to the West. Romanian Science Festival was founded in 2018 with the aim of answering questions raised by the inquisitive minds of children all over Romania. In 2019, we reached over 20,000 people with our live events: open-air science festivals, space talks and astronomical observations. During the COVID-19 pandemic, we organised 58 live webinars of over 75 hours in total, one of the largest scientific resources in the Romanian language. Moreover, we visited 150 schools across the country, including rural areas, providing an opportunity for students to meet scientists online. Space-related topics are a key focus of the science festival as they are not included in the Romanian school curriculum. That is why the resources in the form of the expertise and career orientation offered by our mentors are so valuable to the students. The topics we address include Astronomy (asteroids, black holes, extrasolar planets, etc.), Space Exploration, Satellite Design and Earth Observations. In 2021 and 2022 we organised the âSpace monthâ during which thousands of students had the opportunity to discover careers in space, participate in competitions, meet the only Romanian astronaut, Dumitru Prunariu, in celebrations of 40 yearsâ of his space flight and a former NASA director of Astrophysics. Through mentorship, students discover opportunities to study and do research in astronomy. All these activities expose the public to the latest discoveries in the field, thus highlighting the importance of investing in fundamental research. This is just the beginning. The Romanian Science Festival story will continue because our team is determined to create a systemic impact in education. We will continue to add new chapters, stimulating the curiosity and imagination of people fascinated by science and space
Hubble Asteroid Hunter: II. Identifying strong gravitational lenses in HST images with crowdsourcing
The Hubble Space Telescope (HST) archives constitute a rich dataset of high
resolution images to mine for strong gravitational lenses. While many HST
programs specifically target strong lenses, they can also be present by
coincidence in other HST observations. We aim to identify non-targeted strong
gravitational lenses in almost two decades of images from the ESA it Hubble
Space Telescope archive (eHST), without any prior selection on the lens
properties. We used crowdsourcing on the Hubble Asteroid Hunter (HAH) citizen
science project to identify strong lenses, alongside asteroid trails, in
publicly available large field-of-view HST images. We visually inspected 2354
objects tagged by citizen scientists as strong lenses to clean the sample and
identify the genuine lenses. We report the detection of 252 strong
gravitational lens candidates, which were not the primary targets of the HST
observations. 198 of them are new, not previously reported by other studies,
consisting of 45 A grades, 74 B grades and 79 C grades. The majority are
galaxy-galaxy configurations. The newly detected lenses are, on average, 1.3
magnitudes fainter than previous HST searches. This sample of strong lenses
with high resolution HST imaging is ideal to follow-up with spectroscopy, for
lens modelling and scientific analyses. This paper presents an unbiased search
of lenses, which enabled us to find a high variety of lens configurations,
including exotic lenses. We demonstrate the power of crowdsourcing in visually
identifying strong lenses and the benefits of exploring large archival
datasets. This study shows the potential of using crowdsourcing in combination
with artificial intelligence for the detection and validation of strong lenses
in future large-scale surveys such as ESA's future mission Euclid or in JWST
archival images.Comment: 24 page, 14 figures, 5 tables, accepted for publication in A&A June
28 202
Asteroids seen by JWST-MIRI: Radiometric size, distance, and orbit constraints
Infrared measurements of asteroids are crucial for the determination of physical and thermal properties of individual objects, and for understanding the small-body populations in the solar system as a whole. However, standard radiometric methods can only be applied if the orbit of an object is known, hence its position at the time of the observation. With JWST-MIRI observations the situation will change and many unknown, often very small, solar system objects will be detected. Later orbit determinations are difficult due to the faintness of the objects and the lack of dedicated follow-up concepts. We present MIRI observations of the outer-belt asteroid (10920) 1998 BC1 and an unknown object, detected in all nine MIRI bands in close apparent proximity to (10920). We developed a new method called STM-ORBIT to interpret the multi-band measurements without knowing the objectâs true location. The power of the new technique is that it determines the most-likely heliocentric and observer-centric distance and phase angle ranges, allowing us to make a radiometric size estimate. The application to the MIRI fluxes of (10920) was used to validate the method. It leads to a confirmation of the known radiometric size-albedo solution, and puts constraints on the asteroidâs location and orbit in agreement with its true orbit. To back up the validation of the method, we obtained additional ground-based light curve observations of (10920), combined with Gaia data, which indicate a very elongated object (a/b â„ 1.5), with a spin-pole at (λ, ÎČ)ecl = (178°, +81°), with an estimated error of about 20°, and a rotation period of 4.861191 ± 0.000015 h. A thermophysical study of all available JWST-MIRI and WISE measurements leads to a size of 14.5â16.5 km (diameter of an equal-volume sphere), a geometric albedo pV between 0.05 and 0.10, and a thermal inertia in the range 9â35 (best value 15) J mâ2 sâ0.5 Kâ1. For the newly discovered MIRI object, the STM-ORBIT method revealed a size of 100â230 m. The new asteroid must be on a low-inclination orbit (0.7° < i < 2.0°) and it was located in the inner main-belt region during JWST observations. A beaming parameter η larger than 1.0 would push the size even below 100 meters, a main-belt regime that has escaped IR detections so far. This kind of MIRI observations can therefore contribute to formation and evolution studies via classical size-frequency studies, which are currently limited to objects larger than about one kilometer in size. We estimate that MIRI frames with pointings close to the ecliptic and short integration times of only a few seconds will always include a few asteroids; most of them will be unknown objects.TSR acknowledges funding from the NEO-MAPP project (H2020-EU-2-1-6/870377). This work was (partially) funded by the Spanish MICIN/AEI/10.13039/501100011033 and by âERDF A way of making Europeâ by the European Union through grant RTI2018-095076-B-C21, and the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia âMarĂa de Maeztuâ) through grant CEX2019-000918-M. PPB acknowledges funding through the Spanish Government retraining plan âMarĂa Zambrano 2021-2023â at the University of Alicante (ZAMBRANO22-04)
Revealing the cosmic evolution of boxy/peanut-shaped bulges from HST COSMOS and SDSS
Abstract Vertically thickened bars, observed in the form of boxy/peanut (B/P) bulges, are found in the majority of massive barred disc galaxies in the local Universe, including our own. B/P bulges indicate that their host bars have suffered violent bending instabilities driven by anisotropic velocity distributions. We investigate for the first time how the frequency of B/P bulges in barred galaxies evolves from z = 1 to z â 0, using a large sample of non-edge-on galaxies with masses Mâ > 1010 Mâ, selected from the HST COSMOS survey. We find the observed fraction increases from at z = 1 to % at z = 0.2. We account for problems identifying B/P bulges in galaxies with low inclinations and unfavourable bar orientations, and due to redshift-dependent observational biases with the help of a sample from the Sloan Digital Sky Survey, matched in resolution, rest-frame band, signal-to-noise ratio and stellar mass and analysed in the same fashion. From this, we estimate that the true fraction of barred galaxies with B/P bulges increases from âŒ10% at z â 1 to at z = 0. In agreement with previous results for nearby galaxies, we find a strong dependence of the presence of a B/P bulge on galaxy stellar mass. This trend is observed in both local and high-redshift galaxies, indicating that it is an important indicator of vertical instabilities across a large fraction of the age of the Universe. We propose that galaxy formation processes regulate the thickness of galaxy discs, which in turn affect which galaxies experience violent bending instabilities of the bar
The Loneliest Galaxies in the Universe: A GAMA and GalaxyZoo Study on Void Galaxy Morphology
The large-scale structure (LSS) of the Universe is comprised of galaxy
filaments, tendrils, and voids. The majority of the Universe's volume is taken
up by these voids, which exist as underdense, but not empty, regions. The
galaxies found inside these voids are expected to be some of the most isolated
objects in the Universe. This study, using the Galaxy and Mass Assembly (GAMA)
and Galaxy Zoo surveys, aims to investigate basic physical properties and
morphology of void galaxies versus field (filament and tendril) galaxies. We
use void galaxies with stellar masses of , and
this sample is split by identifying two redshift-limited regions, 0 < z <
0.075, and, . To find comparable objects in the sample of
field galaxies from GAMA and Galaxy Zoo, we identify "twins" of void galaxies
as field galaxies within 0.05 dex and 0.15 dex of M and specific star
formation rate. We determine the statistical significance of our results using
the Kolmogorov-Smirnov (KS) test. We see that void galaxies, in contrast with
field galaxies, seem to be disk-dominated and have predominantly round bulges
(with > 50 percent of the Galaxy Zoo citizen scientists agreeing that bulges
are present).Comment: 13 pages, 16 figures, 3 tables, accepted by MNRA
Galaxy Zoo: constraining the origin of spiral arms
Since the discovery that the majority of low-redshift galaxies exhibit some level of spiral structure, a number of theories have been proposed as to why these patterns exist. A popular explanation is a process known as swing amplification, yet there is no observational evidence to prove that such a mechanism is at play. By using a number of measured properties of galaxies, and scaling relations where there are no direct measurements, we model samples of SDSS and S4G spiral galaxies in terms of their relative halo, bulge and disc mass and size. Using these models, we test predictions of swing amplification theory with respect to directly measured spiral arm numbers from Galaxy Zoo 2. We find that neither a universal cored or cuspy inner dark matter profile can correctly predict observed numbers of arms in galaxies. However, by invoking a halo contraction/expansion model, a clear bimodality in the spiral galaxy population emerges. Approximately 40 per cent of unbarred spiral galaxies at z 10^10 Msolar have spiral arms that can be modelled by swing amplification. This population display a significant correlation between predicted and observed spiral arm numbers, evidence that they are swing amplified modes. The remainder are dominated by two-arm systems for which the model predicts significantly higher arm numbers. These are likely driven by tidal interactions or other mechanisms
Galaxy Zoo: star formation versus spiral arm number
Spiral arms are common features in low-redshift disc galaxies, and are prominent sites of star formation and dust obscuration. However, spiral structure can take many forms: from galaxies displaying two strong âgrand designâ arms to those with many âflocculentâ arms. We investigate how these different arm types are related to a galaxy's star formation and gas properties by making use of visual spiral arm number measurements from Galaxy Zoo 2. We combine ultraviolet and mid-infrared (MIR) photometry from GALEX and WISE to measure the rates and relative fractions of obscured and unobscured star formation in a sample of low-redshift SDSS spirals. Total star formation rate has little dependence on spiral arm multiplicity, but two-armed spirals convert their gas to stars more efficiently. We find significant differences in the fraction of obscured star formation: an additional âŒ10 per cent of star formation in two-armed galaxies is identified via MIR dust emission, compared to that in many-armed galaxies. The latter are also significantly offset below the IRXâÎČ relation for low-redshift star-forming galaxies. We present several explanations for these differences versus arm number: variations in the spatial distribution, sizes or clearing time-scales of star-forming regions (i.e. molecular clouds), or contrasting recent star formation histories
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