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107 result(s) for "Aleman, Isabel"
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The messy death of a multiple star system and the resulting planetary nebula as observed by JWST
Planetary nebulae—the ejected envelopes of red giant stars—provide us with a history of the last, mass-losing phases of 90% of stars initially more massive than the Sun. Here we analyse images of the planetary nebula NGC 3132 from the James Webb Space Telescope (JWST) Early Release Observations. A structured, extended hydrogen halo surrounding an ionized central bubble is imprinted with spiral structures, probably shaped by a low-mass companion orbiting the central star at about 40–60 au. The images also reveal a mid-infrared excess at the central star, interpreted as a dusty disk, which is indicative of an interaction with another closer companion. Including the previously known A-type visual companion, the progenitor of the NGC 3132 planetary nebula must have been at least a stellar quartet. The JWST images allow us to generate a model of the illumination, ionization and hydrodynamics of the molecular halo, demonstrating the power of JWST to investigate complex stellar outflows. Furthermore, new measurements of the A-type visual companion allow us to derive the value for the mass of the progenitor of a central star with excellent precision: 2.86 ± 0.06  M ⊙ . These results serve as pathfinders for future JWST observations of planetary nebulae, providing unique insight into fundamental astrophysical processes including colliding winds and binary star interactions, with implications for supernovae and gravitational-wave systems. JWST observations of the planetary nebula NGC 3132 reveal a rich molecular environment containing evidence of multiple stellar interactions on a variety of scales.
The Acacia (Vachellia nilotica (L.) P.J.H. Hurter & Mabb.): Traditional Uses and Recent Advances on Its Pharmacological Attributes and Potential Activities
For thousands of years, Vachellia nilotica has been widely used as an herbal medicine to treat some diseases and symptoms, including respiratory, gastrointestinal and urogenital ailments. The present study was adapted to document and assemble existing information about V. nilotica and its evidence-based ethnopharmacological activities, with brief reviews on the description, geographical distribution, ecology, medical uses and phytochemistry. A literature review and information up to 2024 was performed in various scientific databases, including PubMed, Science Direct and Google Scholar. The keywords were “Acacia nilotica”, “Botany”, “ecology”, “Traditional uses”, “Phytochemistry”, “Polyphenols”, “Molecular docking”, “Ethnopharmacological activities” and “toxicity”, among others. V. nilotica has a wide range of uses, with low toxicity, reported in different countries. It can be infused into oils or tea or incorporated into paste, poultice and biscuits, used as an emollient, antidiarrheal, astringent and as an antidote for bite poisons. Glucose and lipid-lowering, anti-inflammatory, analgesic, antipyretic, antioxidant, antihypertensive, antibacterial, antifungal, antiviral and anthelmintic activities are the most prominent. Over 150 chemical components have been identified from V. nilotica that could be associated with its potential actions. Quercetin, rutin, kaempferol, naringenin, catechin, epicatechin, gallic acid, ellagic acid, lupeol and niloticane are its main active constituents. From the research data, and despite the fact that human clinical trials and detailed methodological studies are scarce, V. nilotica has shown wide-ranging activities, though the most robust evidence is related to the treatment of microbial infections, diarrhea, wound and ulcer healing and for topical application. More pharmacological and toxicological studies are required to further elucidate the mechanisms of action, potential side effects, and optimal dosages for these treatments. Additionally, more clinical trials are needed to validate these traditional uses in human populations and to ensure the safety and efficacy of V. nilotica for these applications. This article offers an overview of therapeutic applications by utilizing traditional uses and recent findings on phytochemical studies, and clinical and pharmacological research.
SATELLITE: Application to Planetary Nebulae IFU Data
The integral field unit (IFU) spectroscopic view of extended ionized nebulae, such as planetary nebulae (PNe), H II regions, and galaxies, has changed the approach of studying these objects, providing a simultaneous characterization in both spatial directions. However, the spatial spaxel-by-spaxel analysis of such nebulae through IFUs is not directly comparable with the results obtained from the traditional slit-aperture spectroscopy or the predictions from 1D modelling. The new Python software called “satellite: Spectroscopic Analysis Tool for intEgraL fieLd unIt daTacubEs” is used in the analysis of the VIMOS and MUSE datacubes of four Galactic PNe. The 2D analysis of line ratio maps has shown important variations from one to another nebular component in NGC 7009 and NGC 6778. In particular, the knots in both PNe are characterized by strong emission from neutral gas that is weak or even absent from the main nebula, indicating significant variation in the ionization state and density structure among the nebular components. The far-UV radiation from the central star results in the photo-evaporation of the dense molecular knots resembling the spectrum of photodissociation regions.
Herschel Planetary Nebula Survey Plus (HerPlaNS+)
We present the current status update of the Herschel Planetary Nebula Survey Plus project (HerPlaNS+) based on the original General Observer HerPlaNS survey program during the OT1 cycle and the follow-up exhaustive archival search of PN observations using the PACS and SPIRE instruments on-board the Herschel Space Observatory.
Molecular Hydrogen Microstructures in Planetary Nebulae
Molecular hydrogen (H 2 ) emission is commonly detected in planetary nebulae (PNe), specially in objects with bipolar morphologies. New studies showed that H 2 gas is also packed in microstructures embedded in PNe of any morphological type. Despite the presence of H 2 in cometary knots being known for years, only in the last five years, much deeper imagery of PNe have revealed that H 2 also exists in other types of low-ionisation microstructures (LISs). Significant differences are found between the host PNe of cometary knots and other types of LISs, such as nebula age, central star temperature (evolutionary stage) and the absolute sizes of the microstructure itself.
WORKPLANS: Workshop on Planetary Nebula Observations
This workshop is the second of the WORKPLANS series, which we started in 2016. The main goal of WORKPLANS is to build up a network of planetary nebulae (PNe) experts to address the main open questions in the field of PNe research. The specific aims of the WORKPLANS workshop series are (i) to discuss and prioritize the most important topics to be investigated by the PN community in the following years; (ii) to establish a network of excellent researchers with complementary expertise; (iii) to formulate ambitious observing proposals for the most advanced telescopes and instrumentation presently available (ALMA, SOFIA, VLT, GTC, HST, etc.), addressing those topics; and (iv) to develop strategies for major proposals to future observatories (JWST, ELT, SPICA, Athena, etc.). To achieve these goals, WORKPLANS II brought together experts in all key sub-areas of the PNe research field, namely: analysis and interpretation of PNe observational data; theoretical modeling of gas and dust emission; evolution from Asymptotic Giant Branch stars (PNe progenitors) to PNe; and the instrumentation and technical characteristics of the relevant observatories.
PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars
Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1–3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter- and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.
PDRs4All
Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1–3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter- and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the JamesWebb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.
JWST imaging observations of the Ring Nebula
We present JWST images of NGC 6720 (the Ring Nebula), covering wavelengths from 1.6 μm to 25 μm. The bright shell is strongly fragmented with some 20 000 dense globules, bright in H2, with a characteristic diameter of 0.2 arcsec and density nH∼105–106cm−3. The shell contains a narrow ring of polycyclic aromatic hydrocarbon (PAH) emission. H2 is found throughout the shell and also in the halo. The central cavity is filled with high ionization gas and shows two linear structures seen in projection against the cavity. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (‘spikes’) extend outward from the ring, pointing away from the central star. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2–M4 dwarf. NGC 6720 is therefore a triple star system. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae.