Resultados de investigación

The physical characterization of the trans-Neptunian objects is essential for improving our understanding of the solar system's formation and evolution. Stellar occultation is a ground-based technique successfully used to determine some of the TNOs' fundamental physical properties with high precision, such as size and shape. This work aims at constraining the size, shape, and geometric albedo of the dwarf planet candidate (307261) 2002 MS4 through the analysis of nine stellar occultation events. Using multichord detection, we also studied the object's topography by analyzing the obtained limb and the residuals between observed chords and the best-fitted ellipse. We predicted and organized the observational campaigns of nine stellar occultations by 2002 MS4 between 2019 and 2022, resulting in two single-chord events, four double-chord detections, and three events with three to up to sixty-one positive chords. We derived the occultation light curves using differential aperture photometry, from which the star ingress and egress instants were calculated. Using 13 selected chords from the 8 August 2020 event, we determined the global elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the object's rotational information from the literature, constrains the object's size, shape, and albedo. Additionally, we developed a new method to characterize topography features on the object's limb. The global limb has a semi-major axis of 412+/-10km, a semi-minor axis of 385+/-17km, and the position angle of the minor axis is 121{deg}+/-16{deg}. From this instantaneous limb, we obtained 2002 MS4's geometric albedo of p_V_=0.1+/-0.025 using an H_V_=3.63+/-0.05mag and a projected area-equivalent diameter of 796+/-24km. Significant deviations from the fitted ellipse in the northernmost limb are detected from multiple sites highlighting three distinct topographic features: one 11 km depth depression followed by a 25^+4^_-5_km height elevation next to a crater-like depression with an extension of 322+/-39km and 45.1+/-1.5km deep. Our results present an object that is ~138km smaller in diameter than derived from thermal data, possibly indicating the presence of a so-far unknown satellite. However, within the error bars, the geometric albedo in the V-band agrees with the results published in the literature, even with the radiometric-derived albedo. This stellar occultation allowed for a multichord measurement of a large topography in a TNO for the first time., Tables B1, B2, and B3 contains the observational circumstances of the stations that participated in the August 8, 2020 stellar occultation campaign. Table B.1 lists the sites which obtained a positive detection, table B.2 presents the negatives, and table B.3 shows the coordinates of the stations that did not acquired data due technical failure or bad weather. Table B4 present the observational circumstances of the stations that had a positive detection on the other eight stellar occultation events recorded by the collaboration. Table B.5 presents the observers that had negatives or bad weather conditions on the another eight stellar occultation events (except 8 august 2020)., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

Samples of galaxy clusters allow us to better understand the physics at play in galaxy formation and to constrain cosmological models once their mass, position (for clustering studies) and redshift are known. In this context, large optical data sets play a crucial role. We investigate the capabilities of the Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) in detecting and characterizing galaxy groups and clusters. We analyze the data of the miniJPAS survey, obtained with the JPAS-Pathfinder camera and covering 1deg^2^ centered on the AEGIS field to the same depths and with the same 54 narrow band plus 2 broader band near-UV and near-IR filters anticipated for the full J-PAS survey. We use the Adaptive Matched Identifier of Clustered Objects (AMICO) to detect and characterize groups and clusters of galaxies down to S/N=2.5 in the redshift range 0.05, We present the galaxy groups and clusters based on the mini-JPAS data and the AMICO algorithm (Adaptive Matched Identifier of Clustered Objects). The mini-JPAS data cover an area of 1 deg2 centered on the AEGIS field to the same depths, with the same 54 narrow band plus 2 broader band near-UV and near-IR filters anticipated for the full J-PAS survey. The cluster sample is accompanied by two other catalogues, one listing the cluster members (with probabilistic associations) and listing the candidate clusters BGGs., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

The hydrogen Paschen lines are known activity indicators, but studies of them in M dwarfs during quiescence are as rare as their reports in flare studies. This situation is mostly caused by a lack of observations, owing to their location in the near-infrared regime, which is covered by few high-resolution spectrographs. We study the Pa{beta} line, using a sample of 360 M dwarfs observed by the CARMENES spectrograph. Descending the spectral sequence of inactive M stars in quiescence, we find the Pa{beta} line to get shallower until about spectral type M3.5 V, after which a slight re-deepening is observed. Looking at the whole sample, for stars with H{alpha} in absorption, we find a loose anti-correlation between the (median) pseudo-equivalent widths (pEWs) of H{alpha} and Pa{beta} for stars of similar effective temperature. Looking instead at time series of individual stars, we often find correlation between pEW(H{alpha}) and pEW(Pa{beta}) for stars with H{alpha} in emission and an anti-correlation for stars with H{alpha} in absorption. Regarding flaring activity, we report the automatic detection of 35 Paschen line flares in 20 stars. Additionally we found visually six faint Paschen line flares in these stars plus 16 faint Paschen line flares in another 12 stars. In strong flares, Paschen lines can be observed up to Pa 14. Moreover, we find that Paschen line emission is almost always coupled to symmetric H{alpha} line broadening, which we ascribe to Stark broadening, indicating high pressure in the chromosphere. Finally we report a few Pa{beta} line asymmetries for flares that also exhibit strong H{alpha} line asymmetries., The hydrogen Paschen beta, gamma, and delta lines are studied in a sample of 360 M dwarfs using CARMENES spectra by using pseudo equivalent width (pEW) measurements for a flare search. The Paschen lines are purely of chromospheric origin. We identified Pa{beta} in all stellar spectra and found, that the line gets more shallow for later spectral types with a slight re-deepening for types later than M3.5. For similar effective temperature and H{alpha} in absorption, pEW(H{alpha}) anti-correlates with pEW(Pa{beta}). We report the detection of 35 Paschen line flares in 20 stars following the thresholds for flares listed in the paper. We measure the pseudo-equivalent width (pEW) of the Pa lines in each stellar spectrum. The integration ranges for the lines and the reference bands are found in Table 1 of the paper. For comparison purposes we also measure pEW values of H{alpha}. From these measurements we compute the median pEW and the median absolute deviation (MAD) for the lines. We also list some basic stellar parameters., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

The main scientific goal of TESS is to find planets smaller than Neptune around stars that are bright enough to allow for further characterization studies. Given our current instrumentation and detection biases, M dwarfs are prime targets in the search for small planets that are in (or near) the habitable zone of their host star. In this work, we use photometric observations and CARMENES radial velocity measurements to validate a pair of transiting planet candidates found by TESS. The data were fitted simultaneously, using a Bayesian Markov chain Monte Carlo (MCMC) procedure and taking into account the stellar variability present in the photometric and spectroscopic time series. We confirm the planetary origin of the two transiting candidates orbiting around TOI-2095 (LSPM J1902+7525). The star is a nearby M dwarf (d=41.90+/-0.03pc, Teff=3759+/-87K, V=12.6mag), with a stellar mass and radius of M*=0.44+/-0.02M_{sun}_ and R*=0.44+/-0.02R_{sun}_, respectively. The planetary system is composed of two transiting planets: TOI-2095b, with an orbital period of Pb=17.66484+/-(7x10^-5^) days, and TOI-2095c, with Pc=28.17232+/-(14x10^-5^) days. Both planets have similar sizes with Rb=1.25+/-0.07R_{Earth}_ and Rc=1.33+/-0.08R_{Earth}_ for planet b and planet c, respectively. Although we did not detect the induced RV variations of any planet with significance, our CARMENES data allow us to set stringent upper limits on the masses of these objects. We find Mb<4.1M_{Earth}_ for the inner and Mc<7.4M_{Earth}_ for the outer planet (95% confidence level). These two planets present equilibrium temperatures in the range of 300-350K and are close to the inner edge of the habitable zone of their star., Radial velocity and activity indices of TOI 2095 taken with CARMENES. Spectroscopic data reduced with SERVAL., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

In the standard cosmological model of galaxy evolution, mergers and interactions play a fundamental role in shaping galaxies. Galaxies that are currently isolated are thus interesting, allowing us to distinguish between internal and external processes affecting the galactic structure. However, current observational limits may obscure crucial information in the low-mass or low-brightness regime. We use optical imaging of a subsample of the AMIGA catalogue of isolated galaxies to explore the impact of different factors on the structure of these galaxies. We study the type of disc break as a function of the degree of isolation and the presence of interaction indicators like tidal streams or plumes only detectable in the low surface brightness regime. We present deep optical imaging of a sample of 25 isolated galaxies. Through careful data processing and analysis techniques, the surface brightness limits achieved are comparable to those to be obtained on the 10-year LSST coadds. The extreme depth of our imaging allows us to study the interaction signatures of 20 galaxies, given that the presence of Galactic cirrus is a strong limiting factor in the characterisation of interactions for the remaining 5 of them. We detect previously unreported interaction features in 8 (40%) galaxies in our sample. We identify 9 galaxies (36%) showing an exponential disc (Type I), 14 galaxies (56%) with down-bending (Type II) profile and only 2 galaxies (8%) with up-bending (Type III) profiles. Isolated galaxies have considerably more purely exponential discs and fewer up-bending surface brightness profiles than field or cluster galaxies. We suggest that major mergers produce up-bending profiles while a threshold in star formation probably forms down-bending profiles. Unperturbed galaxies, evolving slowly with a low star formation rate could cause the high rate of Type I discs in isolated galaxies observed., Details of the galaxies observed, instruments used and results of the paper are presented in tables.dat. The directories included the images and profiles parameters and intensity measured for each radial bin for each of the galaxies used in the paper. Calibration values can be found in tables.dat and in the header of each profile., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

The dominant formation channel of brown dwarfs (BDs) is not well constrained yet and a promising way to discriminate between scenarios consists of testing environment-dependent efficiency in forming BDs. So far, the outcome of star formation, studied through the initial mass function, has been found to be very similar in all clusters that have been studied. We aim to characterize the low-mass (sub)stellar population of the central portion (2.4pc^2^) of the ~2Myr old cluster NGC 2244 using near-infrared spectroscopy. By studying this cluster, characterized by a low stellar density and numerous OB stars, we aim to explore the effect that OB stars may have on the production of BDs. We obtained near-infrared HK spectroscopy of 85 faint candidate members of NGC 2244. We derived the spectral type and extinction by comparison with spectral templates. We evaluated cluster membership using three gravity-sensitive spectral indices based on the shape of the H-band. Furthermore, we evaluated the infrared excess from Spitzer of all the candidate members of the cluster. Finally, we estimated the mass of all the candidate members of the cluster and derived the initial mass function, star-to-BD number ratio and disk fraction. The initial mass function is well represented by a power law (dN/dM {prop.to} M^-alpha^) below 0.4M_{sun}_, with a slope alpha=0.7-1.1 depending on the fitted mass range. We calculated a star-to-BD number ratio of 2.2-2.8. We find the low-mass population of NGC 2244 to be consistent with nearby star- forming regions, although it is at the high end of BD production. We find BDs in NGC 2244 to be, on average, closer to OB stars than to low-mass stars, which could potentially be the first piece evidence that OB stars affect the formation of BDs. We find a disk fraction of all the members with a spectral type later than K0 of 39+/-9% which is lower than typical values found in nearby star-forming regions of similar ages., KMOS/VLT spectra and parameters of 34 candidate members of NGC 2244. The data provided are the reduced, wavelength-calibrated, telluric corrected HK bands 1-d spectra. The spectra are given in fits format and are not corrected for extinction. We also provide the full list of candidate members used in this work., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

We present the completed catalog of ultradiffuse galaxy (UDG) candidates (7070 objects) from our search of the DR9 Legacy Survey images, including distance and total mass estimates for 1529 and 1436 galaxies, respectively, that we provide and describe in detail. From the sample with estimated distances, we obtain a sample of 585 UDGs ({mu}_0,g_>=24mag/arcsec^2^ and r_e_>=1.5kpc) over 20000 square degrees of sky in various environments. We conclude that UDGs in our sample are limited to 10^10^<~M_h_/M_{sun}_<~10^11.5^ and are on average a factor of 1.5-7 deficient in stars relative to the general population of galaxies of the same total mass. That factor increases with increasing galaxy size and mass up to a factor of ~10 when the total mass of the UDG increases beyond M_h_=10^11^M_{sun}_. We do not find evidence that this factor has a dependence on the UDGs large-scale environment., We report the results of our analysis of Data Release 9 (DR9) of the northern portion of the Legacy Survey, which includes observations obtained by the MOSAIC camera at the KPNO 4m telescope (MzLS, Mayall z-band Legacy Survey) and the 90Prime camera at the Steward Observatory 2.3m telescope (BASS, Beijing-Arizona Sky Survey). In addition to these telescopes, the full survey also employs DECam (DECaLS) at the CTIO 4m, which was the focus of our previous work described in Papers I-III. This paper presents our final SMUDGes catalog release, and we do not intend to reprocess data using DR10 or any future release. BASS observations were taken from 2015 November 12 to 2019 March 7 and MzLS from 2015 November 19 to 2018 February 12., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

We present RadioAstron space-based very long baseline interferometry (VLBI) observations of the nearby radio galaxy 3C84 (NGC1275) at the centre of the Perseus cluster. The observations were carried out during a perigee passage of the Spektr-R spacecraft on September 21-22, 2013 and involved a global array of 24 ground radio telescopes observing at 5GHz and 22GHz, together with the Space Radio Telescope (SRT). Furthermore, the Very Long Baseline Array (VLBA) and the phased Very Large Array (VLA) observed the source quasi-simultaneously at 15 GHz and 43 GHz. Fringes between the ground array and the SRT were detected on baseline lengths up to 8.1 times the Earth's diameter, providing unprecedented resolution for 3C 84 at these wavelengths. We note that the corresponding fringe spacing is 125uas at 5GHz and 27uas at 22GHz. Our space-VLBI images reveal a previously unseen sub- structure inside the compact ~1pc long jet that was ejected about ten years earlier. In the 5GHz image, we detected, for the first time, low-intensity emission from a cocoon-like structure around the restarted jet. Our results suggest that the increased power of the young jet is inflating a bubble of hot plasma as it carves its way through the ambient medium of the central region of the galaxy. Here, we estimate the minimum energy stored in the mini-cocoon, along with its pressure, volume, expansion speed, and the ratio of heavy particles to relativistic electrons, as well as the density of the ambient medium. About half of the energy delivered by the jet is dumped into the mini-cocoon and the quasi-spherical shape of the bubble suggests that this energy may be transferred to a significantly larger volume of the interstellar medium than what would be accomplished by the well-collimated jet on its own. The pressure of the hot mini-cocoon also provides a natural explanation for the almost cylindrical jet profile seen in the 22GHz RadioAstron image., Space-VLBI and global-VLBI CLEAN images of 3C84 in FITS format. The observations were made on 21-09-2013 and comprised four frequency bands: 5GHz and 22GHz with RadioAstron space-VLBI satellite together with a global VLBI ground array and 15GHz and 43GHz with the Very Long Baseline Array together with the Very Large Array. The FITS files include CLEAN images from several different (u,v) weighting schemes and using several different restoring beam sizes. These data were observed as a part of the RadioAstron Nearby AGN Key Science program (global VLBI project code GS032A)., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

Massive stars have an impact on their surroundings from early in their formation until the end of their lives. However, very little is known about their formation. Episodic accretion may play a crucial role in the process, but only a handful of observations have reported such events occurring in massive protostars. We aim to investigate the outburst event from the high-mass star-forming region S255IR where the protostar NIRS3 recently underwent an accretion outburst. We follow the evolution of this source both in photometry and morphology of its surroundings. We performed near infrared adaptive optics observations on the S255IR central region using the Large Binocular Telescope in the Ks broadband as well as the H_2_ and Br{gamma} narrow-band filters with an angular resolution of ~0.06arcsec, close to the diffraction limit. We discovered a new near infrared knot north-east of NIRS3 that we interpret as a jet knot that was ejected during the last accretion outburst and observed in the radio regime as part of a follow-up after the outburst. We measured a mean tangential velocity for this knot of 450+/-50km/s. We analysed the continuum-subtracted images from H_2_, which traces jet-shocked emission, and Br{gamma}, which traces scattered light from a combination of accretion activity and UV radiation from the central massive protostar. We observed a significant decrease in flux at the location of NIRS3, with K=13.48mag being the absolute minimum in the historic series. Our observations strongly suggest a scenario where the episodic accretion is followed by an episodic ejection response in the near infrared, as was seen in the earlier radio follow-up. The ~2um photometry from the past 30 years suggests that NIRS3 might have undergone another outburst in the late 1980s, making it the first massive protostar with such evidence observed in the near infrared., Reduced images from the Large Binocular Telescope (LBT) of the S255IR massive star-forming region. Below we give further details extracted from text in the paper. Observations were taken on 13 February 2022 with the Large Binocular Telescope (LBT), in particular the SX telescope with an 8.4m primary mirror and using the LBT Utility Camera in the Infrared (LUCI) instrument (programme ID: UV-2022A-004, PI: J.C. Tan). Adaptive optics assisted mode was used with the Single conjugated adaptive Optics Upgrade for LBT SOUL (Pinna et al., 2016, in Adaptive Optics Systems V, ed. E. Marchetti, L. M. Close, & J.-P. Veran, Vol. 9909, International Society for Optics and Photonics (SPIE), 99093V). The N30 camera with a pixel scale of 0.015arcsec and field of view (FoV) of 30arcsec*30arcsec was used. The filters Ks, H_2_), and Br{gamma}, which are centred at the wavelengths 2.163, 2.124, 2.170um, respectively, were employed. Images were centred around S255IR NIRS3, with central coordinates of the image RA(J2000)=06:12:54.355, Dec(J2000)=+17:59:23.748. The AO guide star we used (i.e. 2MASSJ06125505+1759289 RA(J2000)=06:12:55.049, Dec(J2000)=+17:59:28.896, R=14.8mag) is located 14arcsec from NIRS3. The Strehl ratio was 0.2, and the final full width half maximum (FWHM) at the position of the AO guide star was ~0.06arcsec for all three filters (derived by fitting Moffat profiles, namely, close to the LBT diffraction limit. The data were reduced and flux calibrated with custom Python scripts using the Python packages ccdproc, astropy and photutils. The flux calibration was performed by matching field stars with the UKIRT Infrared Deep Sky Survey (UKIDSS) point source catalogue, for which we achieved an accuracy of ~0.06mag. The data were astrometrically corrected by matching stars to the Gaia DR3 catalogue retrieved with astroquery. We were able to match seven Gaia stars in our FoV and have a final residual for the astrometry of 0.034arcsec., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No

We present a new image of a 26.5 square degree region in the Bootes constellation obtained at 1.4GHz using the Aperture Tile in Focus (Apertif) system on the Westerbork Synthesis Radio Telescope. We use a newly developed processing pipeline which includes direction-dependent self-calibration which provides a significant improvement of the quality of the images compared to those released as part of the Apertif first data release. For the Bootes region, we mosaic 187 Apertif images and extract a source catalog. The mosaic image has an angular resolution of 27x11.5 arcsec and a median background noise of 40uJy/beam. The catalog has 8994 sources and is complete down to the 0.3mJy level. We combine the Apertif image with LOFAR images of the Bootes field at 54 and 150MHz to study spectral properties of the sources. We find a spectral flattening towards low flux density sources. Using the spectral index limits from Apertif non-detections we derive that up to 9% of the sources have ultra-steep spectra with a slope steeper than -1.2. Steepening of the spectral index with increasing redshift is also seen in the data showing a different dependency for the low-frequency spectral index and the high frequency one. This can be explained by a population of sources having concave radio spectra with a turnover frequency around the LOFAR band. Additionally, we discuss cases of individual extended sources with an interesting resolved spectral structure. With the improved pipeline, we aim to continue processing data from the Apertif wide-area surveys and release the improved 1.4GHz images of several famous fields., We extracted the Apertif source catalog using the Python Blob Detector and Source Finder (PyBDSF; Mohan & Rafferty 2015). Similar to Shimwell et al. (2019A&A...622A...1S, Cat. J/A+A/622/A1), we used a peak and island detection threshold of 5{sigma} and 4{sigma} respectively, and the size of a sliding box to estimate the local RMS was set to 30x30xbmaj, where bmaj is the major axis of the synthesized beam. We used the publicly available LOFAR HBA and LBA mosaic images and the corresponding catalogs of the Bootes area (Tasse et al. 2021A&A...648A...1T; Williams et al. 2021A&A...655A..40W, Cat. J/A+A/655/A40) and present spectral indices of the sources in table3., Financial support from the Severo Ochoa grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033, No