Issue Title: Magnetic Fields and Star Foramtion: Theory Versus Observations (Guest Editor: A.I. Gómez de Castro, M. Heyer, E. Vázquez-Semadeni, R. Rrebolo, M. Tagger and R.E. Pudritz) We have ...monitored S Ori 45, a young, low-mass (20 M ^sub j^ up) brown dwarf of the σ Orionis cluster (3 Myr, 352 pc), using optical and near-infrared filters. S Ori 45 (spectral type M8.5) is found to be multi-periodic with a dominant modulation at 2.5-3.5 h, and a short modulation at about 46 min. We ascribe the longer of these modulations to a rotation period. After comparing these results with observations of more massive cluster brown dwarfs and field brown dwarfs, we conclude that substellar objects present rotational and angular momentum evolution. We have also obtained intermediate-resolution near-infrared spectroscopy of S Ori 70, which is a T-class, free-floating planetary candidate member in the σ Orionis cluster. Its observed spectrum has been compared to data of field brown dwarfs of similar types and to theoretical spectra computed for different surface temperatures and gravities. We conclude that S Ori 70 has a significantly cool, low-gravity atmosphere. This supports the young age of this object and its membership in the cluster. From state-of-the-art evolutionary models, the mass of S Ori 70 is estimated at 3 times the Jovian mass (^sup +5^ ^sub -2^ M ^sub j^ up), challenging current stellar/substellar formation models. S Ori 70 remains the lowest mass object so far identified in any open cluster.PUBLICATION ABSTRACT
In a search for common proper motion companions using the VISTA Hemisphere Survey and 2MASS catalogs we have identified a very red (J-Ks=2.47 mag) late-L dwarf companion of a previously unrecognized ...M dwarf VHS J125601.92-125723.9, located at a projected angular separation of 8.06"+/-0.03". From low-resolution optical and near-IR spectroscopy we classified the primary and the companion as an M7.5+/-0.5 and L7+/-1.5, respectively. The primary shows weaker alkali lines than field dwarfs of similar spectral type, but still consistent with either a high-gravity dwarf or a younger object of hundreds of millions of years. The secondary shows spectral features characteristic for low surface gravity objects at ages below several hundred Myr, like the triangular shape of the H-band continuum and alkali lines weaker than in field dwarfs of the same spectral type. The absence of lithium in the atmosphere of the primary and the likely membership to the Local Association allowed us to constrain the age of the system to the range of 150-300 Myr. We report a measurement of the trigonometric parallax pi=78.8+/-6.4 mas, which translates into a distance of 12.7+/-1.0 pc; the pair thus has a projected physical separation of 102+/-9 AU. We derived the Lbol of the components and compared them with theoretical evolutionary models to estimate the masses and effective temperatures. For the primary, we determined log(Lbol/LSun)=-3.14+/-0.10, and a mass of 73 (+20,-15} MJup at the boundary between stars and brown dwarfs and Teff of 2620+/-140 K. For the companion we obtained log(Lbol/LSun)=-5.05+/-0.22 and a mass of 11.2 (+9.7,-1.8) MJup placing it near the deuterium-burning mass limit. The effective temperature derived from evolutionary models is 880 (+140,-110) K, about 400-700 K cooler than expected for field late-L dwarfs.
(Abridged) We characterize a series of neutral vanadium atomic absorption lines in the 800--910nm wavelength region of high signal-to-noise, high-resolution, telluric-corrected M-dwarf spectra from ...the CARMENES survey. Many of these lines are prominent and exhibit a distinctive broad and flat-bottom shape, which is a result of hyperfine structure (HFS). We investigate the potential and implications of these HFS split lines for abundance analysis of cool stars. With standard spectral synthesis routines, as provided by the spectroscopy software iSpec and the latest atomic data (including HFS) available from the VALD3 database, we modeled these striking line profiles. We used them to measure V abundances of cool dwarfs. We determined V abundances for 135 early M dwarfs (M0.0V to M3.5V) in the CARMENES guaranteed time observations sample. They exhibit a V/Fe-Fe/H trend consistent with that derived from nearby FG dwarfs. The tight (\(\pm\) 0.1 dex) correlation between V/H and Fe/H suggests the potential application of V as an alternative metallicity indicator in M dwarfs. We also show hints that neglecting to model HFS could partially explain the temperature correlation in V abundance measurements observed in previous studies of samples involving dwarf stars with \(T_{\rm eff} \lesssim 5300\)K. Our work suggests that HFS can impact certain absorption lines in cool photospheres more severely than in Sun-like ones. Therefore, we advocate that HFS should be carefully treated in abundance studies in stars cooler than \(\sim 5000\)K. On the other hand, strong HFS split lines in high-resolution spectra present an opportunity for precision chemical analyses of large samples of cool stars. The V-to-Fe trends exhibited by the local M dwarfs continue to challenge theoretical models of V production in the Galaxy.
White Paper on MAAT@GTC Prada, Francisco; Content, Robert; Goobar, Ariel ...
arXiv.org,
07/2020
Paper, Journal Article
Odprti dostop
MAAT is proposed as a visitor mirror-slicer optical system that will allow the OSIRIS spectrograph on the 10.4-m Gran telescopio CANARIAS (GTC) the capability to perform Integral Field Spectroscopy ...(IFS) over a seeing-limited FoV 14.20''x10'' with a slice width of 0.303''. MAAT@GTC will enhance the resolution power of OSIRIS by 1.6 times as compared to its 0.6'' wide long-slit. All the eleven OSIRIS grisms and volume-phase holographic gratings will be available to provide broad spectral coverage with moderate resolution (R=600 up to 4100) in the 3600 - 10000 Å wavelength range. MAAT unique observing capabilities will broaden its use to the needs of the GTC community to unveil the nature of most striking phenomena in the universe well beyond time-domain astronomy. The GTC equipped with OSIRIS+MAAT will also play a fundamental role in synergy with other facilities, some of them operating on the northern ORM at La Palma. This White Paper presents the different aspects of MAAT@GTC - including scientific and technical specifications, outstanding science cases, and an outline of the instrument concept.
Cancer development is a complex process driven by inherited and acquired molecular and cellular alterations. Prevention is the holy grail of cancer elimination, but making this a reality will take a ...fundamental rethinking and deep understanding of premalignant biology. In this Perspective, we propose a national concerted effort to create a Precancer Atlas (PCA), integrating multi-omics and immunity - basic tenets of the neoplastic process. The biology of neoplasia caused by germline mutations has led to paradigm-changing precision prevention efforts, including: tumor testing for mismatch repair (MMR) deficiency in Lynch syndrome establishing a new paradigm, combinatorial chemoprevention efficacy in familial adenomatous polyposis (FAP), signal of benefit from imaging-based early detection research in high-germline risk for pancreatic neoplasia, elucidating early ontogeny in
-mutation carriers leading to an international breast cancer prevention trial, and insights into the intricate germline-somatic-immunity interaction landscape. Emerging genetic and pharmacologic (metformin) disruption of mitochondrial (mt) respiration increased autophagy to prevent cancer in a Li-Fraumeni mouse model (biology reproduced in clinical pilot) and revealed profound influences of subtle changes in mt DNA background variation on obesity, aging, and cancer risk. The elaborate communication between the immune system and neoplasia includes an increasingly complex cellular microenvironment and dynamic interactions between host genetics, environmental factors, and microbes in shaping the immune response. Cancer vaccines are in early murine and clinical precancer studies, building on the recent successes of immunotherapy and HPV vaccine immune prevention. Molecular monitoring in Barrett's esophagus to avoid overdiagnosis/treatment highlights an important PCA theme. Next generation sequencing (NGS) discovered age-related clonal hematopoiesis of indeterminate potential (CHIP). Ultra-deep NGS reports over the past year have redefined the premalignant landscape remarkably identifying tiny clones in the blood of up to 95% of women in their 50s, suggesting that potentially premalignant clones are ubiquitous. Similar data from eyelid skin and peritoneal and uterine lavage fluid provide unprecedented opportunities to dissect the earliest phases of stem/progenitor clonal (and microenvironment) evolution/diversity with new single-cell and liquid biopsy technologies. Cancer mutational signatures reflect exogenous or endogenous processes imprinted over time in precursors. Accelerating the prevention of cancer will require a large-scale, longitudinal effort, leveraging diverse disciplines (from genetics, biochemistry, and immunology to mathematics, computational biology, and engineering), initiatives, technologies, and models in developing an integrated multi-omics and immunity PCA - an immense national resource to interrogate, target, and intercept events that drive oncogenesis.
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Cancer is a rapidly evolving, multifactorial disease that accumulates numerous genetic and epigenetic alterations. This results in molecular and phenotypic heterogeneity within the tumor, the ...complexity of which is further amplified through specific interactions between cancer cells. We aimed to dissect the molecular mechanisms underlying the cooperation between different clones.
We produced clonal cell lines derived from the MDA-MB-231 breast cancer cell line, using the UbC-StarTrack system, which allowed tracking of multiple clones by color: GFP C3, mKO E10 and Sapphire D7. Characterization of these clones was performed by growth rate, cell metabolic activity, wound healing, invasion assays and genetic and epigenetic arrays. Tumorigenicity was tested by orthotopic and intravenous injections. Clonal cooperation was evaluated by medium complementation, co-culture and co-injection assays.
Characterization of these clones in vitro revealed clear genetic and epigenetic differences that affected growth rate, cell metabolic activity, morphology and cytokine expression among cell lines. In vivo, all clonal cell lines were able to form tumors; however, injection of an equal mix of the different clones led to tumors with very few mKO E10 cells. Additionally, the mKO E10 clonal cell line showed a significant inability to form lung metastases. These results confirm that even in stable cell lines heterogeneity is present. In vitro, the complementation of growth medium with medium or exosomes from parental or clonal cell lines increased the growth rate of the other clones. Complementation assays, co-growth and co-injection of mKO E10 and GFP C3 clonal cell lines increased the efficiency of invasion and migration.
These findings support a model where interplay between clones confers aggressiveness, and which may allow identification of the factors involved in cellular communication that could play a role in clonal cooperation and thus represent new targets for preventing tumor progression.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
J. of Astronomical Telescopes, Instruments, and Systems, 5(1),
015001 (2018) We report the development of a 4-color simultaneous camera for the 1.52~m
Telescopio Carlos S\'anchez (TCS) in the Teide ...Observatory, Canaries, Spain.
The new instrument, named MuSCAT2, has a capability of 4-color simultaneous
imaging in $g$ (400--550 nm), $r$ (550--700 nm), $i$ (700--820 nm), and $z_s$
(820--920 nm) bands. MuSCAT2 equips four 1024$\times$1024 pixel CCDs, having a
field of view of 7.4$\times$7.4 arcmin$^2$ with a pixel scale of 0.44 arcsec
per pixel. The principal purpose of MuSCAT2 is to perform high-precision
multi-color exoplanet transit photometry. We have demonstrated photometric
precisions of 0.057%, 0.050%, 0.060%, and 0.076% as root-mean-square residuals
of 60~s binning in $g$, $r$, $i$ and $z_s$ bands, respectively, for a G0 V star
WASP-12 ($V=11.57\pm0.16$). MuSCAT2 has started science operations since
January 2018, with over 250 telescope nights per year. MuSCAT2 is expected to
become a reference tool for exoplanet transit observations, and will
substantially contribute to the follow-up of the TESS and PLATO space missions.
The ESA space mission Euclid was launched on July 1st, 2023 and is undergoing its science verification phase. In this invited review we show that Euclid means a before and an after for our ...understanding of ultra-cool dwarfs and substellar-mass objects and their connections with stars, exoplanets and the Milky Way. Euclid enables the study with unprecedented statistical significance a very large ensemble of ultracool dwarfs, the identification of new types of substellar objects, and the determination of the substellar binary fraction and the Initial Mass Function (IMF) in diverse galactic environments from the nearest stellar nurseries to the ancient relics of Galactic formation.
We report on Doppler observations of three transiting planet candidates that were detected during Campaign 1 of the K2 mission. The Doppler observations were conducted with FIES, HARPS-N and HARPS. ...We measure the mass of K2-27b (EPIC 201546283b), and provide constraints and upper limits for EPIC 201295312b and EPIC 201577035b. K2-27b is a warm Neptune orbiting its host star in 6.77 days and has a radius of \(4.45^{+0.33}_{-0.33}~\mathrm{R_\oplus}\) and a mass of \(29.1^{+7.5}_{-7.4}~\mathrm{M_\oplus}\), which leads to a mean density of \(1.80^{+0.70}_{-0.55}~\mathrm{g~cm^{-3}}\). EPIC 201295312b is smaller than Neptune with an orbital period of 5.66 days, radius \(2.75^{+0.24}_{-0.22}~\mathrm{R_\oplus}\) and we constrain the mass to be below \(12~\mathrm{M_\oplus}\) at 95% confidence. We also find a long-term trend indicative of another body in the system. EPIC 201577035b, previously confirmed as the planet K2-10b, is smaller than Neptune orbiting its host star in 19.3 days, with radius \(3.84^{+0.35}_{-0.34}~\mathrm{R_\oplus}\). We determine its mass to be \(27^{+17}_{-16}~\mathrm{M_\oplus}\), with a 95% confidence uppler limit at \(57~\mathrm{M_\oplus}\), and mean density \(2.6^{+2.1}_{-1.6}~{\rm g~cm}^{-3}\). These measurements join the relatively small collection of planets smaller than Neptune with measurements or constraints of the mean density. Our code for performing K2 photometry and detecting planetary transits is now publicly available.
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