Kojima-1Lb is a mildly cold neptune around the brightest microlensing host star

We report the analysis of additional multiband photometry and spectroscopy and new adaptive optics (AO) imaging of the nearby planetary microlensing event TCPJ05074264+2447555 (Kojima-1), which was discovered toward the Galactic anticenter in 2017 (Nucita et al.). We confirm the planetary nature of the light-curve anomaly around the peak while finding no additional planetary feature in this event. We also confirm the presence of apparent blending flux and the absence of significant parallax signal reported in the literature. The AO image reveals no contaminating sources, making it most likely that the blending flux comes from the lens star. The measured multiband lens flux, combined with a constraint from the microlensing model, allows us to narrow down the previously unresolved mass and distance of the lens system. We find that the primary lens is a dwarf on the K/M boundary (0.581 ± 0.033Me) located at 505±47 pc, and the companion (Kojima-1Lb) is a Neptune-mass planet (20.0 ± 2.0M⊕) with a semimajor axis of-1.08+0.18 0.62 au. This orbit is a few times smaller than those of typical microlensing planets and is comparable to the snow-line location at young ages. We calculate that the a priori detection probability of Kojima-1Lb is only ∼35%, which may imply that Neptunes are common around the snow line, as recently suggested by the transit and radial velocity techniques. The host star is the brightest among the microlensing planetary systems (Ks = 13.7), offering a great opportunity to spectroscopically characterize this system, even with current facilities

Collider aspects of flavour physics at high Q

This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard Model, such as supersymmetry, little Higgs model or models with extra dimensions. This includes discovery aspects as well as measurement of several properties of these heavy states. We also present public available computational tools related to this topic.Comment: Report of Working Group 1 of the CERN Workshop ``Flavour in the era of the LHC'', Geneva, Switzerland, November 2005 -- March 200

The Least Massive (Sub)Stellar Component Of The Milky Way

This review presents a panorama of the research topics that are currently being developed by our strategic research group at the IAC in the field of very low-mass stars, brown dwarfs, extrasolar giant planets and the solar system. Our main goal is to investigate the cosmogony of the least massive stellar and substellar component of the Milky Way. We are using multiwavelength observations and theoretical modeling to provide constrains to different scenarios of star and planet formation. We present summaries of the following results: (1) the study of a deeply-embedded low-mass protostar in the B59 molecular cloud; (2) the discovery of accreting very low-mass objects in the IPHAS survey; (3) the identification of faint planetary-mass candidates in the cores of young open clusters using multiconjugate adaptive optics; (4) the discovery of a widely separated companion of a young brown dwarf; (5) the search for reflected light from hot Jupiters; and (6) the spectroscopic study of relics of the formation of our Solar System. © Springer-Verlag Berlin Heidelberg 2010

The Substellar Mass Function In Σ Orionis Ii. Optical, Near-Infrared And Irac/Spitzer Photometry Of Young Cluster Brown Dwarfs And Planetary-Mass Objects

Aims. We investigate the mass function in the substellar domain down to a few Jupiter masses in the young σ Orionis open cluster (3 ± 2 Ma, d = 360-60+70 pc). Methods. We have performed a deep IJ-band search, covering an area of 790 arcmin2 close to the cluster centre. This survey was complemented with an infrared follow-up in the HK s- and Spitzer 3.6-8.0 μm-bands. Using colour-magnitude diagrams, we have selected 49 candidate cluster members in the magnitude interval 16.1 mag \u3c I \u3c 23.0 mag. Results. Accounting for flux excesses at 8.0 μm and previously known spectral features of youth, we identify 30 objects as bona fide cluster members. Four are first identified from our optical-near infrared data. Eleven have most probable masses below the deuterium burning limit which we therefore classify as candidate planetary-mass objects. The slope of the substellar mass spectrum (ΔN/ΔM ≈ aM-α) in the mass interval 0.11 M⊙ \u3c M \u3c 0.006 M⊙ is α = +0.6 ± 0.2. Any mass limit to formation via opacity-limited fragmentation must lie below 0.006 M⊙. The frequency of σ Orionis brown dwarfs with circumsubstellar discs is 47±9 %. Conclusions. The continuity in the mass function and in the frequency of discs suggests that very low-mass stars and substellar objects, even below the deuterium-burning mass limit, share the same formation mechanism. © ESO 2007

New Constraints On The Membership Of The T Dwarf S Ori 70 In The Σ Orionis Cluster

Aims.The nature of S Ori 70 (S Ori J053810.1-023626), a faint mid-T type object found towards the direction of the young Orionis cluster, is still under debate. We intend to find out whether it is a field brown dwarf or a 3-Myr old planetary-mass member of the cluster.Methods.We report on near-infrared and mid-infrared [3.6] and [4.5] IRAC/Spitzer photometry recently obtained for S Ori 70. The new near-infrared images (taken 3.82 yr after the discovery data) allowed us to derive the first proper motion measurement for this object. Results.The colors (H - Ks), (J - Ks) and Ks - [3.6] appear discrepant when compared to T4-T7 dwarfs in the field. This behavior could be ascribed either to a low-gravity atmosphere or to an atmosphere with a metallicity that is significantly different than solar. The small proper motion of S Ori 70 (11.0 ± 5.9 mas yr-1) indicates that this object is farther away than expected if it were a single field T dwarf lying in the foreground of the Orionis cluster. Our measurement is consistent with the proper motion of the cluster within 1.5 the astrometric uncertainty. Conclusions.Taking into account both S Ori 70\u27s proper motion and the new near- and mid-infrared colors, a low-gravity atmosphere remains as the most likely explanation for our observations. This supports S Ori 70\u27s membership in Orionis, with an estimated mass in the interval 2-7 , in agreement with our previous derivation. © 2008 ESO

Multiplicity Of Very Low-Mass Objects In The Upper Scorpius Ob Association: A Possible Wide Binary Population

Aims. Properties of multiplicity, such as the multiplicity frequency, the distribution of mass ratios and periods, provide important informations on the formation processes at work. Studying these properties in different environments and at different ages allows us to constrain the models of formation and to understand the influence of the environment on the star formation. Methods. We report the initial results of a VLT/NACO high spatial resolution imaging survey for multiple systems among 58 M-type members of the nearby Upper Scorpius OB association. Results. Nine pairs with separations below 1 have been resolved. Their small angular separations and the similarity in the brightness of the components (ΔMagK \u3c 1 for all of them), indicate there is a reasonable likelihood that several of them are true binaries rather than chance projections. Follow-up imaging observations with WHT/LIRIS of the two widest binaries confirm that their near-infrared colours are consistent with physical very low-mass binaries. For one of these two binaries, WHT/LIRIS spectra of each component were obtained. We find that the two components have similar M6-M7 spectral types and signatures of low-gravity, as expected for a young brown dwarf binary in this association. Conclusions. Our preliminary results indicate a possible population of very low-mass binaries with semimajor axis in the range 100-150 AU, which has not been seen in the Pleiades open cluster. If these candidates are confirmed (one is confirmed by this work), these results would indicate that the binary properties of very low-mass stars and brown dwarfs may depend on the environment where they form. © ESO 2006

S Ori J053825.4-024241: A Classical T Tauri-Like Object At The Substellar Boundary

We present a spectrophotometric analysis of SOri J053825.4-024241, a candidate member close to the substellar boundary of the young (1-8Myr), nearby (∼360pc) σ Orionis star cluster. Our optical and near-infrared photometry and low-resolution spectroscopy indicate that S Ori J053825.4-024241 is a likely cluster member with a mass estimated from evolutionary models at 0.06 -0.02+0.07 M ⊙, which makes the object a probable brown dwarf. The radial velocity of S Ori J053825.4-024241 is similar to the cluster systemic velocity. This target, which we have classified as an M 6.0 ±1.0 low-gravity object, shows excess emission in the near-infrared and anomalously strong photometric variability for its type (from the blue to the J band), suggesting the presence of a surrounding disc. The optical spectroscopic observations show a continuum excess at short wavelengths and a persistent and resolved H α emission (pseudo-equivalent width of ∼-250 Å) in addition to the presence of other forbidden and permitted emission lines, which we interpret as indicating accretion from the disc and possibly mass loss. We conclude that despite the low mass of S Ori J053825.4-024241, this object exhibits some of the properties typical of active classical T Tauri stars. © ESO 2005

Discovery Of A Wide Planetary-Mass Companion Of A Brown Dwarf In The Upper Scorpius Association

We present the discovery of a 14+2-8 Mjup companion located at 670 AU from UScoC-TIO 108, a 60±20MJup brown dwarf of the very young Upper Scorpius association. Optical and near-infrared photometry and spectroscopy confirm that both the primary and secondary are very cool objects, with Teff of 2700 and 2100 K, respectively, and that they are bona fide young members of the association. We will discuss the implications of the existence of wide substellar companions in current models of formation of these very low-mass objects. The results of this proceeding is also published in Béjar et al. 2008, ApJ, 673, L185. © 2009 American Institute of Physics

Discs Of Planetary-Mass Objects In Σ Orionis

Aims. We searched for infrared flux excesses of planetary-mass candidates in the δ Orionis cluster (∼3 Myr, ∼350 pc). Methods. Using IJHKs data from the literature and the [3.6], [4.5], [5.8], and [8.0] IRAC images of the σ Orionis cluster from the Spitzer Space Telescope public archives, we constructed colour-colour diagrams and spectral energy distributions from 0.8 to 8.0μm of cluster candidates fainter than J = 18.0 mag, i.e. the planetary-mass borderline for σ Orionis. Results. Infrared flux excesses are detected longward of μm in seven objects (S Ori 54,55,56,58,60, S Ori J053956.8-025315 and S Ori J053858.6-025228) with masses estimated in the range 7-14 MJup. Emission at shorter wavelengths (4.5μm) in excess of the photosphere is probably observed in S Ori 56 and S Ori J053858.6-025228. The faintest and least massive object, S Ori 60, exhibits flux excess only at 8 μm. We ascribe these infrared excesses to the presence of circumsubstellar warm discs, providing additional confirmation for the objects\u27 membership of σ Orionis. The observed incidence of inner discs around planetary-mass objects is ≥50%, which is consistent with the measured inner disc frequency among cluster brown dwarfs and low-mass stars, suggesting that these objects share a common origin. However, there is a trend for the inner disc rate to increase with decreasing mass (from 10 M⊖ through the substellar domain), which may be due to a mass-dependent timescale for the dissipation of the interior discs. © ESO 2007