Observing exoplanets from the planet Earth: how our revolution around the Sun affects the detection of 1-year periods

We analysed a selected sample of exoplanets with orbital periods close to 1 year to study the effects of the spectral window on the data, affected by the 1 cycle/year aliasing due to the Earth motion around the Sun. We pointed out a few cases where a further observational effort would largely improve the reliability of the orbital solutions.Comment: Contribution to the Focus Point on "Highlights of Planetary Science in Italy" edited by P. Cerroni, E. Dotto, P. Paolicch

Stellar contributions to the line profiles of high-resolution transmission spectra of exoplanets

In-depth studies of exoplanetary atmospheres are starting to become reality. In order to unveil their properties in detail, we need spectra with a higher S/N and also more sophisticated analysis methods. With high-resolution spectrographs, we can not only detect the sodium feature in the atmosphere of exoplanets, but also characterize it by studying its line profile. After finding a clearly w-shaped sodium line profile in the transmission spectrum of HD189733b, we investigated possible sources of contamination given by the star and tried to correct for these spurious deformations. By analyzing the single transmission spectra of HD189733b in the wavelength space, we show that the main sodium signal that causes the absorption in the transmission spectrum is centered on the stellar rest frame. We concentrate on two main stellar effects that contaminate the transmission spectrum: center-to-limb variations and stellar rotation. We show the effects on the line profile: while we correct for the CLV using simulated theoretical stellar spectra, we provide a new method, based directly on observational data, to correct for the RM contribution to the line profile of the retrieved transmission spectrum. We apply the corrections to the spectra of HD189733b. Our analysis shows line profiles of the Na D lines in the transmission spectrum that are narrower than reported previously. The correction of the D2 line, which is deeper than the D1, is probably still incomplete since the planetary radius is larger at this wavelength. A careful detrending from spurious stellar effects followed by an inspection in the velocity space is mandatory when studying the line profile of atmospheric features in the high-resolution transmission spectrum of exoplanets. Data with higher S/N coupled with improved atmospheric models will allow us to adapt the magnitude of the corrections of stellar effects in an iterative way.Comment: 8 pages, 11 figures. Accepted for publication in A&A, language edited versio

Stellar masks and bisector's shape for M-type stars observed in the GAPS Programme with HARPS-N at TNG

The HARPS/HARPS-N Data Reduction Software (DRS) relies on the cross-correlation between the observed spectra and a suitable stellar mask to compute a cross-correlation function (CCF) to be used both for the radial velocity (RV) computation and as an indicator of stellar lines asymmetry, induced for example by the stellar activity. Unfortunately the M2 mask currently used by the HARPS/HARPS-N DRS for M-type stars results in heavily distorted CCFs. We created several new stellar masks in order to decrease the errors in the RVs and to improve the reliability of the activity indicators as the bisector's span. We obtained very good results with a stellar mask created from the theoretical line list provided by the VALD3 database for an early M-type star (T$_{\mathrm{eff}}$=3500~K and $\log{g}=4.5$). The CCF's shape and relative activity indicators improved and the RV time-series allowed us to recover known exoplanets with periods and amplitudes compatible with the results obtained with HARPS-TERRA.Comment: 13 pages, 8 figures Accepted for publication in Experimental Astronom

The ultraviolet habitable zone of exoplanets

The dozens of rocky exoplanets discovered in the Circumstellar Habitable Zone (CHZ) currently represent the most suitable places to host life as we know it outside the Solar System. However, the presumed presence of liquid water on the CHZ planets does not guarantee suitable environments for the emergence of life. According to experimental studies, the building blocks of life are most likely produced photochemically in presence of a minimum ultraviolet (UV) flux. On the other hand, high UV flux can be life-threatening, leading to atmospheric erosion and damaging biomolecules essential to life. These arguments raise questions about the actual habitability of CHZ planets around stars other than Solar-type ones, with different UV to bolometric luminosity ratios. By combining the "principle of mediocricy" and recent experimental studies, we define UV boundary conditions (UV-habitable Zone, UHZ) within which life can possibly emerge and evolve. We investigate whether exoplanets discovered in CHZs do indeed experience such conditions. By analysing Swift-UV/Optical Telescope data, we measure the near ultraviolet (NUV) luminosities of 17 stars harbouring 23 planets in their CHZ. We derive an empirical relation between NUV luminosity and stellar effective temperature. We find that eighteen of the CHZ exoplanets actually orbit outside the UHZ, i.e., the NUV luminosity of their M-dwarf hosts is decisively too low to trigger abiogenesis - through cyanosulfidic chemistry - on them. Only stars with effective temperature >3900 K illuminate their CHZ planets with enough NUV radiation to trigger abiogenesis. Alternatively, colder stars would require a high-energy flaring activity.Comment: 8 pages, 3 figure

GAPS: Using the information of the HARPS-N exposure-meter to improve the precision of RV measurements

While taking a spectrum, if the flux received from the detector is not equally time-distributed while the shutter is open, the Radial Velocity (RV) information we receive can’t be exactly referred to the middle of the exposure. That’s why last generation spectrographs use the information of an exposure-meter to measure the centroid of the flux received vs. time, to correct the time information in case of a change in the seeing conditions during the exposure. The HARPS-N reduction pipeline does not take into account, up to now, the exposure-meter information, using by default the mid-exposure time as the reference value for each exposure. If the information of the exposure-meter centroid in the fits files of HARPS-N (keyword ‘HIERARC EXP_METER_A EXP CENTROID’) is reliable and trustworthy, it’s not difficult to include it in the analysis of the radial velocities (even if it’s not always present). The problem is to correct for the Barycentric Earth Radial Velocity (BERV) at the relative time, in a homogeneous way to the HARPS-N pipeline. With the correction of the BERV at the right time, we can insert the information of the exposure- meter centroid in the RVs estimation of the pipeline, where available

SIOUX project: a simultaneous multiband camera for exoplanet atmospheres studies

The exoplanet revolution is well underway. The last decade has seen order-of-magnitude increases in the number of known planets beyond the Solar system. Detailed characterization of exoplanetary atmospheres provide the best means for distinguishing the makeup of their outer layers, and the only hope for understanding the interplay between initial composition chemistry, temperature-pressure atmospheric profiles, dynamics and circulation. While pioneering work on the observational side has produced the first important detections of atmospheric molecules for the class of transiting exoplanets, important limitations are still present due to the lack of sys- tematic, repeated measurements with optimized instrumentation at both visible (VIS) and near-infrared (NIR) wavelengths. It is thus of fundamental importance to explore quantitatively possible avenues for improvements. In this paper we report initial results of a feasibility study for the prototype of a versatile multi-band imaging system for very high-precision differential photometry that exploits the choice of specifically selected narrow-band filters and novel ideas for the execution of simultaneous VIS and NIR measurements. Starting from the fundamental system requirements driven by the science case at hand, we describe a set of three opto-mechanical solutions for the instrument prototype: 1) a radial distribution of the optical flux using dichroic filters for the wavelength separation and narrow-band filters or liquid crystal filters for the observations; 2) a tree distribution of the optical flux (implying 2 separate foci), with the same technique used for the beam separation and filtering; 3) an exotic solution consisting of the study of a complete optical system (i.e. a brand new telescope) that exploits the chromatic errors of a reflecting surface for directing the different wavelengths at different foci

Report on the fourth run of the ESO LP 185.D-0056 ([email protected])

The ESO Large Programme 185.D-0056 ([email protected]) continued with the fourth run. The log of the observations performed in December 2011 and January 2012, a tip on the preparation of the Observing Blocks, the data backup, and the situation of the publications are given

New route for Tizanidine administration: a pharmacokinetics and light microscope autoradiography study

Spasticity could represent a complication of several central nervous system (CNS) disorders. Multiple sclerosis and painful paroxysmal syndromes (e.g. trigeminal neuralgia) are pathologies in which anti-spastic drugs are used to a greater extent . Baclofen, tizanidine (TIZ), benzodiazepines, dantrolene, and, more recently, gabapentin are the pharmacological agents more widely used. Baclofen, TIZ, benzodiazepines, gabapentin, clonidine but not dantrolene are active on CNS. The  alpha2 adrenoceptor agonist TIZ is one of the most effective and largely used  anti-spastic drugs. Oral treatment is the only route of anti-spastics administration, although it may cause problems of bioavailability and/or compliance in spastic patients with impaired deglutition. This study was designed to assess the possibility of develop a new  route of administration of TIZ and to identify its targets in the spinal cord. New Zealand rabbits were treated with oral (OR , n=6), intramuscular (IM, n=6) or  intranasal (IN, n=6) TIZ (3.2 mg/kg/day). Plasma concentration was measured by HPLC on samples collected at 0, 30, 60, 90, 120 and 480 min after treatment. Curves of average concentrations of TIZ vs. time were constructed. In plasma, TIZ reached a peak between 45-65 min after administration. Cmax was in the range of 268.33–1213.64 ng/ml for IM treatment, of 73.95–135.92 ng/ml for IN treatment and of 16.86–857.25 ng/ml for OR treatment. After pharmacokinetic studies, different spinal cord tracts were removed and used for radioligand binding assay and autoradiography. Using [3H]-RX821002 ([3H]-RX) (0.1-14nM), the Kd and Bmax for every spinal cord segment were calculated. The non-specific binding was obtained with 100µM of (-)-epinephrine. [3H]-RX sites were accumulated in the superficial laminae of dorsal horn. Dense [3H]-RX binding in control was seen over the superficial dorsal horn (laminae I-II) and centrally located lamina X. The ventral horn showed moderate levels of binding. [3H]-RX was displaced after TIZ treatment using different administration routes. The heaviest accumulation of silver grains (lowest displacement of TIZ) occurred after OR administration of the compound, the lowest after IM administration. These results suggest that both IM and IN administration of TIZ may represent routes of administration of the drug alternative to the OR one.Considering predictable adverse effects of IM treatment, the IN administration could represent the elective route to administrate this kind of drugs

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3NIT(C6H4OPh)]: A μ+ spin relaxation study

The spin dynamics of the molecular magnetic chain [Dy(hfac)3NIT(C6H4OPh)] were investigated by means of the Muon Spin Relaxation (\u3bc+SR) technique. This system consists of a magnetic lattice of alternating Dy(III) ions and radical spins, and exhibits single-chain-magnet behavior. The magnetic properties of [Dy(hfac)3NIT(C6H4OPh)] have been studied by measuring the magnetization vs. temperature at different applied magnetic fields (H = 5, 3500, and 16500 Oe) and by performing \u3bc+SR experiments vs. temperature in zero field and in a longitudinal applied magnetic field H = 3500 Oe. The muon asymmetry P(t) was fitted by the sum of three components, two stretched-exponential decays with fast and intermediate relaxation times, and a third slow exponential decay. The temperature dependence of the spin dynamics has been determined by analyzing the muon longitudinal relaxation rate \u3bbinterm(T), associated with the intermediate relaxing component. The experimental \u3bbinterm(T) data were fitted with a corrected phenomenological Bloembergen-Purcell-Pound law by using a distribution of thermally activated correlation times, which average to \u3c4 = \u3c40 exp(\u394/kBT), corresponding to a distribution of energy barriers \u394. The correlation times can be associated with the spin freezing that occurs when the system condenses in the ground state