Corrigendum to "The upper atmosphere of the exoplanet HD209458b revealed by the sodium D lines: Temperature-pressure profile, ionization layer and thermosphere" [2011, A&A, 527, A110]

An error was detected in the code used for the analysis of the HD209458b sodium profile (Vidal-Madjar et al. 2011). Here we present an updated T-P profile and briefly discuss the consequences.Comment: Published in Astronomy & Astrophysics, 533, C

A new powerful method for probing the atmospheres of transiting exoplanets

Although atmospheric transmission spectroscopy of HD209458b with the Hubble Space Telescope has been very successful, attempts to detect its atmospheric absorption features using ground-based telescopes have so far been fruitless. Here we present a new method for probing the atmospheres of transiting exoplanets which may be more suitable for ground-based observations, making use of the Rossiter effect. During a transit, an exoplanet sequentially blocks off light from the approaching and receding parts of the rotating star, causing an artificial radial velocity wobble. The amplitude of this signal is directly proportional to the effective size of the transiting object, and the wavelength dependence of this effect can reveal atmospheric absorption features, in a similar way as with transmission spectroscopy. The advantage of this method over conventional atmospheric transmission spectroscopy is that it does not rely on accurate photometric comparisons of observations on and off transit, but instead depends on the relative velocity shifts of individual stellar absorption lines within the same on-transit spectra. We used an archival VLT/UVES data set to apply this method to HD209458. The amplitude of the Rossiter effect is shown to be 1.7+-1.2 m/sec higher in the Sodium D lines than in the weighted average of all other absorption lines in the observed wavelength range, corresponding to an increment of 4.3+-3% (1.4 sigma). The uncertainty in this measurement compares to a photometric accuracy of 5e-4 for conventional atmospheric transmission spectroscopy, more than an order of magnitude higher than previous attempts using ground-based telescopes. Observations specifically designed for this method could increase the accuracy further by a factor 2-3.Comment: LaTex, 5 pages, 4 figs; submitted to MNRAS Letter

AGROCHEMICAL STUDY IN THE AREA OF SILIȘTEA-GUMEȘTI TELEORMAN COUNTY, WITH AN AREA OF 210 HA, WITH THE PURPOSE OF ELABORATING THE FERTILIZATION PLAN ON CROPS

In order to carry out this study, work was carried out on the morphological, physical and chemical characterization, determining the productive potential of the soil cover, enunciating the measures of soil improvement and elaborating the fertilization plan on crops. The field stage includes the presentation of general and local ecopedological conditions. In this regard, observations were made on the territory from the point of view of each ecopedological factor. Based on the movement on the ground, observations were made on the micro-relief, the level of the groundwater, the vegetation and the degree of anthropization of the soil cover following the mobilization, preparation of the germination bed and current maintenance. The soil samples were collected according to the cadastral plan, with an area of 210 ha being located on the radius of SilișteaGumești commune, Teleorman county. For the characterization of the soil cover from the above mentioned surface, a soil profile and a few surveys were carried out, in order to correctly identify the representative soil type. Also, agrochemical mapping was performed, 44 soil samples were collected from the arable horizon (0-20 cm) in disturbed system (in plastic bags). The description of the pedogenetic conditions and the soil cover from soil boiling, was carried out according to the "Guide for the description in the field of the soil profile and the specific environmental conditions", authors: Munteanu I., Florea N., 2009 and "Methodology for the Development of Pedological Studies ", ICPA, 1987. The classification of soils at type and subtype level was made according to" Romanian Soil Taxonomy System (SRTS) ", ICPA, 2012

Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b

[Context] The first detection of an atmosphere around an extrasolar planet was presented by Charbonneau and collaborators in 2002. In the optical transmission spectrum of the transiting exoplanet HD209458b, an absorption signal from sodium was measured at a level of 0.023+-0.006%, using the STIS spectrograph on the Hubble Space Telescope. Despite several attempts, so far only upper limits to the Na D absorption have been obtained using telescopes from the ground, and the HST result has yet to be confirmed. [Aims] The aims of this paper are to re-analyse data taken with the High Dispersion Spectrograph on the Subaru telescope, to correct for systematic effects dominating the data quality, and to improve on previous results presented in the literature. [Methods] The data reduction process was altered in several places, most importantly allowing for small shifts in the wavelength solution. The relative depth of all lines in the spectra, including the two sodium D lines, are found to correlate strongly with the continuum count level in the spectra. These variations are attributed to non-linearity effects in the CCDs. After removal of this empirical relation the uncertainties in the line depths are only a fraction above that expected from photon statistics. [Results] The sodium absorption due to the planet's atmosphere is detected at >5 sigma, at a level of 0.056+-0.007% (2x3.0 Ang band), 0.070+-0.011% (2x1.5 Ang band), and 0.135+-0.017% (2x0.75 Ang band). There is no evidence that the planetary absorption signal is shifted with respect to the stellar absorption, as recently claimed for HD189733b. The measurements in the two most narrow bands indicate that some signal is being resolved.[abridged]Comment: Latex, 7 pages: accepted for publication in Astronomy & Astrophysic

Hot-Jupiters and hot-Neptunes: a common origin?

We compare evolutionary models for close-in exoplanets coupling irradiation and evaporation due respectively to the thermal and high energy flux of the parent star with observations of recently discovered new transiting planets. The models provide an overall good agreement with observations, although at the very limit of the quoted error bars of OGLE-TR-10, depending on its age. Using the same general theory, we show that the three recently detected hot-Neptune planets (GJ436, $\rho$ Cancri, $\mu$ Ara) may originate from more massive gas giants which have undergone significant evaporation. We thus suggest that hot-Neptunes and hot-Jupiters may share the same origin and evolution history. Our scenario provides testable predictions in terms of the mass-radius relationships of these hot-Neptunes.Comment: 5 pages, 2 figures, accepted in A&A Lette

Gas Absorption Detected from the Edge-on Debris Disk Surrounding HD32297

Near-infrared and optical imaging of HD32297 indicate that it has an edge-on debris disk, similar to beta Pic. I present high resolution optical spectra of the NaI doublet toward HD32297 and stars in close angular proximity. A circumstellar absorption component is clearly observed toward HD32297 at the stellar radial velocity, which is not observed toward any of its neighbors, including the nearest only 0.9 arcmin away. An interstellar component is detected in all stars >90 pc, including HD32297, likely due to the interstellar material at the boundary of the Local Bubble. Radial velocity measurements of the nearest neighbors, BD+07 777s and BD+07 778, indicate that they are unlikely to be physically associated with HD32297. The measured circumstellar column density around HD32997, log N(NaI) ~ 11.4, is the strongest NaI absorption measured toward any nearby main sequence debris disk, even the prototypical edge-on debris disk, beta Pic. Assuming that the morphology and abundances of the gas component around HD32297 are similar to beta Pic, I estimate an upper limit to the gas mass in the circumstellar disk surrounding HD32297 of ~0.3 M_Earth.Comment: 13 pages, 2 figures; Accepted for publication in ApJ Letter

The D/H Ratio in Interstellar Gas Towards G191-B2B

We reinvestigate the question of spatial variation of the local D/H abundance, using both archival GHRS spectra, and new echelle spectra of G191-B2B obtained with the Space Telescope Imaging Spectrograph (STIS) aboard HST. Our analysis uses stratified line-blanketed non-LTE model atmosphere calculations to determine the shape of the intrinsic WD Lyman-alpha profile and estimate the WD photospheric contamination of the interstellar lines. Although three velocity components were reported previously towards G191-B2B, we detect only two velocity components. The first component is at V(hel) ~ 8.6 km/s and the second at V(hel) ~ 19.3 km/s, which we identify with the Local Interstellar Cloud (LIC). From the STIS data we derive D/H = 1.60(+0.39,-0.27)X10^-5 for the LIC component, and D/H > 1.26X10^-5 for the 8.6 km/s component (uncertainties denote 2-sigma or 95% confidence limits). The STIS data provide no evidence for local or component-to-component variation in the D/H ratio. Despite using two velocity components for the profile fitting and using a more physically realistic WD Lyman-alpha profile for G191-B2B, our re-analysis of the GHRS data indicates a component-to-component variation as well as a variation of the D/H ratio in the LISM, neither of which are supported by the newer STIS data. We believe the most probable cause for this difference is the characterization of the background due to scattered light in the GHRS and STIS spectrographs. The two-dimensional MAMA detectors of STIS measure both the spatial and wavelength dependences of scattered light, allowing more accurate scattered light corrections than was possible with GHRS.Comment: Accepted for publication in Astrophysical Journal Letters. 10 pages + 3 figures. (Abstract is abridged.

Formation and structure of the three Neptune-mass planets system around HD69830

Since the discovery of the first giant planet outside the solar system in 1995 (Mayor & Queloz 1995), more than 180 extrasolar planets have been discovered. With improving detection capabilities, a new class of planets with masses 5-20 times larger than the Earth, at close distance from their parent star is rapidly emerging. Recently, the first system of three Neptune-mass planets has been discovered around the solar type star HD69830 (Lovis et al. 2006). Here, we present and discuss a possible formation scenario for this planetary system based on a consistent coupling between the extended core accretion model and evolutionary models (Alibert et al. 2005a, Baraffe et al. 2004,2006). We show that the innermost planet formed from an embryo having started inside the iceline is composed essentially of a rocky core surrounded by a tiny gaseous envelope. The two outermost planets started their formation beyond the iceline and, as a consequence, accrete a substantial amount of water ice during their formation. We calculate the present day thermodynamical conditions inside these two latter planets and show that they are made of a rocky core surrounded by a shell of fluid water and a gaseous envelope.Comment: Accepted in AA Letter

Detection of nitrogen gas in the β pictoris circumstellar disk

Context. The gas composition of the debris disc surrounding β Pictoris is rich in carbon and oxygen relative to solar abundances. Two possible scenarios have been proposed to explain this enrichment. The preferential production scenario suggests that the produced gas may be naturally rich in carbon and oxygen, while the alternative preferential depletion scenario states that the enrichment has evolved to the current state from a gas with solar-like abundances. In the latter case, the radiation pressure from the star expels the gas outwards, leaving behind species that are less sensitive to stellar radiation such as C and O. Nitrogen is not sensitive to radiation pressure either as a result of its low oscillator strength, which would make it also overabundant under the preferential depletion scenario. The abundance of nitrogen in the disc may therefore provide clues to why C and O are overabundant. Aims. We aim to measure the nitrogen column density in the direction of β Pictoris (including contributions by the interstellar medium and circumstellar disc), and use this information to distinguish these different scenarios to explain the C and O overabundance. Methods. Using far-UV spectroscopic data collected by the Hubble Space Telescope’s Cosmic Origins Spectrograph (COS) instrument, we analysed the spectrum and characterised the NI triplet by modelling the absorption lines. Results. We measure the nitrogen column density in the direction of β Pictoris for the first time, and find it to be log(NNI/1 cm2) = 14.9 ± 0.7. The nitrogen gas is found to be consistent with solar abundances and Halley dust. We also measure an upper limit for the column density of MnII in the disc at log(NMnII/1 cm2)CS = 12.7+0.1 and calculate the column density of SIII** in the disc to be log(NSIII★★/1 cm2)CSX = 14.2 ± 0.1. Both results are in good agreement with previous studies. Conclusions. The solar nitrogen abundance supports the preferential production hypothesis, in which the composition of gas in β Pictoris is the result of photodesorption from icy grains that are rich in C and O or collisional vaporisation of C- and O-rich dust in the disc. It does not support the hypothesis that C and O are overabundant because C and O are insensitive to radiation pressure, which would cause them to accumulate in the disc

Quasi-molecular lines in Lyman wings of cool DA white dwarfs; Application to FUSE observations of G231-40

We present new theoretical calculations of the total line profiles of Lyman alpha and Lyman beta which include perturbations by both neutral hydrogen AND protons and all possible quasi-molecular states of H_2 and H_2^+. They are used to improve theoretical modeling of synthetic spectra for cool DA white dwarfs. We compare them with FUSE observation of G231-40. The appearance of the line wings between Lyman alpha and Lyman beta is shown to be sensitive to the relative abundance of hydrogen ions and neutral atoms, and thereby to provide a temperature diagnostic for stellar atmospheres and laboratory plasmas.Comment: 6 pages, 4 figures, accepted for publication in Astronomy and Astrophysic