The Posttransit Tail of WASP-107b Observed at 10830 Å

Understanding the effects of high-energy radiation and stellar winds on planetary atmospheres is vital for explaining the observed properties of close-in exoplanets. Observations of transiting exoplanets in the triplet of metastable helium lines at 10830 Å allow extended atmospheres and escape processes to be studied for individual planets. We observed one transit of WASP-107b with NIRSPEC on Keck at 10830 Å. Our observations, for the first time, had significant posttransit phase coverage, and we detected excess absorption for over an hour after fourth contact. The data can be explained by a comet-like tail extending out to ∼7 planet radii, which corresponds to roughly twice the Roche lobe radius of the planet. Planetary tails are expected based on three-dimensional simulations of escaping exoplanet atmospheres, particularly those including the interaction between the escaped material and strong stellar winds, and have been previously observed at 10830 Å in at least one other exoplanet. With both the largest midtransit absorption signal and the most extended tail observed at 10830 Å, WASP-107b remains a keystone exoplanet for atmospheric escape studies.

A cosmologically consistent millicharged dark matter solution to the EDGES anomaly of possible string theory origin

Analysis of EDGES data shows an absorption signal of the redshifted 21-cm line of atomic hydrogen at z ∼ 17 which is stronger than expected from the standard ΛCDM model. The absorption signal interpreted as brightness temperature T21 of the 21-cm line gives an amplitude of $$ -{500}_{-500}^{+200} $$ − 500 − 500 + 200 mK at 99% C.L. which is a 3.8σ deviation from what the standard ΛCDM cosmology gives. We present a particle physics model for the baryon cooling where a fraction of the dark matter resides in the hidden sector with a U(1) gauge symmetry and a Stueckelberg mechanism operates mixing the visible and the hidden sectors with the hidden sector consisting of dark Dirac fermions and dark photons. The Stueckelberg mass mixing mechanism automatically generates a millicharge for the hidden sector dark fermions providing a theoretical basis for using millicharged dark matter to produce the desired cooling of baryons seen by EDGES by scattering from millicharged dark matter. We compute the relic density of the millicharged dark matter by solving a set of coupled equations for the dark fermion and dark photon yields and for the temperature ratio of the hidden sector and the visible sector heat baths. For the analysis of baryon cooling, we analyze the evolution equations for the temperatures of baryons and millicharged dark matter as a function of the redshift. We exhibit regions of the parameter space which allow consistency with the EDGES data. We note that the Stueckelberg mechanism arises naturally in strings and the existence of a millicharge would point to its string origin.

Maximum Absorption of the Global 21 cm Spectrum in the Standard Cosmological Model

The absorption feature in the global spectrum is likely the first 21 cm observable from the cosmic dawn, which provides valuable insights into the earliest history of structure formation. We run a set of high-resolution hydrodynamic simulations of early structure formation to assess the effect of nonlinear structure formation on the maximum absorption level (i.e., assuming the spin temperature coupling is saturated) of the global 21 cm spectrum in the standard cosmological framework. We ignore the star formation and feedbacks, which also tend to reduce the absorption signal, but take into account the inevitable nonlinear density fluctuations in the intergalactic medium (IGM), shock-heating, and Compton-heating, which can reduce the absorption level. We found that the combination of these reduced the maximum absorption signal by ∼15% at redshift 17, as compared with the homogeneous or linearly-fluctuating IGM. These effects have to be carefully accounted for when interpreting the observational results, especially when considering the necessity of introducing new physics.

Chemical detection of certain greenhouse gases by the LIDAR Technique

The aim of this study is to detect the chemical elements of the greenhouse effect from the LIDAR signal. Using a digital program developed by Fortran language, and based on spectral data. In the present work, The LIDAR sample is clearly contains water vapor and carbon dioxide. According to our results, the content of the sample with methane and the non-detection of nitrogen oxide, due to the absence of its absorption signal in the spectral range of the experimental signal. Carbon dioxide is one of the most dangerous greenhouse gases, our results show that 1 mole of this gas requires 1.45 moles of water vapor.

Spectroscopy Study of Honey Pineapple Peels Extracted in Different Solvents

In the present work, we investigated the extract of honey pineapple peels in distilled water, ethanol, and acetone solvents. The spectroscopy study of each extract was performed using a Fourier transform infrared (FTIR) spectrometer, an ultraviolet-visible (UV-Vis) spectrophotometer, and a spectrofluorometer. The FTIR spectrum of the distilled water extract indicated that the distilled water extract may contain alcohol or carboxylic acid compounds. Meanwhile, the ethanolic extract may contain alcohol or carboxylic acid, or ether compounds. On the other hand, the acetone extract may contain alcohol or ether or aromatic or aliphatic compounds. The UV-Vis spectrum of the honey pineapple peels extracted in the distilled water, ethanol, and acetone showed a broad absorption signal at UV region (< 300 nm), four absorption signals at UV region (232-368 nm), and four absorption signals at UV region (231-368 nm) with a weak absorption signal at the visible region at 559 nm, respectively. The distilled water and acetone extracts gave fluorescence signals, however, the ethanolic extract showed no fluorescence intensity. From the FTIR, UV-Vis, and fluorescence spectra characterization, the extracted natural pigments from the honey pineapple peels in distilled water, ethanol, and acetone solvents were identified. The distilled water extract may contain polar flavonoid or steroid compounds while the ethanolic extract may contain polar carotenoid pigments. On the other hand, the acetone extract may contain carotenoid and chlorophyll pigments as shown by an emission signal at 670 nm.

Expanding the range of determination of elements on the Grand-AAS atomic absorption spectrometer using several of their absorption lines

One limitation of atomic absorption spectrometry is the narrow range of measurable concentration (1–2 orders of magnitude). In simultaneous multi-element analysis, this may require multiple dilutions of the sample to determine several elements with different concentrations in the sample. Possible ways to expand the range are to linearize the calibration curve by correcting the integral of the absorption signal or to use absorption values on the line wing as an analytical signal and plot several graphs along one line at different distances from its center. Both methods have their drawbacks. We propose another method for expanding the measurable concentration range by using less sensitive absorption lines of elements. A number of elements are identified that have a sufficient number of lines with different sensitivities. The proposed method is compared with the method of linearization of the calibration graph and the calculation of the absorption signal on the line wing. Using as an example Co and Ni, which have sufficiently rich absorption spectra, we have shown the possibility of expanding the measurable concentration range by using several absorption lines: for cobalt, the range is expanded to six orders of magnitude, and for nickel, to five orders of magnitude. Calibration curves are plotted in the concentration ranges 0.24–250.000 μg/L for cobalt and 1.9–250.000 μg/L for nickel. The calibration error is lower than that of the linearization method: 5% against 25 % for cobalt and 4% against 24% for nickel. Thus, the proposed method can be used for simultaneous multielement determination in a wide range of concentrations without diluting the sample.

Can EDGES observation favour any dark matter model?

ABSTRACT The recent detection of the 21-cm absorption signal by the EDGES collaboration has been widely used to constrain the basic properties of dark matter particles. However, extracting the parameters of the 21-cm absorption signal relies on a chosen parametrization of the foreground radio emission. Recently, the new parametrizations of the foreground and systematics have been proposed, showing significant deviations of the 21-cm signal parameters from those assumed by the original EDGES paper. In this paper, we consider this new uncertainty, comparing the observed signal with the predictions of several dark matter models, including the widely used cold dark matter model, 1–3 keV warm dark matter models, and 7 keV sterile neutrino (SN7) model, capable of producing the reported 3.5 keV line. We show that all these dark matter models cannot be statistically distinguished using the available EDGES data.

The GAPS programme at TNG

Context. Exoplanets orbiting very close to their parent star are strongly irradiated. This can lead the upper atmospheric layers to expand and evaporate into space. The metastable helium (He I) triplet at 1083.3 nm has recently been shown to be a powerful diagnostic to probe extended and escaping exoplanetary atmospheres. Aims. We perform high-resolution transmission spectroscopy of the transiting hot Jupiter HD 189733 b with the GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo, taking advantage of the simultaneous optical+near infrared spectral coverage to detect He I in the planet’s extended atmosphere and to gauge the impact of stellar magnetic activity on the planetary absorption signal. Methods. Observations were performed during five transit events of HD 189733 b. By comparison of the in-transit and out-of-transit GIANO-B observations, we computed high-resolution transmission spectra. We then used them to perform equivalent width measurements and carry out light-curves analyses in order to consistently gauge the excess in-transit absorption in correspondence with the He I triplet. Results. We spectrally resolve the He I triplet and detect an absorption signal during all five transits. The mean in-transit absorption depth amounts to 0.75 ± 0.03% (25σ) in the core of the strongest helium triplet component. We detect night-to-night variations in the He I absorption signal likely due to the transit events occurring in the presence of stellar surface inhomogeneities. We evaluate the impact of stellar-activity pseudo-signals on the true planetary absorption using a comparative analysis of the He I 1083.3 nm (in the near-infrared) and the Hα (in the visible) lines. Using a 3D atmospheric code, we interpret the time series of the He I absorption lines in the three nights not affected by stellar contamination, which exhibit a mean in-transit absorption depth of 0.77 ± 0.04% (19σ) in full agreement with the one derived from the full dataset. In agreement with previous results, our simulations suggest that the helium layers only fill part of the Roche lobe. Observations can be explained with a thermosphere heated to ~12 000 K, expanding up to ~1.2 planetary radii, and losing ~1 g s−1 of metastable helium. Conclusions. Our results reinforce the importance of simultaneous optical plus near infrared monitoring when performing high-resolution transmission spectroscopy of the extended and escaping atmospheres of hot planets in the presence of stellar activity.