We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting the nearby M3.5 V dwarf star, GJ 3929 (G 180-18, TOI-2013). Joint modelling of photometric observations from TESS sectors 24 ...and 25 together with 73 spectroscopic observations from CARMENES and follow-up transit observations from SAINT-EX, LCOGT, and OSN yields a planet radius of
R
b
= 1.150 ± 0.040
R
⊕
, a mass of
M
b
= 1.21 ± 0.42
M
⊕
, and an orbital period of
P
b
= 2.6162745 ± 0.0000030
d
. The resulting density of
ρ
b
= 4.4 ± 1.6 g cm
−3
is compatible with the Earth’s mean density of about 5.5 g cm
−3
. Due to the apparent brightness of the host star (
J
= 8.7 mag) and its small size, GJ 3929 b is a promising target for atmospheric characterisation with the JWST. Additionally, the radial velocity data show evidence for another planet candidate with
P
c
= 14.303 ± 0.035 d, which is likely unrelated to the stellar rotation period,
P
rot
= 122 ± 13 d, which we determined from archival HATNet and ASAS-SN photometry combined with newly obtained TJO data.
This paper reports on a simple and efficient process to obtain semiconductor zinc oxide (ZnO) nanoparticles (NPs) using
Artemisia ludoviciana
extract as a chelating agent. The properties of the ZnO ...NPs were analyzed using various characterization techniques, revealing hexagonal and quasi-spherical NPs with sizes going from 30.46 to 16.74 nm and band gap values of 2.5 to 2.2 eV. Additionally, the structural analysis shows a wurtzite phase with no secondary phases, while elemental analysis revealed both the presence of residual carbon from
Artemisia ludoviciana
and the presence of oxygen vacancies. The photocatalytic assay of the obtained ZnO showed excellent methyl orange (MO) degradation. The best performance was observed with E4, which removed 95.8% of MO after being exposed to UV light for 120 min. The results demonstrate that the ZnO NPs obtained using
Artemisia ludoviciana
have good photocatalytic capabilities and show potential to be used in other similar applications.
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•Green synthesis of Zinc Oxide nanoparticles with scale and crystal form.•High purity hexagonal Wurtzite crystal structure.•Decrease in the band gap value dependent on extract ...amount.•EIS testing shows conductivity increments at higher frequency values.
ZnO Nanoparticles (NPs) were synthesized, using different percentages of Mentha spicata extract, and were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and UV–Vis. In order to be used in optoelectronic applications, the nanoparticles were subjected to a pellet manufacturing process to evaluate their electrochemical properties by means of electrochemical impedance spectroscopy (EIS). The synthesized ZnO NPs were approximately 20–70 nm in size, had a Wurtzite tetragonal phase and a band gap of 3.43 to 3.71 eV. The electrochemical properties increased as a function of the extract concentration.
The present work analyzes the electrochemical properties of ZnO nanoparticles synthesized with the help of
Verbascum thapsus
as a reducing agent with different aggregation percentages. The ...synthesized nanoparticles had Band gap values of 2.71, 2.66, and 2.58 eV for the ZnO-1%, ZnO-2%, and ZnO-4% samples, respectively, which is related to their average crystal sizes of 24, 22, and 20 nm. It was also observed that the different samples maintain a Wurtzite-type phase, with a quasi-spherical nanoparticle morphology (sizes between 66.3 and 36.5 nm approximately) and composition of only Zn and O elements. Furthermore, the ATR-IR study showed the vibration peak of Zn–O and a zone that corresponds to the organic molecules of the extract used in biosynthesis. From the electrochemical analysis, it was found that the sample labeled as ZnO-4% has a significantly smaller impedance value than the other two samples. The tests show that the variation in the extract modified the reactance and resistivity of the materials that can be associated to the individual values of the capacitances and resistances expressed in the electrical model of equivalent impedance.
This work present the result of a study on the effects of different amounts of
Daucus carota
(carrot) extract in the green synthesis of zinc oxide (ZnO), and its application as a photocatalyst. Zinc ...nitrate was used as the zinc source while the
Daucus carota
(carrot) extract was used as a reductant and a stabilizing agent in different amounts; 10, 30, 60 and 80 mL. The morphology of the material showed that varying the amount of extract during synthesis made variations in particle size and shape distribution. The band gap values were of 3.13, 3.14, 3.15 and 3.16 eV for the 10, 30, 60 and 80 mL samples, respectively. The photocatalytic properties of the ZnO were evaluated through methylene blue degradation where the sample made with 80 mL presented 95% dye degradation in 120 min, which is more efficient than comparable commercial ZnO nanoparticles.
We report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time ...series in three sectors of the TESS mission. We confirm the planetary nature of both of them using precise radial velocity measurements from the CARMENES and MAROON-X spectrographs, and supplement them with ground-based transit photometry. A joint analysis of all these data reveals that the shorter-period planet, TOI-1468 b (
P
b
= 1.88 d), has a planetary mass of
M
b
= 3.21 ± 0.24
M
⊕
and a radius of
R
b
= 1.280
−0.039
+0.038
R
⊕
, resulting in a density of
ρ
b
= 8.39
−0.92
+1.05
g cm
−3
, which is consistent with a mostly rocky composition. For the outer planet, TOI-1468 c (
P
c
= 15.53 d), we derive a mass of
M
c
= 6.64
−0.68
+0.67
M
⊕
,aradius of
R
c
= 2.06 ± 0.04
R
⊕
,
and a bulk density of
ρ
c
=
2.00
−0.19
+0.21
g cm
−3
, which corresponds to a rocky core composition with a H/He gas envelope. These planets are located on opposite sides of the radius valley, making our system an interesting discovery as there are only a handful of other systems with the same properties. This discovery can further help determine a more precise location of the radius valley for small planets around M dwarfs and, therefore, shed more light on planet formation and evolution scenarios.
Context. The Gl 486 system consists of a very nearby, relatively bright, weakly active M3.5V star at just 8 pc with a warm transiting rocky planet of about 1.3 R⨁ and 3.0 M⨁. It is ideal for both ...transmission and emission spectroscopy and for testing interior models of telluric planets.
Aims. To prepare for future studies, we aim to thoroughly characterise the planetary system with new accurate and precise data collected with state-of-the-art photometers from space and spectrometers and interferometers from the ground.
Methods. We collected light curves of seven new transits observed with the CHEOPS space mission and new radial velocities obtained with MAROON-X at the 8.1m Gemini North telescope and CARMENES at the 3.5m Calar Alto telescope, together with previously published spectroscopic and photometric data from the two spectrographs and TESS. We also performed near-infrared interferometric observations with the CHARA Array and new photometric monitoring with a suite of smaller telescopes (AstroLAB, LCOGT, OSN, TJO). This extraordinary and rich data set was the input for our comprehensive analysis.
Results. From interferometry, we measure a limb-darkened disc angular size of the star Gl 486 at θLDD = 0.390 ± 0.018 mas. Together with a corrected Gaia EDR3 parallax, we obtain a stellar radius R* = 0.339 ± 0.015 R⨀. We also measure a stellar rotation period at Prot = 49.9 ± 5.5 days, an upper limit to its XUV (5–920 Å) flux informed by new Hubble/STIS data, and, for the first time, a variety of element abundances (Fe, Mg, Si, V, Sr, Zr, Rb) and C/O ratio. Moreover, we imposed restrictive constraints on the presence of additional components, either stellar or sub-stellar, in the system. With the input stellar parameters and the radial-velocity and transit data, we determine the radius and mass of the planet Gl 486 b at Rp = 1.343+0.063-0.062 R⨀ and Mp = 3.00+0.13-0.13 M⨁, with relative uncertainties of the planet radius and mass of 4.7% and 4.2%, respectively. From the planet parameters and the stellar element abundances, we infer the most probable models of planet internal structure and composition, which are consistent with a relatively small metallic core with respect to the Earth, a deep silicate mantle, and a thin volatile upper layer. With all these ingredients, we outline prospects for Gl 486 b atmospheric studies, especially with forthcoming James Webb Space Telescope (Webb) observations.
The Transiting Exoplanet Survey Satellite (TESS) provides a continuous suite of new planet candidates that need confirmation and precise mass determination from ground-based observatories. This is ...the case for the G-type star TOI-1710, which is known to host a transiting sub-Saturn planet (Mp = 28.3 ± 4.7 M⊕) in a long-period orbit (P = 24.28 days). Here we combine archival SOPHIE and new and archival HARPS-N radial velocity data with newly available TESS data to refine the planetary parameters of the system and derive a new mass measurement for the transiting planet, taking into account the impact of the stellar activity on the mass measurement. We report for TOI-1710b a radius of Rp = 5.15 ± 0.12 R⊕, a mass of Mp = 18.4 ± 4.5 M⊕, and a mean bulk density of ρp = 0.73 ± 0.18 g cm−3, which are consistent at 1.2σ, 1.5σ, and 0.7σ, respectively, with previous measurements. Although there is not a significant difference in the final mass measurement, we needed to add a Gaussian process component to successfully fit the radial velocity dataset. This work illustrates that adding more measurements does not necessarily imply a better mass determination in terms of precision, even though they contribute to increasing our full understanding of the system. Furthermore, TOI-1710b joins an intriguing class of planets with radii in the range 4–8 R⊕ that have no counterparts in the Solar System. A large gaseous envelope and a bright host star make TOI-1710b a very suitable candidate for follow-up atmospheric characterization.
The present work reports the analysis of the morphology, structure, optical properties, and photocatalytic performance of
Selaginella lepidohylla
-mediated ZnO nanoparticles (NPs). The ZnO NPs were ...obtained using varying concentrations of
Selaginella lepidophylla
as a chelating agent. The morphological analysis confirmed spherical shape and sizes of 19.86–27.75 nm for the obtained ZnO. The structural analysis revealed a hexagonal wurtzite phase and high crystallinity. Additionally, bandgap values of 2.7 eV to 2.9 eV were calculated through analysis of the optical properties. Elemental analysis identified the main Zn, O and C peaks, as well as oxygen vacancies in the ZnO lattice. The UV photocatalytic performance of the ZnO NPs was evaluated through the discoloration of RhB as a model organic pollutant. The ZD4 sample demonstrated the best results with 99.7% dye removal after 180 min, showing excellent potential for other applications.
ABSTRACT
We report the discovery of a planetary system orbiting TOI-763(aka CD-39 7945), a V = 10.2, high proper motion G-type dwarf star that was photometrically monitored by the TESS space mission ...in Sector 10. We obtain and model the stellar spectrum and find an object slightly smaller than the Sun, and somewhat older, but with a similar metallicity. Two planet candidates were found in the light curve to be transiting the star. Combining TESS transit photometry with HARPS high-precision radial velocity (RV) follow-up measurements confirm the planetary nature of these transit signals. We determine masses, radii, and bulk densities of these two planets. A third planet candidate was discovered serendipitously in the RV data. The inner transiting planet, TOI-763 b, has an orbital period of Pb = 5.6 d, a mass of Mb = 9.8 ± 0.8 M⊕, and a radius of Rb = 2.37 ± 0.10 R⊕. The second transiting planet, TOI-763 c, has an orbital period of Pc = 12.3 d, a mass of Mc = 9.3 ± 1.0 M⊕, and a radius of Rc = 2.87 ± 0.11 R⊕. We find the outermost planet candidate to orbit the star with a period of ∼48 d. If confirmed as a planet, it would have a minimum mass of Md = 9.5 ± 1.6 M⊕. We investigated the TESS light curve in order to search for a mono transit by planet d without success. We discuss the importance and implications of this planetary system in terms of the geometrical arrangements of planets orbiting G-type stars.
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