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.
Context
. TOI-732 is an M dwarf hosting two transiting planets that are located on the two opposite sides of the radius valley. Inferring a reliable demographics for this type of systems is key to ...understanding their formation and evolution mechanisms.
Aims
. By doubling the number of available space-based observations and increasing the number of radial velocity (RV) measurements, we aim at refining the parameters of TOI-732 b and c. We also use the results to study the slope of the radius valley and the density valley for a well-characterised sample of M-dwarf exoplanets.
Methods
. We performed a global Markov chain Monte Carlo analysis by jointly modelling ground-based light curves and CHEOPS and TESS observations, along with RV time series both taken from the literature and obtained with the MAROON-X spectrograph. The slopes of the M-dwarf valleys were quantified via a support vector machine (SVM) procedure.
Results
. TOI-732b is an ultrashort-period planet (
P
= 0.76837931
-0.00000042
+0.0000039
days) with a radius
R
b
= 1.325
-0.058
+0.057
R
⊕
, a mass
M
b
= 2.46 ± 0.19
M
⊕
, and thus a mean density
ρ
b
= 5.8
-0.8
+1.0
g cm
-3
, while the outer planet at
P
= 12.252284 ± 0.000013 days has
R
c
= 2.39
-0.11
+0.10
R
⊕
,
M
c
= 8.04
-0.48
+0.50
M
⊕
, and thus
ρ
c
= 3.24
-0.43
+0.55
g cm
-3
. Even with respect to the most recently reported values, this work yields uncertainties on the transit depths and on the RV semi-amplitudes that are smaller up to a factor of ~1.6 and ~2.4 for TOI-732 b and c, respectively. Our calculations for the interior structure and the location of the planets in the mass-radius diagram lead us to classify TOI-732 b as a super-Earth and TOI-732 c as a mini-Neptune. Following the SVM approach, we quantified d log
R
p,valley
/ d log
P
= -0.065
-0.013
+0.024
, which is flatter than for Sun-like stars. In line with former analyses, we note that the radius valley for M-dwarf planets is more densely populated, and we further quantify the slope of the density valley as d log ρ^
valley
/ d log
P
= -0.02
-0.04
+0.12
.
Conclusions
. Compared to FGK stars, the weaker dependence of the position of the radius valley on the orbital period might indicate that the formation shapes the radius valley around M dwarfs more strongly than the evolution mechanisms.
Abstract
Kepler 1627A is a G8V star previously known to host a 3.8
R
⊕
planet on a 7.2 day orbit. The star was observed by the Kepler space telescope because it is nearby (
d
= 329 pc) and it ...resembles the Sun. Here, we show using Gaia kinematics, TESS stellar rotation periods, and spectroscopic lithium abundances that Kepler 1627 is a member of the
38
−
5
+
6
Myr old
δ
Lyr cluster. To our knowledge, this makes Kepler 1627Ab the youngest planet with a precise age yet found by the prime Kepler mission. The Kepler photometry shows two peculiarities: the average transit profile is asymmetric, and the individual transit times might be correlated with the local light-curve slope. We discuss possible explanations for each anomaly. More importantly, the
δ
Lyr cluster is one of ∼10
3
coeval groups whose properties have been clarified by Gaia. Many other exoplanet hosts are candidate members of these clusters; their ages can be verified with the trifecta of Gaia, TESS, and ground-based spectroscopy.
We present the characterization of two engineered diffusers mounted on the 2.5-meter Nordic Optical Telescope, located at Roque de Los Muchachos, Spain. To assess the reliability and the efficiency ...of the diffusers, we carried out several test observations of two photometric standard stars, along with observations of one primary transit observation of TrES-3b in the red (R band), one of CoRoT-1b in the blue (B band), and three secondary eclipses of WASP-12b (V band). The achieved photometric precision is in all cases within the submillimagnitude level for exposures between 25 and 180 s. Along with a detailed analysis of the functionality of the diffusers, we add a new transit depth measurement in the blue (B band) to the already observed transmission spectrum of CoRoT-1b, disfavoring a Rayleigh slope. We also report variability of the eclipse depth of WASP-12b in the V band. For the WASP-12b secondary eclipses, we observe a secondary depth deviation of about 5σ, and a difference of 6σ and 2.5σ when compared to the values reported by other authors in a similar wavelength range determined from Hubble Space Telescope data. We further speculate about the potential physical processes or causes responsible for this observed variability.
Teegarden’s Star revisited Dreizler, S.; Luque, R.; Ribas, I. ...
Astronomy and astrophysics (Berlin),
04/2024, Volume:
684
Journal Article, Web Resource
Peer reviewed
Open access
The two known planets in the planetary system of Teegarden’s Star are among the most Earth-like exoplanets currently known. Revisiting this nearby planetary system with two planets in the habitable ...zone aims at a more complete census of planets around very low-mass stars. A significant number of new radial velocity measurements from CARMENES, ESPRESSO, MAROON-X, and HPF, as well as photometry from TESS motivated a deeper search for additional planets. We confirm and refine the orbital parameters of the two know planets Teegarden’s Star b and c. We also report the detection of a third planet d with an orbital period of 26.13 ± 0.04 days and a minimum mass of 0.82 ± 0.17 M ⊕ . A signal at 96 days is attributed to the stellar rotation period. The interpretation of a signal at 172 days remains open. The TESS data exclude transiting short-period planets down to about half an Earth radius. We compare the planetary system architecture of very low-mass stars. In the currently known configuration, the planetary system of Teegarden’s star is dynamically quite different from that of TRAPPIST-1, which is more compact, but dynamically similar to others such as GJ 1002.
Objective
This study aimed to ascertain whether disasters at sea had an enduring traumatic effect on psychological functioning, accident proneness, and on their interest to continue working at sea.
...Method
Crew members of selected sea-disasters were contacted. The chosen disasters were of differing severity and in some cases fatalities had occurred. The disasters had taken place on average 8 years previously. Those who agreed to participate were interviewed in a semi-structured interview. They also answered the CIDI; DIS; GHQ-30; IES, and PTSS-10. One hundred-and-twelve seamen who had been in disasters were compared with a comparison group consisting of 59 peers who had not been in a disaster.
Results
Survivors of fatal disasters experienced more long-lasting negative effects than did others where lives were not lost. They had more frequently unpleasant intrusive thoughts on the IES (
p
< 0.01) compared with their peers. On the DIS, they also more frequently experienced heightened arousal (
p
< 0.001), sleep problems (
p
< 0.01), and nightmares (
p
< 0.01). The duration of PTSD symptoms from the time of the disaster was on average 18 months. Over 33% of the disaster group had experienced some PTSD symptoms within the past 12 months. Disaster survivors had not quit seamanship as frequently as non-disaster seamen.
Conclusion
The most severe and long-lasting symptoms were found among those who had been in disasters where one or more crew members had perished. Loss of life in disasters therefore seems significant in the process of creating or extending the endurance of symptoms of psychological vulnerability.
The Icelandic summer-spawning herring stock collapsed during the late 1960s as a result of a combination of high fishing pressure and deteriorating environmental conditions. Following a moratorium on ...fishing the stock, a small fishery of about 10 000 t started in 1975. From analyses of several harvesting strategies it was decided to recommend fishing at or near F0.1. When the fishery was reopened it was managed by individual non-transferable quotas per boat that gradually developed into an individual transferable quota (ITQ) system. The development, the implementation, and the effect of the harvesting strategy and the management system are discussed and evaluated. Results indicate that a strategy of catching 20% of the adult stock biomass (3-ringers and older) would be useful from the point of view of achieving an optimal sustainable harvest from the stock without risking stock depletion. This is not markedly different from the current exploitation strategy, which has now been very successful for almost a quarter of a century.
Psychosocial stress and health problems Danielsson, Maria; Heimerson, Inger; Lundberg, Ulf ...
Scandinavian journal of public health,
12/2012, Volume:
40, Issue:
9_suppl
Journal Article
Peer reviewed
Stress can be defined as an imbalance between demands placed on us and our ability to manage them. The body's stress system is adapted to confront sudden physical threats. Today, however, we are ...increasingly exposed to prolonged mental and psychosocial stress. Prolonged stress can give rise to a range of problems: poor performance, chronic fatigue, disinterest, dejection, memory disturbances, sleep problems, numbness and diffuse muscle pains. These symptoms may eventually be followed by depression, post-traumatic stress disorder and chronic fatigue syndrome, and ultimately chronic pain conditions, cardiovascular disease and diabetes. Sleep is a vital counterbalance to stress as it enables the body to recover properly. Good sleep is thus essential to our ability to cope with stress and stay healthy. The decline in the mental wellbeing of the population since the 1980s has been accompanied by a rise in the number of pain complaints. A similar development in respect of symptoms such as anxiousness, nervousness and anxiety, constant fatigue and neck and shoulder pain and sleeping problems has been observed in the population. This increase, which continued throughout the 1990s and culminated in 2001, was followed by a slight fall. However, there was no decline among young people in the early 2000s. Rather, the number of complaints continued to increase. Adapted from the source document.
This paper describes a method for the analysis of groundfish survey data by incorporating zero and non-zero values into a single model. This is done by using a model which modifies the ...delta-distribution approach to fit into the GLM framework and uses maximum likelihood to estimate parameters. No prior assumptions of homogeneity are used for the structure of the zero or non-zero values. The method is primarily applicable to fixed-station designs, although extensions to other designs are possible. The maximum likelihood estimation reduces to fitting a GLM to 0/1 values and another GLM to the positive abundance values. The new model is tested on Icelandic groundfish survey data. It is seen that the model can be used for evaluating the effect of different factors on catch rates as well as estimating abundance indices. Results from different models are compared on the basis of tuned VPA runs.
We present the detection of three exoplanets orbiting the early M dwarf TOI-663 (TIC 54962195; V = 13.7 mag, J = 10.4 mag, R ★ = 0.512 ± 0.015 R ⊙ , M ★ = 0.514 ± 0.012 M ⊙ , d = 64 pc). TOI-663 b, ...c, and d, with respective radii of 2.27 ± 0.10 R ⊕ , 2.26 ± 0.10 R ⊕ , and 1.92 ± 0.13 R ⊕ and masses of 4.45 ± 0.65 M ⊕ , 3.65 ± 0.97 M ⊕ , and <5.2 M ⊕ at 99%, are located just above the radius valley that separates rocky and volatile-rich exoplanets. The planet candidates are identified in two TESS sectors and are validated with ground-based photometric follow-up, precise radial-velocity measurements, and high-resolution imaging. We used the software package juliet to jointly model the photometric and radial-velocity datasets, with Gaussian processes applied to correct for systematics. The three planets discovered in the TOI-663 system are low-mass mini-Neptunes with radii significantly larger than those of rocky analogs, implying that volatiles, such as water, must predominate. In addition to this internal structure analysis, we also performed a dynamical analysis that confirmed the stability of the system. The three exoplanets in the TOI-663 system, similarly to other sub-Neptunes orbiting M dwarfs, have been found to have lower densities than planets of similar sizes orbiting stars of different spectral types.
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