Astrobiological Effects of F, G, K and M Main-Sequence Stars

We focus on the astrobiological effects of photospheric radiation produced by main-sequence stars of spectral types F, G, K, and M. The photospheric radiation is represented by using realistic spectra, taking into account millions or hundred of millions of lines for atoms and molecules. DNA is taken as a proxy for carbon-based macromolecules, assumed to be the chemical centerpiece of extraterrestrial life forms. Emphasis is placed on the investigation of the radiative environment in conservative as well as generalized habitable zones.Comment: 3 pages, 3 figures; submitted to: Exoplanets: Detection, Formation and Dynamics, IAU Symposium 249, eds. Y.S. Sun and S. Ferraz-Mello (San Francisco: Astr. Soc. Pac.

Planet-Induced Emission Enhancements in HD 179949: Results from McDonald Observations

We monitored the Ca II H and K lines of HD 179949, a notable star in the southern hemisphere, to observe and confirm previously identified planet induced emission (PIE) as an effect of star-planet interaction. We obtained high resolution spectra (R ~ 53,000) with a signal-to-noise ratio S/N >~ 50 in the Ca II H and K cores during 10 nights of observation at the McDonald Observatory. Wide band echelle spectra were taken using the 2.7 m telescope. Detailed statistical analysis of Ca II K revealed fluctuations in the Ca II K core attributable to planet induced chromospheric emission. This result is consistent with previous studies by Shkolnik et al. (2003). Additionally, we were able to confirm the reality and temporal evolution of the phase shift of the maximum of star-planet interaction previously found. However, no identifiable fluctuations were detected in the Ca II H core. The Al I lambda 3944 A line was also monitored to gauge if the expected activity enhancements are confined to the chromospheric layer. Our observations revealed some variability, which is apparently unassociated with planet induced activity.Comment: 11 pages, 11 figures, 5 tables; Publications of the Astronomical Society of Australia (in press

Modelling the light-curve of KIC 12557548b: an extrasolar planet with a comet like tail

An object with a very peculiar light-curve was discovered recently using Kepler data. Authors argue that this object may be a transiting disintegrating planet with a comet like dusty tail. We calculate the light-curves of stars with such planets and take into account the Mie absorption and scattering on spherical dust grains of various sizes assuming realistic dust opacities and phase functions and finite radius of the source of the scattered light. The planet light-curve is reanalysed using long and short cadence Kepler observations from the first 14 quarters. Orbital period of the planet was improved. We prove that the peculiar light-curve of this objects is in agreement with the idea of a planet with a comet like tail. There is an evidence of a quasi periodic long term evolution of the tail. Light-curve has a prominent pre-transit brightening and a less prominent post-transit brightening. Both are caused by the forward scattering and are a strong function of the particle size. This feature enabled us to estimate a typical particle size (radius) in the dust tail of about 0.1-1 micron. However, there is an indication that the particle size changes along the tail. Larger particles better reproduce the pre-transit brightening and transit core while smaller particles are more compatible with the egress and post-transit brightening. Dust density in the tail is a steep decreasing function of the distance from the planet which indicates a significant tail destruction caused by the star. We also argue that the 'planet' does not show uniform behaviour but may have at least two constituents. This light-curve with pre-transit brightening is analogous to the light-curve of $\epsilon$ Aur with mid-eclipse brightening and forward scattering plays a significant role in such eclipsing systems.Comment: Version 2: Submitted to A&A, any comments are welcome. Version 1: Presented at the meeting: The Most Mysterious Binaries: Significance for Astrophysics, Hvar, Croatia, July 2-6, 201

Signatures of Star-planet interactions

Planets interact with their host stars through gravity, radiation and magnetic fields, and for those giant planets that orbit their stars within $\sim$10 stellar radii ($\sim$0.1 AU for a sun-like star), star-planet interactions (SPI) are observable with a wide variety of photometric, spectroscopic and spectropolarimetric studies. At such close distances, the planet orbits within the sub-alfv\'enic radius of the star in which the transfer of energy and angular momentum between the two bodies is particularly efficient. The magnetic interactions appear as enhanced stellar activity modulated by the planet as it orbits the star rather than only by stellar rotation. These SPI effects are informative for the study of the internal dynamics and atmospheric evolution of exoplanets. The nature of magnetic SPI is modeled to be strongly affected by both the stellar and planetary magnetic fields, possibly influencing the magnetic activity of both, as well as affecting the irradiation and even the migration of the planet and rotational evolution of the star. As phase-resolved observational techniques are applied to a large statistical sample of hot Jupiter systems, extensions to other tightly orbiting stellar systems, such as smaller planets close to M dwarfs become possible. In these systems, star-planet separations of tens of stellar radii begin to coincide with the radiative habitable zone where planetary magnetic fields are likely a necessary condition for surface habitability.Comment: Accepted for publication in the handbook of exoplanet

Viðhorf foreldra til ferilmöppu barna : brúin milli heimilis og leikskóla

This qualitative interview research was conducted to discover parent´s views and experiences with childrens´ portfolios in the preschool Aðalborg. The portfolios, implemented in 2017, are based on the communication books maintained by preschool educators, bilingual and multilingual children, and their parents. Parent contribution has been and continues to be essential in creating the content of the portfolios. The aim of the research is to improve upon the application portfolios play in giving parents insight into the preschool curriculum and goals, and to participate in an active way in assessing their child´s learning and wellbeing. An interview with the preschool´s principal was conducted prior to the interviews with parents to shed light on the motive and goals of the portfolios, her expectations, and further considerations on how the implementation has been working. Interviews with the parents of six children were initially planned. Due to covid, schedules and situations changed, and one additional interview was recorded to generate sufficient data. Because of the multicultural profile of the preschool, interviews were conducted with four parents with a diverse cultural background and three native Icelandic parents. Parents were asked if they could monitor and assess their children´s learning and wellbeing through the portfolio entries and share their experiences looking at and contributing to the portfolios with their children. Findings of the study reveal the parents´ joy and appreciation of the portfolios. The parents claimed the most important feature of the portfolios is their function as a narrative tool, which children can use to describe their preschool life to their parents and vice versa. Parents also value having information about the kinds of activities their children are participating in and what they are experiencing at preschool. Due to their personal nature parents prefer portfolios over receiving pictures of their children in newsletters, emails, and online apps. Majority of the parents can observe their children´s progress, learning and preschools´ practices through the portfolios. However, some parents brought up some important aspects such as participation of children in selecting the material for the portfolios and in what ways they could monitor their children´s well-being. Parents were also asked what kind of content they would like to see in the portfolios. Though most are satisfied with the content, their suggestions about „everyday activities“ and „play documentations“ should be taken into consideration to improve portfolios´ usage in documenting children´s own field of interest and social interactions. Most of the parents and the preschool principal agreed on the desirability to send the portfolios home with the children more often.Þessi eigindlega viðtalsrannsókn var gerð til að kanna viðhorf og reynslu foreldra af ferilmöppum barna í leikskólanum Aðalborg. Ferilmöppurnar, sem voru innleiddar árið 2017 eru byggðar á samskiptabókum sem leikskólakennarar, tvítyngd og fjöltyngd börn og foreldrar þeirra héldu utan um. Foreldraframlag hefur verið og er enn ómissandi þáttur við að búa til innihald ferilmappnanna. Markmið rannsóknarinnar var að efla hlutverk ferilmöppurnar að gefa foreldrum innsýn í námskrá og markmið leikskólans og hvetja þau í að taka virkan þátt í mati á námi og líðan barnsins síns. Tekið var viðtal við leikskólastjóra til að varpa ljósi á tilefni og markmið ferilmöppunnar, væntingar hennar og nánari skoðun á því hvernig framkvæmdin hefur gengið. Í framhaldi voru tekin viðtöl við foreldra. Í upphafi voru áformuð viðtöl við foreldra sex barna. Vegna Covid breyttust tímasetningar og aðstæður og eitt viðtal til viðbótar var tekið upp til að afla nægjanlegra gagna. Vegna fjölmenningarlegs eðlis leikskólans voru tekin viðtöl við fjóra foreldra með fjölbreyttan menningarbakgrunn og þrjá innfædda íslenska foreldra. Foreldrar voru spurðir hvort þeir gætu fylgst með og metið nám og líðan barna sinna í gegnum ferilmöppurnar og deilt reynslu sinni af því að skoða og taka þátt að setja efni í ferilmöppunnar með börnunum sínum. Niðurstöður rannsóknarinnar sýna gleði og þakklæti foreldra með ferilmöppurnar. Foreldrarnir fullyrtu að mikilvægasti eiginleiki möppunnar væri hún væri frásagnartæki sem börn geta notað til að lýsa leikskólalífi sínu fyrir foreldrum sínum og öfugt. Foreldrar meta einnig að hafa aðgang að upplýsingum um hvers konar starfsemi börnin þeirra taka þátt í og hvað þau eru að upplifa í leikskólanum. Vegna persónulegs eðlis þeirra kjósa foreldrar ferilmöppunar fram yfir að fá myndir af börnum sínum í fréttabréfum, tölvupósti og netforritum. Meirihluti foreldra getur fylgst með framförum barna sinna, námi og starfsháttum leikskóla í gegnum möppurnar. Sumir foreldrar tóku þó upp mikilvæg atriði eins og þátttöku barna í vali á efni sem fer í möppurnar og með hvaða hætti þeir gætu fylgst með líðan barna sinna. Foreldrar voru einnig spurðir hvers konar efni þeir myndu vilja sjá í möppunum. Þrátt fyrir að flestir séu ánægðir með innihaldið, ætti að taka tillit til ábendinga þeirra um „daglega athöfn“ og „leikskráningar “ til að bæta notkun ferilmappnanna við skráningu á áhugasviði og félagslegum samskiptum barna. Flestir foreldrar og leikskólastjóri voru sammála um að æskilegt væri að senda möppurnar heim með börnunum oftar

Oxidative Stress Parameters, Selenium Levels, DNA Damage, and Phthalate Levels in Plastic Workers.

Di(2-ethylhexyl)phthalate (DEHP) is the most widely used phthalate. DEHP is highly used in PVC floorings and PVC windows and carpeting. The objective of this study was to determine sex hormone levels, oxidative stress parameters, selenium levels, DNA damage, and phthalate levels in plastics workers (n = 24, age = 20-58 years) working in the production of rubber mechanical goods and exposed to DEHP in workplace. The control group (n = 29, age = 25-54, all male) was selected from age-matched healthy adults. Antioxidant parameters and DNA damage were determined by spectrophotometry. Selenium levels were determined by atomic absorption spectroscopy. Plasma hormone levels were measured by chemiluminescence microparticle immunoassay. Plasma phthalate levels were determined by high-pressure liquid chromatography. Plastic workers had lower serum testosterone and free T4 levels and higher follicle-stimulating hormone levels vs. controls. Liver enzyme activities were markedly higher in workers vs. controls. There were also increases in plasma glutathione peroxidase levels and marked decreases in plasma selenium and erythrocyte total glutathione levels in plastics workers (P < 0.05 vs. control). Plasma 8-hydroxy-2'-deoxyguanosine levels were 14-fold higher in plastics workers than in controls. Plasma DEHP and mono(2-ethylhexyl)phthalate were also markedly higher in workers vs. controls. The results of this study show that occupational exposure to DEHP may lead to disturbances in sex hormones, increased liver problems, higher oxidative stress and DNA damage levels, and lower trace element concentrations in workers. More comprehensive and mechanistic studies with higher numbers of subjects are needed to show the unwanted effects of occupational exposure to DEHP

Oxidative Stress Parameters, Selenium Levels, DNA Damage, and Phthalate Levels in Plastic Workers.

Di(2-ethylhexyl)phthalate (DEHP) is the most widely used phthalate. DEHP is highly used in PVC floorings and PVC windows and carpeting. The objective of this study was to determine sex hormone levels, oxidative stress parameters, selenium levels, DNA damage, and phthalate levels in plastics workers (n = 24, age = 20-58 years) working in the production of rubber mechanical goods and exposed to DEHP in workplace. The control group (n = 29, age = 25-54, all male) was selected from age-matched healthy adults. Antioxidant parameters and DNA damage were determined by spectrophotometry. Selenium levels were determined by atomic absorption spectroscopy. Plasma hormone levels were measured by chemiluminescence microparticle immunoassay. Plasma phthalate levels were determined by high-pressure liquid chromatography. Plastic workers had lower serum testosterone and free T4 levels and higher follicle-stimulating hormone levels vs. controls. Liver enzyme activities were markedly higher in workers vs. controls. There were also increases in plasma glutathione peroxidase levels and marked decreases in plasma selenium and erythrocyte total glutathione levels in plastics workers (P < 0.05 vs. control). Plasma 8-hydroxy-2'-deoxyguanosine levels were 14-fold higher in plastics workers than in controls. Plasma DEHP and mono(2-ethylhexyl)phthalate were also markedly higher in workers vs. controls. The results of this study show that occupational exposure to DEHP may lead to disturbances in sex hormones, increased liver problems, higher oxidative stress and DNA damage levels, and lower trace element concentrations in workers. More comprehensive and mechanistic studies with higher numbers of subjects are needed to show the unwanted effects of occupational exposure to DEHP

Reply to Deng and Tang.

status: Published onlin