Exoplanet discovery has grown more quickly in recent years. However, the nature of their discovery leaves many unanswered in questions regarding exoplanetary habitability. Proxima Centauri b, an exoplanet which orbits the Sun's closest stellar neighbour, Proxima Centauri, was recently discovered with a subzero equilibrium temperature. Although not considered habitable based on the classical definition of the liquid water range, there may be fractions of Proxima Centauri b which are habitable. A prior study simulated the climate conditions of Proxima Centauri b until equilibrium was reached, using a variety of initial conditions. In this project, various metrics for calculating the fractional habitability of Proxima Centauri b are presented and applied to the results of the prior study's simulations. Colormaps are used to show the ice and temperature distributions that produce the calculated values of fractional habitability. The fractional habitabilities calculated show that while the value is both case and metric dependent, for the vast majority of all cases and metrics the value is nonzero implying that Proxima Centauri b is likely to have habitable regions. / Upptäckandet av exoplaneter har ökat i takt över de senaste åren. Samtidigt, på grund av sättet som de upptäcks finns många obesvarade frågor angående planeternas beboelighet. Proxima Centauri b är en exoplanet som kretsar kring solens närmsta granne, Proxima Centauri. Exoplaneten upptäcktes nyligen med en jämviktstemperatur under $0\degree$C. Trots att exoplaneten inte anses beboelig enligt klassisk definition kan det finnas delar av Proxima Centauri b som är beboeliga. En tidigare studie simulerade klimatförhållandena av Proxima Centarui b till jämvikt nåddes, med varierade begynnelsetillstånd. I detta projekt beräknas andelen av Proxima Centauri b som är beboelig genom flera olika mått för "fractional habitability". Måtten jämförs med den tidigare studien och dess simuleringar. Grafiskt åsikdligörs resultaten via färgkartor över planeten för istjocklek och yttemperatur. De beräknade värdena på Proxima Centauri b's "fractional habitability" påvisar beroende på mått och begynnelsetillstånd. Däremot, för en majoritet av både fall och mått är värdet nollskilt vilket antyder att Proxima Centauri b är delvist beboelig.

Since the construction of the IceCube Neutrino Observatory was completed in 2010, many amazing discoveries have been made in the field of neutrino physics. Recently a neutrino event has been linked to an blazar-type active galactic nucleus source, bringing us one step closer to understanding the production of high-energy extragalactic neutrinos and ushering in a new era of multimessenger astronomy. This was found by linking the neutrino event to one of the Fermi Collaboration’s gamma ray sources which had a blazar counterpart. The quest to link other neutrino events to AGN (active galactic nuclei) sources through collaboration with the Fermi Large Area Telescope has turned up some interesting candidates. The fact that some of these potential sources are not blazars is curious and, although unconfirmed as neutrino sources, these objects merit further investigation due to their unusual nature.

The aim of this master thesis is to investigate the influence of intergalactic duston astronomical observations. The current cosmological paradigm of an acceleratingcosmic expansion is supported by observations of Type Ia supernovae. However, thelight emitted by these and other cosmological sources is not only redshifted by cosmicexpansion but will also interact with matter along the light path which affects the light.Especially intergalactic dust can lead to additional reddening and dimming of distantsources due to light scattering or absorption. This yields systematic contaminations tocosmological measurements. Using quasars as backlight sources we seek to estimate theattenuation of their observed spectra caused by intergalactic dust in order to determinethe existence and properties of the intergalactic dust. In this thesis we will analysethe methods and tools used as well as discussing the dust properties and how theyaffect the results. This thesis shows that intergalactic dust exist, and has a notableeffect on cosmological measurements and favors dust grains consisting of silicate witha size around 0.1 µm with Ωdust around 5 − 7 × 10^−6. The conclusion is in agreementwith previous studies of the same matter. With the increasing precision of cosmologicalmeasurements systematic effects such as intergalactic dust is a factor that has to betaken into account. / Syftet med denna masteruppsats är att undersöka de effekter intergalaktiskt stofthar på astronomiska observationer. Den ledande kosmologiska moddellen som säger attuniversum expanderar är stöttad av observationer av Typ 1a supernovor. Ljuset somkommer från supernovorna är däremot inte bara påverkade av den kosmiska expansionen men kommer också interagera med materia på vägen som påverkar ljuset. Specielltintergalaktiskt stoft kan leda till ytterligare dimning av ljuset och att ljuset blir rödare.Detta är på grund av spridningen eller absorptionen av ljuset när ljuset interagerar medstoftpartiklarna. Detta leder till systematiska fel i kosmologiska mätningar. Genomatt använda kvasarer som en ljuskälla försöker vi uppskatta ljusdämpningen på derasspektrum som orsakats av intergalaktiskt stoft. Detta görs för att bestämma ifall intergalaktiskt stoft existerar och vad dess egenskaper är. I denna uppsats gjordes enanalys av metoden, beräkningsverktygen som användes och några egenskaper hos stoft.Slutsatsen av denna analys visar på att intergalaktiskt stoft existerar och har en mätbar effekt på kosmologiska observationer. Resultatet visar att modellen föredrar stoftav silikat med storlekar runt 0.1 µm med Ωdust runt 5 − 7 × 10^−6vilket stämmer överens med tidigare studier. Med den ökade pressionen av kosmologiska mätningar blirsystematiska effekter, som den från intergalaktiskt stoft, ännu viktigare att ta i hänsyn.

Astronomi fascinerar många och har spelat en avgörande roll i fysikens utveckling. I det svenska gymnasiets läroplan Gy2011 ingår astronomi i kursen Fysik 2. Tidigare intervjustudier har visat att lärare som undervisar i Fysik 2 ofta ger astronomidelen låg vikt och att den ofta knyts starkt till lärobokens innehåll. Det senare gör det intressant att granska hur de aktuella läroböckerna i Fysik 2 behandlar den astronomiska delen av denna kurs. I detta arbete granskas illustrationer ur astronomikapitlen i fyra läroböcker i Fysik 2 utgivna 2012-2019. För att avgöra vilka möjligheter illustrationerna erbjuder att urskilja detaljer som är relevanta för ämnet används begreppen affordans, disciplinär urskiljning och variation. Med dessa begrepp som stöd granskas ett urval av illustrationer (ett fotografi av den variabla stjärnan RS Puppis, bilder av Krabbnebulosan i olika våglängdsområden respektive tre versioner av hubblediagrammet). En del illustrationer visar sig ha lågt pedagogiskt värde, vilket beror på att de inte valts ändamålsenligt eller på att de kopplas svagt till omgivande text. Storleken hos synfältet i de sammanlagt 42 astronomiska bilder (t.ex. fotografier) som finns i kapitlen granskas också. Synfältets bredd i bilderna sträcker sig från 0,000002' till 120 grader (med medianvärdet 12') men synfältens storlek kommenteras inte i kapiteltexterna och variationen används inte för något pedagogiskt syfte.

Charge transfer reactions and their rates play a key role in correctly estimating element abundances in astrophysical objects such as supernovae. The reaction $C + O^+ \rightarrow C^+ + O(^1D) + \Delta E$ has been shown to be of significance when estimating oxygen abundances through model spectrum evaluations, and the relative rate of this reaction can under certain circumstances completely dictate the neutralization rate of oxygen ions. In this project, the rate of this reaction for four different temperatures is estimated using the Olson-Demkov model to calculate the cross section of the reaction as well as calculating rates for a few more reactions to compare to established literature values.  We find that the Olson-Demkov model produces good estimates for reactions that have small energy defects (within an order of magnitude of more rigorous quantum mechanical calculations), but the model underestimates the rate coefficient by several orders of magnitude as the energy defect increases. As the investigated reactions are all exothermic, the energy defect is the released energy from the reaction (i.e., the energy defect is positive). It is also found in most cases that the Olson-Demkov model rate is poorly estimated by the rate coefficient based only on the cross section at the mean velocity, caused by the cross section rising rapidly for velocities higher than the mean. The rate estimates produced for C+O$^+$ are also likely to be underestimated, especially for the temperatures 100 and 1000 Kelvin. No literature comparison is available for this specific reaction, but this conclusion is consistent with the other investigated reactions. / Supernovor är bland de mest extrema fenomen vi kan observera i hela Universum. Dessa våldsamma explosioner lämnar spår efter sig i många år och har varit ovärdeliga objekt att observera för att lära oss mer hur vår galax och Universum har utvecklats över tid. Ljuset från supernovor och deras kvarlevor kan analyseras för att ta reda på vad för ämnen som finns kvar eller som har bildats av både explosionen och de processer som ägt rum efteråt. En typ av reaktion som är viktig för att fullt ut förstå dessa miljöer är så kallade "laddningsöverföringar", en reaktion där en laddad och en oladdad partikel interagerar med varandra varvid laddningen förflyttas mellan de två. Detta projekt har fokuserat på en modell som avser att räkna ut uppskattningar på hur sannolikt det är för dessa reaktioner att äga rum. Modellen, som kallas för Olson-Demkov-modellen, har även jämförts med andra modeller för att se under vilka förhållanden som den fungerar.

Context. Theoretical studies predict that the length scale of convection in stellar atmospheres isproportional to the pressure scale height, which implies that giant and supergiant stars should have convection granules of sizes comparable to their radii. Numerical simulations and the observation of anisotropies on stellar discs agree well with this prediction. Aims. To measure the characteristic sizes of convection structures of models simulated with the CO5BOLD code, to look at how they vary between models and to study their limitations due to numerical resolution. Methods. Fourier analyses are performed to frames from the models to achieve spatial spectral power distributions which are averaged over time. The position of the main peak and the averagevalue of the wavevector are taken as indicators of these sizes. The general shape of the intensity map of the disc in the frame is fitted and subtracted so that it does not contaminate the Fourier analysis. Results. A general relationship of the convection granule size being more or less ten times larger than the pressure length scale is found. The expected wavevector value of the time-averaged spectral power distributions is higher than the position of the main peak. Loose increasing trends with the characteristic sizes by the pressure scale height increasing against stellar mass, radius, luminosity,temperature and gravity are found, while a decreasing trends are found with the radius and modelresolution. Bad resolution subtracts signals on the slope at the side of the main peak towards larger wavevector values and in extreme cases it creates spurious signal towards the end of the spectrum due to artifacts appearing on the frames. Conclusions. The wavevector position of the absolute maximum in the time-averaged spectral power distribution is the best measure of the most prominent sizes in the stellar surfaces. The proportionality constant between granule size and pressure length scale is of the same order ofmagnitude as the one in the literature, however, models present sizes larger than the ones expected, likely because the of prominent features do not correspond to convection granules but to larger features hovering above them. Further studies on models with higher resolution will help in drawing more conclusive results. Appendix. The SIA pipeline takes a set of time-dependent pictures of stellar disks and uses a Fourier Analysis to measure the characteristic sizes of their features and other useful quantities, such as standard deviations or the spatial power distributions of features. The main core of the pipeline consists in identifying the stellar disc in the frames and subtracting their signal from the spatial power distributions through a general fit of the disc intensity. To analyze a time sequence, the SIA pipeline requires at least two commands from the user. The first commandorders the SIA pipeline to read the .sav IDL data structure file where the frame sequence is stored and to produce another .sav file with information on the spectral power distributions, the second command orders the reading of such file to produce two more .sav files, one containing time-averaged size measurements and their deviations while the other breaking down time-dependant information and other arrays used for the calculations. The SIA pipeline has been entirely written in Interactive Data Language (IDL). Most of the procedures used here are original from the SIA pipeline, but a small handfull like ima3_distancetransform.pro, power2d1d.pro, extremum.pro and smooth2d.pro from Bernd Freytag and peaks.pro and compile opt.pro amongst others are actually external. / <p>The report consists in two parts:</p><p>1.- The main project, where we apply our pipeline and get scientific results.</p><p>2.- The appendix, where a technical description of the pipeline is given.</p>

In this work, the efficiency of the LUMBA UVES pipeline for processing of spectroscopic observations is tested by use on 23 high-resolution spectra of the open star cluster M67. An abundance trend discovered by Gavel et al. (2019) concerning iron abundances of giant and sub-giant stars of that cluster is examined. An initial run for a set of ”Gaia FGK benchmark stars”, as described in Blanco-Cuaresma et al. (2014) and Heiter et al. (2015) helps inspect the structure, method and output of the pipeline. Through Python language programming, processes are greatly automatized and the pipeline is run for a total of 460 weak and strong iron lines of our 23-star sample. The line fitting and efficiency of the pipeline is appreciated by statistically analyzing the results and looking into individual discrepant ones. The abundance trend is reproduced while using FeI lines, unlike runs using FeII lines. Trends in abundance over line strength plots also hint at bias through the Gaia-Eso Survey (GES) microturbulence relation. Using internal Data Release 6 (iDR6) and LUMBA-derived starting parameters, log(g) - Teff plots of our sample stars agree with a previously established 4.3 Gyr cluster age. An alternate run is performed for those stars, using LUMBA-derived starting parameters. The choice of starting parameters does impact abundance derivation, but is not the primary source of persistent systematic discrepancies.

A supernova (SN) is the explosive destruction of a star. Via a luminous outpouring of radiation, the SN can rival the brightness of its SN host galaxy for months or years. In the past decade, astronomical surveys regularly observing the sky to deep limiting magnitudes have revealed that core collapse SNe (the demises of massive stars) are sometimes preceded by eruptive episodes by the progenitor stars during the years before the eventual SN explosion. Such SNe tend to show strong signatures of interaction between the SN ejecta and the circumstellar medium (CSM) deposited by the star before the SN explosion, likely by mass-loss episodes like the ones we have started to observe regularly. The complex CSM resolved around certain giant stars in our own galaxy and the eruptions of giant stars like η Car in the 19th century can be seen in this context. As the SN ejecta of an interacting SN sweep up the CSM of the progenitor, radiation from this process offers observers opportunity to scan the late mass loss history of the progenitor. In this thesis, interacting SNe and eruptive mass loss of their progenitors is discussed. The SN iPTF13z (discovered by the intermediate Palomar Transient Factory, iPTF) is presented. This transient was followed with optical photometry and spectroscopy during 1000 days and displayed a light curve with several conspicuous re-brigthenings ("bumps"), likely arising from SN ejecta interacting with denser regions in the CSM. Around 200 days before discovery, in archival data we found a clear precursor outburst lasting &gt;~ 50 days. A well-observed (but not necessarily well understood) event like SN 2009ip, which showed both precursor outbursts and a light curve bump, makes an interesting comparison object. The embedding of the (possible) SN in a CSM makes it hard to tell if a destructive SN explosion actually happened. In this respect, iPTF13z is compared to e.g. SN 2009ip but also to long-lived interacting SNe like SN 1988Z. Some suggestions for future investigations are offered, to tie light curve bumps to precursor events and to clarify the question of core collapse in the ambiguous cases of some interacting SNe.

In this licentiate thesis, I consider debris disks from an observational, astronomical viewpoint, but also discuss a potential astrobiological application. Debris disks are essentially disks of dust and rocks around main-sequence stars, analogue to the Kuiper- or the asteroid belt in our solar system. Their observation and theoretical modeling can help to constrain planet formation models and help in the understanding of the history of the solar system. After a general introduction into the field of debris disks and some basic debris disk physics, the thesis concentrates on the observation of gas in debris disks. The possible origins of this gas and its dynamics are discussed and it is considered what it can tell us about the physical conditions in the disk and possibly about the dust composition. In this way, the paper associated with this thesis (dealing with the gas in the β Pic debris disk) is set into context. More in detail, we observed the CII emission originating from the carbon-rich β Pic disk with Herschel HIFI and attempted to constrain the spatial distribution of the gas from the shape of the emission line. This is necessary since the gas production mechanism is currently unknown, but can be constraint by obtaining information about the spatial profile of the gas. The last part of the thesis describes our preliminary studies of the possibility of a debris disk containing biomarkers, created by a giant impact on a life-bearing exoplanet.

Dark matter has a long history, but it was not until modern times that we have a chance of detecting it. This thesis focuses on the velocity distribution and its effect on indirect WIMP detection. Recently a new velocity distribution, based on data from SDSS and GAIA, was proposed. For this reason simulation of capture, annihilation and resulting flux of neutrinos from the Sun and Earth has been made both for the new and Maxwell-Boltzmann velocity distribution. The newly proposed velocity can reduce the annihilation rate in Earth by two thirds. For the Sun the effect depends on the mass of the WIMPs. For 50 GeV WIMPs the newly proposed velocity distribution could increase the annihilation rate by 5%, while for 3 TeV WIMPs it could decrease the annihilation rate by 28%. For Earth and high mass WIMPs the low velocity tail is the important part and the low resolution of this region in the new velocity distribution result in some uncertainties.