Sökresultat

The project was aimed at numerically assessing exoplanetary systems to distinguish their capabilities of hosting additional planets. The shortcomings of the radial velocity method sometimes causes hindrance in the detection of terrestrial planets. Although modern spectrometers have evolved and improved drastically, the process of distinguishing signals from smaller planets is still difficult and c

Using spectra of RR Lyrae stars in the Small Magellanic Cloud (SMC) a metallicity snapshot from an early epoch in the history of the SMC could possibly be obtained. The SMC, one of our closest neighbours in the Local Group of galaxies, offers the opportunity to study another galaxy close-up. The history of the SMC can be traced using the chemical characteristics of its different generations of sta

Galaxy interactions and mergers are natural recurring events in the current cosmological paradigm, events that often coincide with starbursts and enhanced star formation activity. To understand why that is, one can use idealised (non-cosmological) merger simulations, which provide freedom to recreate specific tidally distorted galaxies, and analysis of the time evolution and underlying physics of

Hot Jupiters are gas giants under intense stellar radiation with short orbital periods of only a few days. Due to their large radii, hot temperatures, and large scale heights, hot Jupiters can be observationally characterised in detail through spectroscopy over an entire orbital phase. Transmission spectroscopy is one of the tools that aid us in understanding the complex chemistry of exoplanet atm

Background. Carlberg & Innanen (1987) first proposed the idea of measuring the solar re- flex velocity (the velocity of the Sun around the galactic centre), Vg,⊙, using the momenta of the stars in the solar neighbourhood. The proposal was a consequence of the work of L. Martinet (Martinet 1974), where he proved that there should be a dearth of stars with zero angular momenta in the solar neigh

Phosphorus-enhanced (P-rich; [P/Fe] ≳ +0.8) giants have been found among mildly metal-poor field stars, but in only one star in a globular cluster (GC), M4 (NGC 6121). Also, in a sample of bulge spheroid stars, some of them showed a moderate P enhancement in the range +0.5 < [P/Fe] < +1.0. In this paper we derive the P abundance of moderately metal-poor ([Fe/H] ≳ −1) GC stars, aiming to check if t

We have for the first time identified the early stellar disk in the Milky Way by using a combination of elemental abundances and kinematics. Using data from APOGEE DR17 and Gaia we select stars in the Mg–Mn–Al–Fe plane with elemental abundances indicative of an accreted origin and find stars with both halo-like and disk-like kinematics. The stars with halo-like kinematics lie along a lower sequenc

Solar mean magnetic field (SMMF) measurements from the Wilcox SolarObservatory and with SOHO/MDI are analyzed using continuous wavelettransforms, SMMF variability is found at a number of temporal scales.Detected SMMF variations with a 1-2 year period is considered to belinked to long-term variations in the internal rotation of the Sun.Intermediate SMMF oscillations with a period of 80-200 days are

We have observed photons in the visible light range emitted from slow (2.0 keV/amu) highly charged Ar6+ ions which have captured one electron and transmitted through a Ni microcapillary target. Observed lines were identified by comparing with an ab initio calculation based on the multi-configuration Hartree-Fock method. (C) 2003 Elsevier Science B.V. All rights reserved.

A study on a possible solar wind interaction with the North AtlanticOscillation (NAO) is performed. Results are presented suggesting arelationship between the NAO index and the electric field strength E ofthe solar wind. A possible scenario for the suggested interaction isthat an electromagnetic disturbance is generated by the solar wind inthe global electric circuit of the ionosphere. This distur

Using geopotential height data we find a strong correlation between theelectric field strength E of the solar wind and pressure variations inthe stratosphere and troposphere. The large-scale evolution of E seemsto influence the stratospheric pressure in both hemispheres with theexception of the polar regions. For the tropospheric pressure theinfluence is concentrated to an area in the northern Atl

We present a method for parametrizing the Zeeman effect in hydrogen-like systems in high-temperature plasmas, where the fine-structure is completely unresolved. The method is based on the observation that the different polarization components behave collectively like separate entities, with simple relations. The entire Zeeman pattern can then be reduced to just three components, whose dependence o

High-resolution spectra of the chemically peculiar HgMn stars chi Lupiand HR 7775, obtained with the Hubble Space Telescope/Goddard HighResolution Spectrograph, are investigated for their abundance of bismuthby comparison with LTE synthetic spectrum modeling. HR 7775, previouslyknown from International Ultraviolet Explorer spectra to display stronglines of Bi II, is determined to have bismuth pres

We revisit the abundances of neutron-capture elements in the metal-poor ([Fe/H] = -2.9) r-process-rich halo star CS 31082-001. Partly motivated by the development of the new near-ultraviolet Cassegrain U-band Efficient Spectrograph for the Very Large Telescope, we compiled an expanded line list for heavy elements over the range 3000-4000 Å, including hyperfine structure for several elements. Combi

Natural lifetimes were measured by time-resolved observation of laser-induced fluorescence. Free Ce, Ce+, and Ce++ particles were obtained in a laser-produced plasma. Lifetimes were measured for eight levels of singly ionized cerium, as well as for nine levels of doubly ionized cerium. The lifetime data were compared with previously published experimental and theoretical results.

23 april 2025 09:00 till 14:00 | Konferens It is once again time for the Innovation Research Day. Last year was the first time this event was held, and it led to interesting discussions and new links between researchers from different disciplines. The Innovation Research Day provides a platform to share and discuss new projects and initiatives, to identify potential interfaces and complementaritie

https://www.lu.se/evenemang/innovation-research-day-0 - 2026-05-28

Global disease transmission is an important area, since knowledge of the time of the onset of an epidemic in a region might help authorities to save many lives. In this thesis I have used a deterministic model with eight parameters, of which two were time dependent, for spreading of the SARS disease. My model is an extension of a model by Colizza and co-workers, where I have added a Heaviside step

Issue of study: Since the World War II scenario planning has existed as a strategic planning tool and during the 1970s Pierre Wack introduced this strategic tool for organisations. Even tough the usage of scenario planning often aims to make better strategic decisions there still does not exist any clear method that is niched towards competition. Therefore a study with the purpose to understand if