Dark influences: imprints of dark satellites on dwarf galaxies

In the context of the current $\Lambda$CDM cosmological model small dark matter haloes are abundant and satellites of dwarf galaxies are expected to be predominantly dark. Since low mass galaxies have smaller baryon fractions interactions with these satellites may leave particularly dramatic imprints. We uncover the influence of the most massive of these dark satellites on disky dwarf galaxies and the possible dynamical and morphological transformations that result from these interactions. We use a suite of carefully set-up, controlled simulations of isolated dwarf galaxies. The primary dwarf galaxies have solely a stellar disk in the dark matter halo and the secundaries are completely devoid of baryons. We vary the disk mass, halo concentration, initial disk thickness and inclination of the satellite orbit. The disky dwarf galaxies are heated and disrupted due to the minor merger event, more extremely for higher satellite over disk mass ratios, and the morphology and kinematics are significantly altered. Moreover, for less concentrated haloes the minor merger can completely destroy the disk leaving a low-luminosity spheroidal-like galaxy instead. We conclude that dwarf galaxies are very much susceptible to being disturbed by dark galaxies and that even a minor merger event can significantly disrupt and alter the structure and kinematics of a dwarf galaxy. This process may be seen as a new channel for the formation of dwarf spheroidal galaxies.Comment: 16 pages, 13 figures, A&A accepted. For movies or a higher resolution version see http://www.astro.rug.nl/~starkenb/dwarfsanddarks.htm

Dark influences III. Structural characterization of minor mergers of dwarf galaxies with dark satellites

In the current concordance cosmology small halos are expected to be completely dark and can significantly perturb low-mass galaxies during minor merger interactions. These interactions may well contribute to the diversity of the dwarf galaxy population. Dwarf galaxies in the field are often observed to have peculiarities in their structure, morphology, and kinematics, as well as strong bursts of star formation without apparent cause. We aim to characterize the signatures of minor mergers of dwarf galaxies with dark satellites to aid their observational identification. We explore and quantify a variety of structural, morphological, and kinematic indicators of merging dwarf galaxies and their remnants using a suite of hydrodynamical simulations. The most sensitive indicators of mergers with dark satellites are large asymmetries in the gaseous and stellar distributions, enhanced central surface brightness and starbursts, and velocity offsets and misalignments between the cold gas and stellar components. In general, merging systems span a wide range of values of the most commonly used indicators, while isolated objects tend to have more confined values. Interestingly, we find in our simulations that a significantly off-centered burst of star formation can pinpoint the location of the dark satellite. Observational systems with such characteristics are perhaps the most promising for unveiling the presence of the hitherto, missing satellites.Comment: 9 pages, 7 figures. Accepted in A&

More pieces of the puzzle: Chemistry and substructures in the Galactic thick disk

We present a study of the chemical abundances of Solar neighbourhood stars associated to dynamical structures in the Milky Way's (thick) disk. These stars were identified as overdensity in the eccentricity range 0.3< ecc < 0.5 in the Copenhagen-Geneva Survey by Helmi et al. (2006). We find that the stars with these dynamical characteristics do not constitute a homogeneous population. A relatively sharp transition in dynamical and chemical properties appears to occur at a metallicity of [Fe/H] ~ -0.4. Stars with [Fe/H] > -0.4 have mostly lower eccentricities, smaller vertical velocity dispersions, are alpha-enhanced and define a rather narrow sequence in [alpha/Fe] vs [Fe/H], clearly distinct from that of the thin disk. Stars with [Fe/H] < -0.4 have a range of eccentricities, are hotter vertically, and depict a larger spread in [alpha/Fe]. We have also found tentative evidence of substructure possibly associated to the disruption of a metal-rich star cluster. The differences between these populations of stars is also present in e.g. [Zn/Fe], [Ni/Fe] and [SmII/Fe], suggesting a real physical distinction.Comment: Astrophysical Journal in press. 5 pages, 4 figure

Dark influences II. Gas and star formation in minor mergers of dwarf galaxies with dark satellites

Context. It has been proposed that mergers induce starbursts and lead to important morphological changes in galaxies. Most studies so far have focused on large galaxies, but dwarfs might also experience such events, since the halo mass function is scale-free in the concordance cosmological model. Notably, because of their low mass, most of their interactions will be with dark satellites. Aims. In this paper we follow the evolution of gas-rich disky dwarf galaxies as they experience a minor merger with a dark satellite. We aim to characterize the effects of such an interaction on the dwarf’s star formation, morphology, and kinematical properties. Methods. We performed a suite of carefully set-up hydrodynamical simulations of dwarf galaxies that include dark matter, gas, and stars merging with a satellite consisting solely of dark matter. For the host system we vary the gas fraction, disk size and thickness, halo mass, and concentration, while we explore different masses, concentrations, and orbits for the satellite. Results. We find that the interactions cause strong starbursts of both short and long duration in the dwarfs. Their star formation rates increase by factors of a few to 10 or more. They are strongest for systems with extended gas disks and high gas fractions merging with a high-concentration satellite on a planar, radial orbit. In contrast to analogous simulations of Milky Way-mass galaxies, many of the systems experience strong morphological changes and become spheroidal even in the presence of significant amounts of gas. Conclusions. The simulated systems compare remarkably well with the observational properties of a large selection of irregular dwarf galaxies and blue compact dwarfs. This implies that mergers with dark satellites might well be happening but not be fully evident, and may thus play a role in the diversity of the dwarf galaxy population

Pengaruh Pendidikan Kesehatan terhadap Kepatuhan Diet pada Pasien DM Tipe 2 di Irna Non Bedah Penyakit dalam RSUP Dr.m. Djamil Padang Tahun 2014

Diabetes Mellitus is a degenerative disease that has become a health problem in the world. The prevalence of this disease is increasing in developing countries, including Indonesia. Uncontrolled blood sugar and further complications may be influenced by the patient's behavior and lifestyle. Disobedience in implementing the diet is one of the problems for Diabetic patients. One of the nursing interventions that can be used to overcome the disobedience of the diet is to provide health education on dietary management. The purpose of this study was to determine the effect of health education on dietary obedience in patients with Diabetes Mellitus in Irna Non Bedah Penyakit Dalam, Dr. M. Djamil Hospital. The type of research is a Quasi-Experimental by using One Group Pre-Post Test Design, 15 people as samples were taken by Purposive Sampling Method. Data collection was conducted on 01 February 2014 to 05th March 2014. The statistical test used is Wilcoxon signed rank test. The results show that there is an increased obedience of patients in implementing Diabetic diet (the right amount, the right type, and the right schedule) after a given health education (p = 0.002). As a conclusion, giving the&nbsp; health education about the implementation of the diet can improve dietaryobedience in patients with Diabetes Mellitus who are undergoing treatment. It is expected that the implementation of health education can be done intensively in health services in Dr. M. Djamil Hospital as anticipation of further complications due to disobedience in implementing the diet

CADIS has seen the Virgo overdensity and parts of the Monoceros and `Orphan' streams in retrospect

We reanalyze deep star counts in five CADIS fields. The data are presented as vertical density distributions of stars perpendicular to the Galactic plane. In three fields the profiles are consistent with each other, while in two fields significant overdensities of stars are found. The overdensity in one field can be associated with the Virgo overdensity which can be traced right into the disk of the Milky Way. Using this detection we estimate the mass of the Virgo overdensity and show that this is equivalent to the stellar content of a Local Group dwarf spheroidal galaxy. The overdensity in the second field is more difficult to associate with a previously known overdensity. We suggest that it is related both to the Monoceros stream and the recently discovered Orphan stream.Comment: 4 pages, 3 figures, accepted as Research Note by Astron. Astrophy

Perancangan Media Promosi Dilon Coffee & Eatery dengan Teknik Hand Lettering sebagai Upaya Mengenalkan Kepada Masyarakat

The purpose of designing a media campaign Dilon coffee &amp; eatery This is to introduce to the public. The research was conducted using qualitative research method is to conduct interviews, observation, documentation, and literature to get the data used to support the drafting of a media campaign design. Data were analyzed using multiple stages, namely data reduction, data presentation and conclusion. From the data analysis found some keywords that refer to promotional media communication strategy that will be used to achieve the target audiance ditujuh. After analysis of the data, ditemukanlah concept or keyword designing a media campaign called "casual". Description casual concept is the simplicity that can be used by anyone. The concept of "casual" aims to show that the Dilon coffee &amp; eatery is a café that has an appeal that is different from the others. The concept aims to convey casual café identity through the design of promotional media.