Extrasolar Planets in the Classroom

The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique. Following the simple analysis procedure describe we are able to determine the planetary radius to be 1.27 +/- 0.20 R_{J} which, within errors agrees with the establish value of 1.32 +/- 0.25 R_{J}.Comment: 7 pages, 2 figures, published in Physics Educatio

27 Canis Majoris in 1958-9

Espectrogramas de 27 Canis Majoris tomados en Mount Wilbon con una dispersión de 10 A/mm, muestran la presencia de lineas anchas de absorción que corresponden a una estrella de tipo ~ B4 V, superpuestas a las cuales aparecen las lineas angostas de una envoltura. El efecto de dilución se manifiesta particularmente en la intensidad de He I 3888. La estructura de la emisión en Hα sugiere la existencia de dos envolturas lo que, a su vez, sugiere la posibilidad de que estemos en presencia de un sistema binario, una de cuyas componentes, la B4 V, estaría rodeada de una atmósfera extendida.La otra envoltura sería exterior al sistema de las dos estrellas.Spectrograms of 27 Canis Majoris taken at Mount Wilson with a dispersion of about 10 A/mm show the presence of broad absorption lines which correspond to a star of spectral type about B4 7. Narrow absorption lines from an envelope appear superimposed upon the broad features, the dilution effect showing particularly in the intensity of He I 3888. The structure of the Hα emission suggests the existence of two envelopes, which, in turn, suggests that we are dealing with a binary system, one of the components of which, the B4 V star,would be surrounded by an extended atmosphere. The second envelope would be external to the system of the two stars. The paper will be published in full elsewhere.Asociación Argentina de Astronomí

Direct Observation of the Fourth Star in the Zeta Cancri System

Direct imaging of the zeta Cnc system has resolved the fourth star in the system, which is in orbit around zeta Cnc C. The presence of the fourth star has been inferred for many years from irregularities in the motion of star C, and recently from C's spectroscopic orbit. However, its mass is close to that of C, making its non-detection puzzling. Observing at wavelengths of 1.2, 1.7, and 2.2 microns with the adaptive-optics system of the CFHT, we have obtained images which very clearly reveal star D and show it to have the color of an M2 star. Its brightness is consonant with its being two M stars, which are not resolved in our observations but are likely to be in a short-period orbit, thereby accounting for the large mass and the difficulty of detection at optical wavelengths, where the magnitude difference is much larger. The positions and colors of all four stars in the system are reported and are consistent with the most recent astrometric observations.Comment: 7 pages including 3 tables, 1 figure; To appear in PAS

Homozygous disruption of P450 side-chain cleavage (CYP11A1) is associated with prematurity, complete 46,XY sex reversal, and severe adrenal failure

Disruption of the P450 side-chain cleavage cytochrome (P450scc) enzyme due to deleterious mutations of the CYP11A1 gene is thought to be incompatible with fetal survival because of impaired progesterone production by the fetoplacental unit. We present a 46, XY patient with a homozygous disruption of CYP11A1.The child was born prematurely with complete sex reversal and severe adrenal insufficiency. Laboratory data showed diminished or absent steroidogenesis in all pathways. Molecular genetic analysis of the CYP11A1 gene revealed a homozygous single nucleotide deletion leading to a premature termination at codon position 288. This mutation will delete highly conserved regions of the P450scc enzyme and thus is predicted to lead to a nonfunctional protein. Both healthy parents were heterozygous for this mutation.Our report demonstrates that severe disruption of P450scc can be compatible with survival in rare instances. Furthermore, defects in this enzyme are inherited in an autosomal-recessive fashion, and heterozygote carriers can be healthy and fertile. The possibility of P450scc-independent pathways of steroid synthesis in addition to the current concept of luteoplacental shift of progesterone synthesis in humans has to be questioned

Recent results on Sigma Scorpii

Espectrogramas de Sigma Scorpii obtenidos en mayo de 1960 en el Observatorio de Mount Wilson muestran: a) que en 1960 el efecto van Hoof es tan grande como en 1954 b) que no ha habido variación apreciable en el periodo fundamental en los últimos diez años; c) que el apartamiento sistemático de las velocidades del hidrógeno con respecto a las del OlI que se encontrara en 1951 y que sugiere la existencia de material que cae hacia la estrella, no está presente en 1960.Material on Sigma Scorpii secured at the Mount Wilson Observatory in May, 1960, shows a) that in 1960 the van Hoof effect was as strong as in 1954; b) that there has been no appreciable change in the fundamental period in the last ten years; c) that the systematic departure of the H velocities relative to those of O II, displayed by the material taken in 1954 and suggesting an inflow of matter towards the star, was absent in 1960.Asociación Argentina de Astronomí

Recent results on Sigma Scorpii

Espectrogramas de Sigma Scorpii obtenidos en mayo de 1960 en el Observatorio de Mount Wilson muestran: a) que en 1960 el efecto van Hoof es tan grande como en 1954 b) que no ha habido variación apreciable en el periodo fundamental en los últimos diez años; c) que el apartamiento sistemático de las velocidades del hidrógeno con respecto a las del OlI que se encontrara en 1951 y que sugiere la existencia de material que cae hacia la estrella, no está presente en 1960.Material on Sigma Scorpii secured at the Mount Wilson Observatory in May, 1960, shows a) that in 1960 the van Hoof effect was as strong as in 1954; b) that there has been no appreciable change in the fundamental period in the last ten years; c) that the systematic departure of the H velocities relative to those of O II, displayed by the material taken in 1954 and suggesting an inflow of matter towards the star, was absent in 1960.Asociación Argentina de Astronomí

Recent results on Sigma Scorpii

Espectrogramas de Sigma Scorpii obtenidos en mayo de 1960 en el Observatorio de Mount Wilson muestran: a) que en 1960 el efecto van Hoof es tan grande como en 1954 b) que no ha habido variación apreciable en el periodo fundamental en los últimos diez años; c) que el apartamiento sistemático de las velocidades del hidrógeno con respecto a las del OlI que se encontrara en 1951 y que sugiere la existencia de material que cae hacia la estrella, no está presente en 1960.Material on Sigma Scorpii secured at the Mount Wilson Observatory in May, 1960, shows a) that in 1960 the van Hoof effect was as strong as in 1954; b) that there has been no appreciable change in the fundamental period in the last ten years; c) that the systematic departure of the H velocities relative to those of O II, displayed by the material taken in 1954 and suggesting an inflow of matter towards the star, was absent in 1960.Asociación Argentina de Astronomí

New ground-based observational methods and instrumentation for asteroseismology

Space instrumentation like SOHO, MOST, CoRoT and Kepler has been and is being built to attain very high precision data to be used for asteroseismic analysis. Nonetheless, there is a very strong need for providing additional information, especially on mode identification. With this contribution I will review the efforts been put on new ground-based instrumentation and the methodology that can be used to achieve this aim.Comment: 6 pages. Review contribution to be published in Astrophysics and Space Science Proceedings series (ASSP), in the proceedings of "20th Stellar Pulsation Conference Series: Impact of new instrumentation and new insights in stellar pulsations", 5-9 September 2011, Granada, Spai

Microbial diversity in fecal samples depends on DNA extraction method: easyMag DNA extraction compared to QIAamp DNA stool mini kit extraction

BACKGROUND: There are challenges, when extracting bacterial DNA from specimens for molecular diagnostics, since fecal samples also contain DNA from human cells and many different substances derived from food, cell residues and medication that can inhibit downstream PCR. The purpose of the study was to evaluate two different DNA extraction methods in order to choose the most efficient method for studying intestinal bacterial diversity using Denaturing Gradient Gel Electrophoresis (DGGE). FINDINGS: In this study, a semi-automatic DNA extraction system (easyMag®, BioMérieux, Marcy I’Etoile, France) and a manual one (QIAamp DNA Stool Mini Kit, Qiagen, Hilden, Germany) were tested on stool samples collected from 3 patients with Inflammatory Bowel disease (IBD) and 5 healthy individuals. DNA extracts obtained by the QIAamp DNA Stool Mini Kit yield a higher amount of DNA compared to DNA extracts obtained by easyMag® from the same fecal samples. Furthermore, DNA extracts obtained using easyMag® seemed to contain inhibitory compounds, since in order to perform a successful PCR-analysis, the sample should be diluted at least 10 times. DGGE performed on PCR from DNA extracted by QIAamp DNA Stool Mini Kit DNA was very successful. CONCLUSION: QIAamp DNA Stool Mini Kit DNA extracts are optimal for DGGE runs and this extraction method yields a higher amount of DNA compared to easyMag®