Demo 5. Choques y explosiones sobre un carril

Objetivo: Demostrar la conservación del momento lineal en choques (elásticos e inelásticos) y explosiones, para distintos valores de la masa de los cuerpos involucrados

Demo 98. Péndulo electrostático

Objetivo: Detectar la presencia de cargas eléctricas con materiales sencillos

Demo 22. Ondas estacionarias en una cuerda

Objetivo: Demostrar la relación entre velocidad de propagación de una onda en una cuerda, longitud de onda, frecuencia y tensión

The mid-infrared extinction law in the darkest cores of the Pipe Nebula

Context. The properties of dust grains, in particular their size distribution, are expected to differ from the interstellar medium to the high-density regions within molecular clouds. Aims. We measure the mid-infrared extinction law produced by dense material in molecular cloud cores. Since the extinction at these wavelengths is caused by dust, the extinction law in cores should depart from that found in low-density environments if the dust grains have different properties. Methods. We use the unbiased LINES method to measure the slope of the reddening vectors in color-color diagrams. We derive the mid-infrared extinction law toward the dense cores B59 and FeSt 1-457 in the Pipe Nebula over a range of visual extinction between 10 and 50 magnitudes, using a combination of Spitzer/IRAC, and ESO NTT/VLT data. Results. The mid-infrared extinction law in both cores departs significantly from a power-law between 3.6 and 8 micron, suggesting that these cores contain dust with a considerable fraction of large dust grains. We find no evidence for a dependence of the extinction law with column density up to 50 magnitudes of visual extinction in these cores, and no evidence for a variation between our result and those for other clouds at lower column densities reported elsewhere in the literature. This suggests that either large grains are present even in low column density regions, or that the existing dust models need to be revised at mid-infrared wavelengths. We find a small but significant difference in the extinction law of the two cores, that we tentatively associate with the onset of star formation in B59.Comment: 8 pages, 6 figures. Accepted to A&

Stellar Properties for a Comprehensive Collection of Star-forming Regions in the SDSS APOGEE-2 Survey*

Artículo escrito por 28 autores.The Sloan Digital Sky Survey IV APOGEE-2 primary science goal was to observe red giant stars throughout the Galaxy to study its dynamics, morphology, and chemical evolution. The APOGEE instrument, a high-resolution 300-fiber H-band (1.55-1.71 μm) spectrograph, is also ideal to study other stellar populations in the Galaxy, among which are a number of star-forming regions and young open clusters. We present the results of the determination of six stellar properties (T eff, log g , [Fe/H], L/L ⊙, M/M ⊙, and age) for a sample that is composed of 3360 young stars, of subsolar to supersolar types, in 16 Galactic star formation and young open cluster regions. Those sources were selected by using a clustering method that removes most of the field contamination. Samples were also refined by removing targets affected by various systematic effects of the parameter determination. The final samples are presented in a comprehensive catalog that includes all six estimated parameters. This overview study also includes parameter spatial distribution maps for all regions and Hertzsprung-Russell ( log L / L ⊙ vs. T eff) diagrams. This study serves as a guide for detailed studies on individual regions and paves the way for the future studies on the global properties of stars in the pre-main-sequence phase of stellar evolution using more robust samples

Deep Near-Infrared Survey of the Pipe Nebula II: Data, Methods, and Dust Extinction Maps

We present a new set of high resolution dust extinction maps of the nearby and essentially starless Pipe Nebula molecular cloud. The maps were constructed from a concerted deep near-infrared imaging survey with the ESO-VLT, ESO-NTT, CAHA 3.5m telescopes, and 2MASS data. The new maps have a resolution three times higher than the previous extinction map of this cloud by Lombardi et al. (2006) and are able to resolve structure down to 2600 AU. We detect 244 significant extinction peaks across the cloud. These peaks have masses between 0.1 and 18.4 M_sun, diameters between 1.2 and 5.7e4 AU (0.06 and 0.28 pc), and mean densities of about 1e4 cm${^-3}$, all in good agreement with previous results. From the analysis of the Mean Surface Density of Companions we find a well defined scale near 1.4e4 AU below which we detect a significant decrease in structure of the cloud. This scale is smaller than the Jeans Length calculated from the mean density of the peaks. The surface density of peaks is not uniform but instead it displays clustering. Extinction peaks in the Pipe Nebula appear to have a spatial distribution similar to the stars in Taurus, suggesting that the spatial distribution of stars evolves directly from the primordial spatial distribution of high density material.Comment: Accepted for Publication in The Astrophysical Journal, 10/10. 49 pages, 16 figure