CCD Strömgren photometry of young reddened clusters

The capabilities of CCD uvby photometry for the study of reddened young clusters are investigated. Observations of four fields in the direction of the clusters Basel 1, Berkeley 86, NGC 6704, and NGC 6756, with a total of 1665 stars measured in at least the y and b bands, produce new estimates for the clusters parameters. The results are compared to those from previously published studies in different photometric systems showing good agreement in the values of color excess and distance modulus, with the exception of NGC 6756, for which an essentially larger distance is found. Furthermore, the ages estimated for this cluster, Basel 1, and NGC 6704 are found to be higher than previously assumed, in particular for the last one. The presence of red giants as cluster members is suggested in Basel 1, NGC 6704, and NGC 6756.Consejería de Educacion y Ciencia Junta de Andalucí

The 2011 October Draconids Outburst. II. Meteoroid Chemical Abundances from Fireball Spectroscopy

On October 8, 2011 the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized to analyze this event. The SPanish Meteor Network (SPMN) joined this initiative and recorded the October Draconids by means of low light level CCD cameras. In addition, spectroscopic observations were carried out. Tens of multi-station meteor trails were recorded, including an extraordinarily bright October Draconid fireball (absolute mag. -10.5) that was simultaneously imaged from three SPMN meteor ob-serving stations located in Andalusia. Its spectrum was obtained, showing a clear evolution in the relative intensity of emission lines as the fireball penetrated deeper into the atmosphere. Here we focus on the analysis of this remarkable spectrum, but also discuss the atmospheric trajectory, atmospheric penetration, and orbital data computed for this bolide which was probably released during 21P/Giacobini-Zinner return to perihelion in 1907. The spectrum is discussed together with the tensile strength for the October Draconid meteoroids. The chemical profile evolution of the main rocky elements for this extremely bright bolide is compared with the elemental abundances obtained for 5 October Draconid fireballs also recorded during our spectroscopic campaign but observed only at a single station. Significant chemical heterogeneity between the small meteoroids is found as we should expect for cometary aggregates being formed by diverse dust components.Comment: Manuscript in press in Monthly Notices of the Royal Astronomical Society. Accepted for publication in MNRAS on April 28th, 2013 Manuscript Pages: 28 Tables: 5 Figures: 12. Manuscript associated: "The 2011 October Draconids outburst. I. Orbital elements, meteoroid fluxes and 21P/Giacobini-Zinner delivered mass to Earth" by Trigo-Rodriguez et al. is also in press in the same journa

OB Stars in the Solar Neighborhood I: Analysis of their Spatial Distribution

We present a newly-developed, three-dimensional spatial classification method, designed to analyze the spatial distribution of early type stars within the 1 kpc sphere around the Sun. We propose a distribution model formed by two intersecting disks -the Gould Belt (GB) and the Local Galactic Disk (LGD)- defined by their fundamental geometric parameters. Then, using a sample of about 550 stars of spectral types earlier than B6 and luminosity classes between III and V, with precise photometric distances of less than 1 kpc, we estimate for some spectral groups the parameters of our model, as well as single membership probabilities of GB and LGD stars, thus drawing a picture of the spatial distribution of young stars in the vicinity of the Sun.Comment: 28 pages including 9 Postscript figures, one of them in color. Accepted for publication in The Astronomical Journal, 30 January 200

Bright fireballs associated with the potentially hazardous asteroid 2007LQ19

We analyse here two very bright fireballs produced by the ablation in the atmosphere of two large meteoroids in 2009 and 2010. These slow-moving and deep-penetrating events were observed over Spain in the framework of our Spanish Fireball Network continuous meteor monitoring campaign. The analysis of the emission spectrum imaged for one of these fireballs has provided the first clues about the chemical nature of the progenitor meteoroids. The orbital parameters of these particles suggest a likely association with the recently identified July ρ-Herculid (JRH) meteoroid stream. In addition, considerations about the likely parent body of this stream are also made on the basis of orbital dissimilarity criteria. This orbital analysis reveals that both meteoroids and PHA 2007LQ19 exhibit a similar evolution during a time period of almost 8000 years, which suggests that either this near Earth object (NEO) is the potential parent of these particles or that this NEO and both meteoroids had a common progenitor in the past.España, Ministerio de Ciencia e Innovación YA2011-26522Junta de Andalucía P09-FQM-455

The ALHAMBRA survey: Evolution of galaxy clustering since z∼1

We study the clustering of galaxies as function of luminosity and redshift in the range 0.35< z < 1.25 using data from the Advanced Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey. The ALHAMBRA data used in this work cover 2.38 deg2 in seven independent fields, after applying a detailed angular selection mask, with accurate photometric redshifts,σz≲ 0.014(1 + z), down to IAB < 24. Given the depth of the survey, we select samples in B-band luminosity down to Lth ≃ 0.16L* at z=0.9. We measure the real-space clustering using the projected correlation function, accounting for photometric redshifts uncertainties. We infer the galaxy bias, and study its evolution with luminosity. We study the effect of sample variance, and confirm earlier results that the Cosmic Evolution Survey (COSMOS) and European Large Area ISO Survey North 1 (ELAIS-N1) fields are dominated by the presence of large structures. For the intermediate and bright samples, Lmed ≳ 0.6L*, we obtain a strong dependence of bias on luminosity, in agreement with previous results at similar redshift. We are able to extend this study to fainter luminosities, where we obtain an almost flat relation, similar to that observed at low redshift. Regarding the evolution of bias with redshift, our results suggest that the different galaxy populations studied reside in haloes covering a range in mass between log10[Mh( h-1M{bull's eye})] ≳ 11.5 for samples with Lmed = 0.3L* and log10[Mh( h-1M⊙)] ≳ 13.0 for samples with Lmed = 2L*, with typical occupation numbers in the range of 1-3 galaxies per halo.Junta de Andalucía P08-TIC-3531Ministerio de Ciencia e Innovación AYA2010-22111- C03-01 CSD2007-0006

The 2011 October Draconids outburst-II. Meteoroid chemical abundances from fireball spectroscopy

On 2011 October 8, the Earth crossed dust trails ejected from comet 21P/Giacobini-Zinner in the late 19th and early 20th Century. This gave rise to an outburst in the activity of the October Draconid meteor shower, and an international team was organized to analyse this event. The SPanish Meteor Network (SPMN) joined this initiative and recorded the October Draconids by means of low-light level CCD cameras. In addition, spectroscopic observations were carried out. Tens of multistation meteor trails were recorded, including an extraordinarily bright October Draconid fireball (absolute magnitude-10.5) that was simultaneously imaged from three SPMN meteor observing stations located in Andalusia. Its spectrum was obtained, showing a clear evolution in the relative intensity of emission lines as the fireball penetrated deeper into the atmosphere. Here, we focus on the analysis of this remarkable spectrum, but also discuss the atmospheric trajectory, atmospheric penetration and orbital data computed for this bolide which was probably released during 21P/Giacobini-Zinner return to perihelion in 1907. The spectrum is discussed together with the tensile strength for the October Draconid meteoroids. The chemical profile evolution of the main rocky elements for this extremely bright bolide is compared with the elemental abundances obtained for five October Draconid fireballs also recorded during our spectroscopic campaign but observed only at a single station. Significant chemical heterogeneity between the small meteoroids is found as we should expect for cometary aggregates being formed by diverse dust components.Ministerio de Ciencia e Innovación AYA2009-13227, AYA2009-14000-C03- 01, AYA2011-26522Junta de Andalucía P09-FQM4555CSIC 201050I04

Memberships and CM Diagrams of the Open Cluster NGC 7243

The results of astrometric and photometric investigations of the open cluster NGC 7243 are presented. Proper motions of 2165 stars with root-mean-square error of 1.1 mas/yr were obtained by means of PDS scanning of astrometric plates covering the time interval of 97 years. A total of 211 cluster members down to V=15.5 mag have been identified. V and B magnitudes have been determined for 2118 and 2110 stars respectively. Estimations of mass (348Mo < M < 522Mo), age (t=2.5x10^8 yr), distance (r=698 pc) and reddening (E(B-V)=0.24) of the cluster NGC 7243 have been made.Comment: 24 pages, 15 figures. Submitted to Astronomy and Astrophysic

Stellar physics with the ALHAMBRA photometric system

The ALHAMBRA photometric system was specifically designed to perform a tomography of the Universe in some selected areas. Although mainly designed for extragalactic purposes, its 20 contiguous, equal-width, medium-band photometric system in the optical wavelength range, shows a great capacity for stellar classification. In this contribution we propose a methodology for stellar classification and physical parameter estimation (Teff, log g, [Fe/H], and color excess E(B - V)) based on 18 independent reddening-free Q-values from the ALHAMBRA photometry. Based on the theoretical Spectral library BaSeL 2.2, and applied to 288 stars from the Next Generation spectral Library (NGSL), we discuss the reliability of the method and its dependence on the extinction law used