Lecture Notes and Essays in Astrophysics I September, 2004 Spain Editors A. Ulla and M. Manteiga Sponsored by the Spanish Ministry of Science and Technology and by the Royal Spanish Physical Society FOREWORD This volume entittled “Lecture Notes and Essays in Astrophysics” is the first of a series containing the invited reviews and lectures presented during the biannual meetings of the Astrophysics Group of the Royal Spanish Physical Society (“Real Sociedad Espa˜nola de F´ısica”; RSEF). In particular, it includes the conferences and reviews presented during the Astrophysics Symposium held in Madrid (Spain) in July, 2003, during the First Centennial of the RSEF. Our aim is to offer to the specialized public, and particularly to graduate and postgraduate astrophysics students, a number of selected comprehensive reviews on current topics presented by expert speakers (“Lecture Notes”). These are comple- mented by a set of chapters on more specific topics (“Essays”). This first volume gathers a set of lectures that we are very pleased to present. In the first one, Rafael Rebolo describes the Very Small Array (VSA) experiment and reviews the expected recent results on the angular power spectrum of the Cosmic Microwave Background that set constraints on cosmological parameters. White Dwarfs are the final remnants of low and intermediate mass stars. Their evolution is essentially a cooling process that lasts for ∼10 Gyr and allows us to obtain information about the age of the Galaxy, setting a clear lower limit on the age of the Universe. Jordi Isern and Enrique Garc´ıa-Berro describe the state of the art of the White Dwarf cooling theory and discuss the uncertainties still remaining. John Beckman and coauthors give a brief, historically based, survey of kinematic observations, essentially of rotation curves of spiral galaxies, produced as techniques have advanced and new wavelength ranges have been opened to observation, and of the Physics which can be derived. Agust´ın S´anchez Lavega and coauthors review our current understanding of the general circulation at cloud top levels in the atmospheres of the giant planets Jupiter and Saturn. The interest in these planets has grown strongly in recent years in view of their similarities with the recently discovered giant extrasolar planets. The final years of the 20th century and the initial years of the 21st century are witnessing a revolution in the construction of large telescopes. This has been possible thanks to the availability of both thin mirror technologies and growing computing power. Astronomy is clearly benefiting from this. Indeed the turn of the century has been rich with new discoveries, from the detections of Extrasolar Planets to the discovery of the the farthest galaxies ever seen or the detection of acceleration in the expansion of the Universe. Spain is leaving her imprint on the telescope making revolution and is promoting the construction of a 10 meter class telescope at the “El Roque de Los Muchachos” observatory, on the Island of La Palma, Spain. The Gran Telescopio Canarias (GTC) is currently at an advanced stage of construction, with science operation expected to start early in 2006. Jos´e Miguel Rodr´ıguez Es- pinosa introduces us to first hand technical considerations on the development and iii construction of new-generation telescopes and astronomical instrumentation. Recent results on Cool Stars, Hot Subdwarfs or Fullerenes in the Interstellar Medium, among several subjects covered, can also be found in the Essays of this book which we hope will provide an interesting insight into selected topics of modern Astrophysics. The editors are indebted to the Spanish Ministry of Science and Technology (project AYA2001-1657) and to the Royal Spanish Physical Society for finantial sup- port. Minia Manteiga and Ana Ulla President and Secretary of the Astrophysics Group Real Sociedad Espa˜nola de F´ısica iv CONTENTS Foreword iii Lecture Notes Interferometry of the Cosmic Microwave Background 1 Rafael Rebolo et al. White Dwarfs and the Age of the Universe 23 Jordi Isern and Enrique Garc´ıa-Berro Kinematic Measurements of Gas and Stars in Spiral Galaxies 43 John E. Beckman et al. Observations and Models of the General Circulation of Jupiter and Saturn 63 Agust´ın S´anchez Lavega et al. Astronomical Telescopes at the Turn of the Century 87 Jos´eMiguel Rodr´ıguez Espinosa Essays Fullerenes and Buckyonions in the Interstellar Medium 105 Susana Iglesias Groth Cool Stars: Chromospheric Activity, Rotation, Kinematic and Age 119 David Montes et al. Asteroseismology of Hot Subdwarf Stars 133 Raquel Oreiro Rey et al. Helium Cataclysmic Variables 143 Ricardo Moreno and Ana Ulla Automatic Classification of Stellar Spectra 153 Iciar Carricajo et al. v Geomagnetic Storms: Their Sources and a Model to Forecast the DST Index 165 Yolanda Cerrato et al. Detection of Energetic Particle Events with SOHO Space Observatory 177 Dolores Rodr´ıguez Fr´ıas et al. The Role of Laboratory in Astrophysics: Laboratory Experiments on Ices and Astrophysical Applications 187 Miguel Angel´ Satorre et al. On the Future of Ultraviolet (UV) Astronomy 197 Ana I. G´omez de Castro and Willem Wamsteker New Generation Near Infrared Spectrographs in 3.5 m to 10 m Class Telescopes 209 Arturo Manchado Author Index 215 Subject Index 217 Astrophysics Symposium Photos 221 vi INTERFEROMETRY OF THE COSMIC MICROWAVE BACKGROUND RAFAEL REBOLO 1,2 and the VSA consortium1,3,4 1 Instituto de Astrof´ısica de Canarias, E-38200 La Laguna, Tenerife, SPAIN 2 Consejo Superior de Investigaciones Cient´ıficas, SPAIN 3 Astrophysics Group, Cavendish Laboratory, University of Cambridge, Madingley R oad, CB3 OHE, UK 4 Jodrell Bank Observatory, University of Manchester, Macclesfield, Cheshire, SK 11 9DL, UK Abstract: We describe the Very Small Array (VSA) and review the recent results on the angular power spectrum of the Cosmic Microwave Background (CMB) obtained in the Ka-band (ν ≈ 33 GHz) with this instrument. This array has covered an ℓ- range of 150 to 1500 with a relatively high resolution in ℓ compared to previous measurements at ℓ ≥ 1000; this is achieved by using mosaiced observations in 7 regions covering a total of approximately 82 sq. degrees. Our resolution of ∆ℓ ≈ 60 between ℓ = 300 and ℓ = 1500 allows the first 3 acoustic peaks to be identified. Contamination by extragalactic radiosources brighter than 20 mJy has been taken into account by simultaneously monitoring identified sources with a high resolution interferometer. In addition, it has been performed a statistical correction for the small residual contribution from weaker sources that are below this flux limit. There is good agreement between the VSA power spectrum and that obtained by WMAP and other higher resolution experiments like ACBAR and CBI. We have set constraints on cosmological parameters using VSA data and combi- nations with other CMB data and external priors. Within the flat ΛCDM model, 2 +0.0012 the combined VSA+WMAP data without external priors gives Ωbh =0.0234−0.0014, 2 +0.014 +0.09 +0.06 10 +7 +0.14 Ωdmh = 0.111−0.016, h =0.73−0.05, nS = 0.97−0.03, 10 AS = 23−3 and τ =0.14−0.07. We also find evidence for a running spectral index of density fluctuations, nrun = −0.069 ± 0.032 at a level of more than 95% confidence. However, inclusion of prior information from the 2dF galaxy redshift survey reduces the significance of the result. When a general cosmological model with 12 parameters is considered we find consis- tency with other analyses available in the literature. The evidence for nrun < 0 is only marginal within this model. The fraction of dark matter in neutrinos is constrained to fν < 0.087 (95% confidence limit) which implies that mν < 0.32 eV if all the three neutrino species have the same mass. 1 Rafael Rebolo et al. Interferometry of the Cosmic Microwave Background 1 Introduction The CMB is a relic of the primitive Universe observed today as a largely isotropic ra- diation with Planckian spectral energy distribution of temperature T0=2.726±0.004 K (95 % C.L.) [1]. It carries the imprint of the primordial density fluctuations that originated the large scale structure of the Universe providing extremely valuable in- formation on the physical conditions of the very hot and dense early Universe. Peaks in the CMB angular power spectrum are a consequence of the evolution of pressure waves in the primordial plasma before the recombination epoch [2, 3]. These peaks provide information about the primordial density fluctuations, geometry, matter and radiation content and ionization history of the Universe. Their amplitudes and posi- tions are sensitive to many of the most important cosmological parameters. Following the detection of large angular scale fluctuations in the CMB temper- ature distribution by the Differential Microwave Radiometer on board the Cosmic Background Explorer (COBE) satellite [4], a major effort has been devoted to mea- sure the angular power spectrum of primordial anisotropies. Several experiments have consistently detected acoustic peaks in the power spectrum in the ℓ-range 100 − 1000 [5, 6, 7, 8, 9, 10] and a fall-off in power at high-ℓ from the damping tail [11, 12, 13]. The Wilkinson Microwave Anisotropy Probe, henceforth WMAP , has provided the highest sensitivity measurements [14, 15] over the ℓ-range 2−700. The resulting power spectrum is cosmic variance limited up to ℓ = 350 and delineates the first 2 peaks (at ℓ ∼ 220 and 550) with excellent signal-to-noise. These recent CMB measurements have brought impressive detailed cosmological information on a wide range of param- eters [16], but WMAP is limited in angular resolution and hence has not measured the power spectrum above ℓ ∼ 800 with good signal-to-noise. Additional observations at high angular resolution (angular scales and multipoles are related according to the 120◦ expression θ ∼ ℓ ) are still required to break some of the degeneracies inherent in the CMB power spectrum.