Collections of stellar spectra, often called stellar libraries, are useful in a variety of applications in the field of stellar populations. This is an attempt to improve the much-used Lick library of stellar spectra by removing jitter from the wavelength scale via cross-correlation, and calling the result the LickX library.
The X-ray luminosity-temperature relation for nearby T ~= 3.5-10 keV clusters is rederived using new ASCA temperatures and ROSAT luminosities. Both quantities are derived by directly excluding the cooling flow regions. This correction results in a greatly reduced scatter in the L_X_-T relation; cooling flow clusters are similar to others outside the small cooling flow regions. For a fit of the form L_bol_ {prop.to} T^{alpha}^, we obtain {alpha} = 2.64 +/- 0.27 (90%) and a residual rms scatter in log L_bol_ of 0.10. The derived relation can be directly compared to theoretical predictions that do not include radiative cooling. It also provides an accurate reference point for future evolution searches and comparison to cooler clusters. The new temperatures and L_X_-T relation together with a newly selected cluster sample are used to update the temperature function at z ~ 0.05. The resulting function is generally higher and flatter than, although within the errors of, the previous estimates by Edge and coworkers and Henry and Arnaud (as rederived by Eke and coworkers). For a qualitative estimate of constraints that the new data place on the density fluctuation spectrum, we apply the Press-Schechter formalism for {Omega}_0_ = 1 and 0.3. For {Omega}_0_ = 1, assuming cluster isothermality, the temperature function implies {sigma}_8_ = 0.55 +/- 0.03, while taking into account the observed cluster temperature profiles, {sigma}_8_ = 0.51 +/- 0.03, consistent with the previously derived range. The dependence of {sigma}_8_ on {Omega}_0_ is different from the earlier results because of our treatment of the slope of the fluctuation spectrum, n, as a free parameter. For the considered values of {Omega}_0_, n = -(2.0-2.3) +/- 0.3, somewhat steeper than that derived from the earlier temperature function data, in agreement with the local slope of the galaxy fluctuation spectrum from the Automatic Plate Measuring Facility (APM) survey, and significantly steeper than the standard cold dark matter prediction.
The Magellanic system comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), and the less frequently observed Magellanic Bridge and Magellanic Stream. The Bridge is traced by neutral gas and has an observed stellar component, while the Stream consists of gas only, with no observed stellar counterpart to date. This study uses catalogues created in the direction of the Bridge from 2MASS and WISE to investigate the stellar content of the Magellanic Bridge.
The Magellanic Catalogue of Stars (MACS) is based on scans of ESO Schmidt plates and contains about 244,000 stars covering large areas around the LMC and the SMC. The limiting magnitude is B<16.5m and the positional accuracy is better than 0.5" for 99% of the stars. The stars of this catalogue were screened interactively to ascertain that they are undisturbed by close neighbours.
The magnetic field (B-field) of the starless dark cloud L1544 has been studied using near-infrared (NIR) background starlight polarimetry (BSP) and archival data in order to characterize the properties of the plane-of-sky B-field. NIR linear polarization measurements of over 1700 stars were obtained in the H band and 201 of these were also measured in the K band. The NIR BSP properties are correlated with reddening, as traced using the Rayleigh-Jeans color excess (H-M) method, and with thermal dust emission from the L1544 cloud and envelope seen in Herschel maps. The NIR polarization position angles change at the location of the cloud and exhibit their lowest dispersion there, offering strong evidence that NIR polarization traces the plane-of-sky B-field of L1544. In this paper, the uniformity of the plane-of-sky B-field in the envelope region of L1544 is quantitatively assessed. This allows evaluation of the approach of assuming uniform field geometry when measuring relative mass-to-flux ratios in the cloud envelope and core based on averaging of the radio Zeeman observations in the envelope, as done by Crutcher et al. (2009ApJ...692..844C). In L1544, the NIR BSP shows the envelope B-field to be significantly non-uniform and likely not suitable for averaging Zeeman properties without treating intrinsic variations. Deeper analyses of the NIR BSP and related data sets, including estimates of the B-field strength and testing how it varies with position and gas density, are the subjects of later papers in this series.
The WATTS' charts provide the elevation of the limb of the moon using 1800 contour maps (step of 0.2deg) that cover all libration ranges of the moon. The contours of the maps were digitised by H.M. Nautical Almanac Office in the late 1960's, and then converted to a grid format by US Naval Observatory in the early 1970's. These charts are present in 2 forms: as an ascii file watts.dat (without carriage-return or line-feed!), or as a 3-D FITS file watts.fit (transformed from the ascii files with the program "make_fit.c"). More details, especially about the transformations between the original charts and the files stored here, and the special processing of the 36.0{deg} map (map#181), can be found in the "doc.txt" file.
We present data from a moderately deep spectroscopic Schmidt survey (B_lim_=17.5) of "active galaxies" selected by the presence of emission lines in their spectra and/or their UV excess. 92 emission line objects have been found in two adjacent fields (approximately 50deg^2^) in the direction of the southern extension of the Virgo cluster. We give a catalog containing positions, photographic R and B magnitudes, U-R colors, effective diameters, redshifts, equivalent widths and intensity ratios of the [OIII]{lambda}{lambda}4959,5007, H{beta} and [OII]{lambda}3727 emission lines. On these fields, we evaluate the completeness limit of the survey at a pseudo B magnitude values of 15.7. A more elaborate astrophysical analysis will appear in a forthcoming paper.
Between 1997 June and 2001 February the Two Micron All Sky Survey (2MASS) collected 25.4 Tbytes of raw imaging data covering 99.998% of the celestial sphere in the near-infrared J(1.25{mu}m), H(1.65{mu}m), and Ks(2.16{mu}m) bandpasses. Observations were conducted from two dedicated 1.3 m diameter telescopes located at Mount Hopkins, Arizona, and Cerro Tololo, Chile. The 2MASS All-Sky Data Release includes the FITS images covering the entire sky, a Point Source Catalog (PSC) of 471 million sources (Cat. II/242), and the present Extended Source Catalog. The 2MASS Extended Source Catalog contains sources that are extended with respect to the instantaneous PSF, such as galaxies and Galactic nebulae. The algorithms used to create the 2MASX catalog are described by Jarett et al. (2000AJ....119.2498J), and in the 2MASS Explanatory Supplement (accessible from the 2MASS Home Page). Briefly, point/ extended-source discrimination was conducted for each band-merged point-source detection by comparing a variety of radial shape, surface brightness, image moments, and symmetry parameters with characteristic stellar parameters using an oblique decision tree classifier. The classification tests included filters to exclude double and triple stars, which were one of the main contaminants in high source density regions. Stellar parameters were measured empirically as a function of time in each scan to compensate for variations in the atmospheric seeing using the aggregate properties of band-merged point-source extractions. The catalog contains 389 columns described briefly in the "Byte-by-byte Description" section below; their description includes also the 2MASS database original column names used in the original descriptions.
The mass function of supermassive black holes in our cosmic neighborhood is required to understand the statistics of their activity and consequently the origin of ultra high energy particles. We determine a mass function of supermassive black hole candidates from the entire sky except for the Galactic plane. Using the 2MASS catalogue as a starting point, and the well-established correlation between black hole mass and the bulge of old population of stars, we derive a list of nearby black hole candidates within the redshift range z<0.025, then perform an additional selection based on the Hubble type. We present our resulting catalogue elsewhere. The final list of black hole candidates above a mass of M_BH_>3x10^6^M_{sun}_ has 5829 entries. We perform a Hubble-type correction to account for selection effects, which reduces this number to 2919 black hole candidates. Here we use this catalogue to derive the black-hole mass function. We also correct for volume, so that this mass function is a volume-limited distribution to redshift 0.025. The differential mass function of nearby black hole candidates is a curved function, with a straight simple power-law of index -3 above 10^8^M_{sun}_ that becomes progressively flatter towards lower masses, turns off towards a gap below 3x10^6^M_{sun}_, and then extends into the range where nuclear star clusters replace black holes. The shape of this mass function can be explained in a simple merger picture. Integrating this mass function over the redshift range for which it has been derived, infers a total number of black holes with z<0.025, and M_BH_>10^7^M_{sun}_ of about 2.4x10^4^, or, if we average uniformly, 0.6 for every square degree on the sky.
We have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenising data from across the literature. The census contains 169 primary OB stars, including 52 O-type stars and 3 Wolf-Rayet stars. Spectral types and photometry are used to place the stars in a Hertzprung-Russell diagram, which is compared to both non-rotating and rotating stellar evolution models, from which stellar masses and ages are calculated. The star formation history and mass function of the association are assessed, and both are found to be heavily influenced by the evolution of the most massive stars to their end states. We find that the mass function of the most massive stars is consistent with a "universal" power-law slope of {Gamma}=1.3. The age distribution inferred from stellar evolutionary models with rotation and the mass function suggest the majority of star formation occurred more or less continuously between 1 and 7Myr ago, in agreement with studies of low- and intermediate mass stars in the association. We identify a nearby young pulsar and runaway O-type star that may have originated in Cyg OB2 and suggest that the association has already seen its first supernova. Finally we use the census and mass function to calculate the total mass of the association of 16500^+3800^_-2800_M_{sun}, at the low end, but consistent with, previous estimates of the total mass of Cyg OB2. Despite this Cyg OB2 is still one of the most massive groups of young stars known in our Galaxy making it a prime target for studies of star formation on the largest scales.