New photometry and spectroscopy for more than a hundred RR Lyrae stars in two fields located close to the bar of the Large Magellanic Cloud (LMC) are used to derive new accurate estimates of the average magnitude, the local reddening, the luminosity-metallicity relation, and the distance to the LMC. The average apparent luminosity of the RR Lyraes with complete V and B light curves is hV ( An estimate of the reddening within the two fields was obtained (1) from the Sturch method applied to the fundamental-mode pulsators (RRab's) with known metal abundance and (2) from the colors of the edges of the instability strip defined by the full sample of RR Lyrae variable stars. We obtained E(BÀV ) = 0.116 AE 0.017 and 0.086 AE 0.017 mag in fields A and B, respectively, with a clear-cut indication of a 0.03 mag differential reddening between the two fields. We find that reddening in field A is 0.028 mag smaller than derived by OGLE-II in the same area. On average, the new reddenings are also 0.035 mag larger than derived from Cepheids with projected distances within 2 from the centers of our fields. The new metallicities were combined with the apparent average V 0 luminosities to determine the slope of the luminositymetallicity relation for the RR Lyrae stars. The average I apparent luminosity of the clump stars derived by the present photometry is hI clump i = 18.319 AE 0.002 and 18.307 AE 0.003, in field A ( = 0.190, 6728 stars) and B ( = 0.184, 3851 stars), respectively. These values, once corrected for our new reddening estimates, lead to hIi 0 = 18.12 AE 0.06 mag and move the clump distance modulus to the LMC to 18.42 AE 0.07 and 18.45 AE 0.07 when Udalski or Popowski metallicity-I luminosity relations for the clump stars are adopted.All these values are only 1 shorter than provided by the Population I distance indicators and make it possible to reconcile the short-and long-distance scale on a common value for the distance modulus of the LMC of l LMC = 18.515 AE 0.085 mag.

We present new near-infrared spectroscopic measurements of the H region for a sample of 29 luminous high-redshift quasars. We have measured the width of H in those sources and added archival H width measurements to create a sample of 92 active galactic nuclei (AGNs) for which H width and rest-frame UV measurements of N v k1240 and C iv k1549 emission lines are available. Our sample spans 6 orders of magnitude in luminosity and includes 31 radio-loud AGNs. It also includes 10 narrow-line Seyfert 1 galaxies and one broad absorption line quasar. We find that metallicity, indicated by the N v/C iv line ratio, is primarily correlated with accretion rate, which is a function of luminosity and H line width. This may imply an intimate relation between starbursts, responsible for the metal enrichment of the nuclear gas, and AGN fueling, represented by the accretion rate. The correlation of metallicity with luminosity, or black hole (BH) mass, is weaker in contrast to recent results that were based on measurements of the width of C iv. We argue that using C iv as a proxy to H in estimating M BH might be problematic and lead to spurious BH mass and accretion rate estimates in individual sources. We discuss the potential implications of our new result in the framework of the starburst-AGN connection and theories of BH growth.

To constrain the formation history of an exoplanet, we need to know its chemical composition. With an equilibrium temperature of about 4,050 kelvin, the exoplanet KELT-9b (also known as HD 195689b) is an archetype of the class of ultrahot Jupiters that straddle the transition between stars and gas-giant exoplanets and are therefore useful for studying atmospheric chemistry. At these high temperatures, iron and several other transition metals are not sequestered in molecules or cloud particles and exist solely in their atomic forms. However, despite being the most abundant transition metal in nature, iron has not hitherto been detected directly in an exoplanet because it is highly refractory. The high temperatures of KELT-9b imply that its atmosphere is a tightly constrained chemical system that is expected to be nearly in chemical equilibrium and cloud-free, and it has been predicted that spectral lines of iron should be detectable in the visible range of wavelengths. Here we report observations of neutral and singly ionized atomic iron (Fe and Fe) and singly ionized atomic titanium (Ti) in the atmosphere of KELT-9b. We identify these species using cross-correlation analysis of high-resolution spectra obtained as the exoplanet passed in front of its host star. Similar detections of metals in other ultrahot Jupiters will provide constraints for planetary formation theories.

Abstract. Metallicities ([Fe/ (1996). The star-to-star scatter (0.29 dex) is larger than the observational errors, indicating a real spread in metal abundances. The derived metallicities cover the range −2.12 < [Fe/H] < −0.27, but there are only a few stars having [Fe/H] > −1. For the ab-type variables we compared our spectroscopic abundances with those obtained from the Fourier decomposition of the light curves. We find good agreement between the two techniques, once the systematic offset of 0.2 dex between the metallicity scales used in the two methods is taken into account. The spectroscopic metallicities were combined with the dereddened apparent magnitudes of the variables to derive the slope of the luminosity-metallicity relation for the LMC RR Lyrae stars: the resulting value is 0.214 ± 0.047 mag/dex. Finally, the 3 short period Cepheids have [Fe/H] values in the range −2.0 < [Fe/H] < −1.5. They are more metal-poor than typical LMC RR Lyrae stars, thus they are more likely to be Anomalous Cepheids rather than the short period Classical Cepheids that are often found in a number of dwarf Irregular galaxies.