We report an abundance analysis for the highly r-process-enhanced (r-II) star CS 29497-004, a very metal-poor giant with solar system Teff=5013K and [Fe/H]=-2.85, whose nature was initially discovered in the course of the HERES project. Our analysis is based on high signal-to-noise ratio, high-resolution (R~75000) VLT/UVES spectra and MARCS model atmospheres under the assumption of local thermodynamic equilibrium, and obtains abundance measurements for a total of 46 elements, 31 of which are neutron-capture elements. As is the case for the other ~25 r-II stars currently known, the heavy-element abundance pattern of CS 29497-004 well-matches a scaled solar system second peak r-process-element abundance pattern. We confirm our previous detection of Th, and demonstrate that this star does not exhibit an "actinide boost". Uranium is also detected (log{epsilon}(U)=-2.20+/-0.30), albeit with a large measurement error that hampers its use as a precision cosmochronometer. Combining the various elemental chronometer pairs that are available for this star, we derive a mean age of 12.2+/-3.7Gyr using the theoretical production ratios from published waiting-point approximation models. We further explore the high-entropy wind model (Farouqi et al., 2010ApJ...712.1359F) production ratios arising from different neutron richness of the ejecta (Ye), and derive an age of 13.7+/-4.4Gyr for a best-fitting Ye=0.447. The U/Th nuclei-chronometer is confirmed to be the most resilient to theoretical production ratios and yields an age of 16.5+/-6.6Gyr. Lead (Pb) is also tentatively detected in CS 29497-004, at a level compatible with a scaled solar r-process, or with the theoretical expectations for a pure r-process in this star.
We present basic observational data on the 6C** sample. This is a new sample of radio sources drawn from the 151-MHz 6C survey, which was filtered with radio criteria chosen to optimize the chances of finding radio galaxies at z>4. The filtering criteria are a steep-spectral index and a small angular size. The final sample consists of 68 sources from a region of sky covering 0.421sr. We present Very Large Array radio maps, and the results of K-band imaging and optical spectroscopy.
We use the 6C** sample to investigate the comoving space density of powerful, steep-spectrum radio sources. This sample, consisting of 68 objects, has virtually complete K-band photometry and spectroscopic redshifts for 32 per cent of the sources. In order to find its complete redshift distribution, we develop a method of redshift estimation based on the Kz diagram of the 3CRR, 6CE, 6C* and 7CRS radio galaxies. Based on this method, we derive redshift probability density functions for all the optically identified sources in the 6C** sample. Using a combination of spectroscopic and estimated redshifts, we select the most radio luminous sources in the sample. Their redshift distribution is then compared with the predictions of the radio luminosity function of Jarvis et al. (2001MNRAS.327..907J). We find that, within the uncertainties associated with the estimation method, the data are consistent with a constant comoving space density of steep-spectrum radio sources beyond z>2.5, and rule out a steep decline.
CS J=1-0 and NH(J,K)=(1,1) observations toward a large sample of H2O maser regions are reported. A total of 172 sources were observed. 107 were observed in CS and 164 in NH_3_. The main purpose of this work was to study the relationship between the parameters that characterize the high velocity H2O maser emission, which originates in very small (about 10 AU) and very dense (10^7-10^9/cm^3^) regions, and those that characterize the molecular emission coming from quiescent, more extended (0.1-1.0 pc) high density (10^4-10^5/cm^3^) regions, traced by the CS and NH_3_ emissions. The observations were carried out between 1986 and 1990 with the 37 m radio telescope at Haystack Observatory The emission of the (J,K)=(1,1) inversion transition of the NH_3_ molecule at 23.694496 GHz, and the emission of the J=1->0 rotational transition of the CS molecule at 48.990968 GHz were observed.
Direct imaging provides a steady flow of newly discovered giant planets and brown dwarf companions. These multi-object systems can provide information about the formation of low-mass companions in wide orbits and/or speculate about possible migration scenarios. The accurate classification of the companions is crucial for testing formation pathways. In this work we characterize further the recently discovered candidate for a planetary-mass companion CS Cha b and determine if it is still accreting. MUSE is a 4-laser-adaptive-optics-assisted medium-resolution integral-field spectrograph in the optical part of the spectrum. We observed the CS Cha system to obtain the first spectrum of CS Cha b. The companion is characterized by modelling both the spectrum from 6300{AA}, to 9300{AA}, and the photometry using archival data from the visible to the near-infrared. We find evidence of accretion and outflow signatures in H{alpha} and OI emission. The atmospheric models with the highest likelihood indicate an effective temperature of 3450+/-50K with a logg of 3.6+/-0.5dex. Based on evolutionary models, we find that the majority of the object is obscured. We determine the mass of the faint companion with several methods to be between 0.07 Msun and 0.71M_{sun}_ with an accretion rate of dM/dt=4x10^-11^+/-0.4x10^-11^M_{sun}_/yr. Our results show that CS Cha B is most likely a mid M-type star that is obscured by a highly inclined disk, which has led to its previous classification by broadband NIR photometry as a planetary-mass companion. This shows that it is important and necessary to observe over a broad spectral range to constrain the nature of faint companions.
We report photometric observations for comet C/2012 S1 (ISON) obtained during the time period immediately after discovery (r=6.28AU) until it moved into solar conjunction in mid-2013 June using the UH2.2m, and Gemini North 8m telescopes on Mauna Kea, the Lowell 1.8m in Flagstaff, the Calar Alto 1.2m telescope in Spain, the VYSOS-5 telescopes on Mauna Loa Hawaii and data from the CARA network. Additional pre-discovery data from the Pan STARRS1 survey extends the light curve back to 2011 September 30 (r=9.4AU). The images showed a similar tail morphology due to small micron sized particles throughout 2013. Observations at submillimeter wavelengths using the James Clerk Maxwell Telescope on 15 nights between 2013 March 9 (r=4.52AU) and June 16 (r=3.35AU) were used to search for CO and HCN rotation lines. No gas was detected, with upper limits for CO ranging between 3.5-4.5x10^27^molecules/s. Combined with published water production rate estimates we have generated ice sublimation models consistent with the photometric light curve. The inbound light curve is likely controlled by sublimation of CO_2_. At these distances water is not a strong contributor to the outgassing. We also infer that there was a long slow outburst of activity beginning in late 2011 peaking in mid-2013 January (r~5AU) at which point the activity decreased again through 2013 June. We suggest that this outburst was driven by CO injecting large water ice grains into the coma. Observations as the comet came out of solar conjunction seem to confirm our models.
The CSI 2264 project performed photometric monitoring of young NGC 2264 cluster members using the Spitzer Infrared Array Camera (IRAC; Fazio et al. 2004) and the Convection, Rotation and Planetary Transits satellite (CoRoT; Baglin et al. 2006) simultaneously. Thirteen other telescopes monitored the region at different times concurrently with (or closely in time to) the primary Spitzer and CoRoT joint campaign. The CSI 2264 project is described in detail in Cody et al. (2014).
This table contains CoRoT light curves for objects that are very likely NGC 2264 members (using the criteria described in Cody et al. 2014). There are many rows for each object, because each object has many epochs of data. There are 9 columns in this table, as follows. Columns 7, 8, and 9 (the IRAC excess flag and the light curve types) are duplications of information found in the Object Table, but are repeated here to make it easy for users to, e.g., pull out all of the light curves of a specific type.
The CSI 2264 project performed photometric monitoring of young NGC 2264 cluster members using the Spitzer Infrared Array Camera (IRAC; Fazio et al. 2004) and the Convection, Rotation and Planetary Transits satellite (CoRoT; Baglin et al. 2006) simultaneously. Thirteen other telescopes monitored the region at different times concurrently with (or closely in time to) the primary Spitzer and CoRoT joint campaign. The CSI 2264 project is described in detail in Cody et al. (2014).
The Object Table contains one line per object, and covers all of the objects in the greater NGC 2264 region, not just those that have light curves or are members.