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1111. High proper motion stars in SA 94
ID:
ivo://CDS.VizieR/J/MNRAS/318/1206
Title:
High proper motion stars in SA 94
Short Name:
J/MNRAS/318/1206
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have applied the astrometric techniques devised by Murray (1986MNRAS.223..649M) for analysis of 48-inch Schmidt photographic data to SuperCOSMOS scans of UK Schmidt plates centred on Kapteyn's Selected Area 94 (RA=2h53m, DE=0{deg}). In this preliminary study, we combine astrometric data from four short-exposure V-band plates, taken in 1987 August (2 plates) and 1993 August (2 plates), with BVRI photometry from sky-limited plate material, to identify stars with proper motions exceeding 0.1"/yr. This paper discusses the completeness of the resulting sample and presents spectroscopy of 30 stars with {mu}>0.2"/yr. Based on the latter observations and the distribution in the [H_V_, (V-I)] reduced proper-motion diagram, we have classified stars in the complete sample as candidate white dwarfs, main-sequence dwarfs and halo subdwarfs, and derived estimates of the disc and halo luminosity functions.
1112. High redshift cosmic web with quasar systems
ID:
ivo://CDS.VizieR/J/A+A/568/A46
Title:
High redshift cosmic web with quasar systems
Short Name:
J/A+A/568/A46
Date:
21 Oct 2021
Publisher:
CDS
Description:
To understand the formation, evolution, and present-day properties of the cosmic web we need to study it at low and high redshifts. We trace the cosmic web at redshifts 1.0<z<1.8 using the quasar (QSO) data from in the SDSS DR7 QSO catalogue. We apply a friend-of-friend (FoF) algorithm to the quasar and random catalogues to determine systems at a series of linking length, and analyse richness and sizes of these systems. At the linking lengths l<=30Mpc/h, the number of quasar systems is larger than the number of systems detected in random catalogues, and the systems themselves have smaller diameters than random systems. The diameters of quasar systems are comparable to the sizes of poor galaxy superclusters in the local Universe. The richest quasar systems have four members. The mean space density of quasar systems is close to the mean space density of local rich superclusters. At intermediate linking lengths (40<=l<=70Mpc/h), the richness and length of quasar systems are similar to those derived from random catalogues. Quasar system diameters are similar to the sizes of rich superclusters and supercluster chains in the local Universe. The percolating system, which penetrate the whole sample volume appears in a quasar sample at a smaller linking length than in random samples (85Mpc/h). At the linking length 70Mpc/h, the richest systems of quasars have diameters exceeding 500Mpc. Quasar luminosities in systems are not correlated with the system richness. Quasar system catalogues in our web pages and at the Strasbourg Astronomical Data Center (CDS) serve as a database for searching for superclusters of galaxies and for tracing the cosmic web at high redshifts.
1113. 9 high-redshift ESSENCE supernovae
ID:
ivo://CDS.VizieR/J/AJ/130/2453
Title:
9 high-redshift ESSENCE supernovae
Short Name:
J/AJ/130/2453
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present broadband light curves of nine supernovae ranging in redshift from 0.5 to 0.8. The supernovae were discovered as part of the ESSENCE project, and the light curves are a combination of Cerro Tololo 4m and Hubble Space Telescope (HST) photometry. On the basis of spectra and/or light-curve fitting, eight of these objects are definitely Type Ia supernovae, while the classification of one is problematic. The ESSENCE project is a 5yr endeavor to discover about 200 high-redshift Type Ia supernovae, with the goal of tightly constraining the time average of the equation-of-state parameter [w=p/({rho}c^2^)] of the "dark energy." To help minimize our systematic errors, all of our ground-based photometry is obtained with the same telescope and instrument. In 2003 the highest redshift subset of ESSENCE supernovae was selected for detailed study with HST. Here we present the first photometric results of the survey.
1114. High-redshift QSOs in the SWIRE survey
ID:
ivo://CDS.VizieR/J/ApJ/675/49
Title:
High-redshift QSOs in the SWIRE survey
Short Name:
J/ApJ/675/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use a simple optical/infrared (IR) photometric selection of high-redshift QSOs that identifies a Lyman break in the optical photometry and requires a red IR color to distinguish QSOs from common interlopers. The search yields 100 z~3 (U-dropout) QSO candidates with 19<r'<22 over 11.7deg^2^ in the ELAIS-N1 (EN1) and ELAIS-N2 (EN2) fields of the Spitzer Wide-area Infrared Extragalactic (SWIRE) Legacy Survey. The z~3 selection is reliable, with spectroscopic follow-up of 10 candidates confirming that they are all QSOs at 2.83<z<3.44. We find that our z~4 (g'-dropout) sample suffers from both unreliability and incompleteness but present seven previously unidentified QSOs at 3.50<z<3.89.
1115. High-res. MIKE obs. of metal-poor stars
ID:
ivo://CDS.VizieR/J/ApJ/898/150
Title:
High-res. MIKE obs. of metal-poor stars
Short Name:
J/ApJ/898/150
Date:
21 Mar 2022 08:50:22
Publisher:
CDS
Description:
Extensive progress has recently been made in our understanding of heavy-element production via the r-process in the universe, specifically with the first observed neutron star binary merger (NSBM) event associated with the gravitational-wave signal detected by LIGO, GW170817. The chemical abundance patterns of metal-poor r-process-enhanced stars provide key evidence for the dominant site(s) of the r-process and whether NSBMs are sufficiently frequent or prolific r-process sources to be responsible for the majority of r-process material in the universe. We present atmospheric stellar parameters (using a nonlocal thermodynamic equilibrium analysis) and abundances from a detailed analysis of 141 metal-poor stars carried out as part of the R-Process Alliance (RPA) effort. We obtained high-resolution "snapshot" spectroscopy of the stars using the MIKE spectrograph on the 6.5m Magellan Clay telescope at Las Campanas Observatory in Chile. We find 10 new highly enhanced r-II (with [Eu/Fe]>+1.0), 62 new moderately enhanced r-I (+0.3<[Eu/Fe]<~+1.0), and 17 new limited-r ([Eu/Fe]<+0.3) stars. Among those, we find 17 new carbon-enhanced metal-poor (CEMP) stars, of which five are CEMP-no. We also identify one new s-process-enhanced ([Ba/Eu]>+0.5) and five new r/s (0.0<[Ba/Eu]<+0.5) stars. In the process, we discover a new ultra-metal-poor (UMP) star at [Fe/H]=-4.02. One of the r-II stars shows a deficit in {alpha} and Fe-peak elements, typical of dwarf galaxy stars. Our search for r-process-enhanced stars by RPA efforts has already roughly doubled the known r-process sample.
1116. High resolution NIR observations of z>~1 galaxies
ID:
ivo://CDS.VizieR/J/ApJ/864/8
Title:
High resolution NIR observations of z>~1 galaxies
Short Name:
J/ApJ/864/8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present images taken using the Gemini South Adaptive Optics Imager (GSAOI) with the Gemini Multi-conjugate Adaptive Optics System (GeMS) in three 2arcmin^2^ fields in the Spitzer Extragalactic Representative Volume Survey. These GeMS/GSAOI observations are among the first ~0.1" resolution data in the near-infrared spanning extragalactic fields exceeding 1.5' in size. We use these data to estimate galaxy sizes, obtaining results similar to those from studies with the Hubble Space Telescope, though we find a higher fraction of compact star-forming galaxies at z>2. To disentangle the star-forming galaxies from active galactic nuclei (AGNs), we use multiwavelength data from surveys in the optical and infrared, including far-infrared data from Herschel, as well as new radio continuum data from the Australia Telescope Compact Array and Very Large Array. We identify ultraluminous infrared galaxies (ULIRGs) at z~1-3, which consist of a combination of pure starburst galaxies and AGN/starburst composites. The ULIRGs show signs of recent merger activity, such as highly disturbed morphologies and include a rare candidate triple-AGN. We find that AGNs tend to reside in hosts with smaller scale sizes than purely star-forming galaxies of similar infrared luminosity. Our observations demonstrate the potential for MCAO to complement the deeper galaxy surveys to be made with the James Webb Space Telescope.
1117. High resolution spectra of 3 NGC104 member stars
ID:
ivo://CDS.VizieR/J/ApJ/816/70
Title:
High resolution spectra of 3 NGC104 member stars
Short Name:
J/ApJ/816/70
Date:
21 Oct 2021
Publisher:
CDS
Description:
Globular clusters are known to host peculiar objects named blue straggler stars (BSSs), significantly heavier than the normal stellar population. While these stars can be easily identified during their core hydrogen-burning phase, they are photometrically indistinguishable from their low-mass sisters in advanced stages of the subsequent evolution. A clear-cut identification of these objects would require the direct measurement of the stellar mass. We used the detailed comparison between chemical abundances derived from neutral and from ionized spectral lines as a powerful stellar "weighing device" to measure stellar mass and to identify an evolved BSS in 47Tucanae. In particular, high-resolution spectra of three bright stars, located slightly above the level of the "canonical" horizontal branch (HB) sequence in the color-magnitude diagram of 47 Tucanae, have been obtained with the UVES spectrograph. The measurements of iron and titanium abundances performed separately from neutral and ionized lines reveal that two targets have stellar parameters fully consistent with those expected for low-mass post-HB objects, while for the other target the elemental ionization balance is obtained only by assuming a mass of ~1.4M_{sun}_, which is significantly larger than the main sequence turn-off mass of the cluster (~0.85M_{sun}_). The comparison with theoretical stellar tracks suggests that this is a BSS descendant possibly experiencing its core helium-burning phase. The large applicability of the proposed method to most of the globular clusters in our Galaxy opens the possibility to initiate systematic searches for evolved BSSs, thus giving access to still unexplored phases of their evolution.
1118. High-resolution spectra of 9 RGB stars in NGC6681
ID:
ivo://CDS.VizieR/J/ApJ/846/23
Title:
High-resolution spectra of 9 RGB stars in NGC6681
Short Name:
J/ApJ/846/23
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtain high-resolution spectra of nine red giant branch stars in NGC 6681 and perform the first detailed abundance analysis of stars in this cluster. We confirm cluster membership for these stars based on consistent radial velocities of 214.5+/-3.7km/s and find a mean [Fe/H]=-1.63+/-0.07dex and [{alpha}/Fe]=0.42+/-0.11dex. Additionally, we confirm the existence of a Na-O anti-correlation in NGC 6681 and identify two populations of stars with unique abundance trends. With the use of HST photometry from Sarajedini+ (2007AJ....133.1658S) and Piotto+ (2015AJ....149...91P) we are able to identify these two populations as discrete sequences in the cluster CMD. Although we cannot confirm the nature of the polluter stars responsible for the abundance differences in these populations, these results do help put constraints on possible polluter candidates.
1119. High-resolution spectroscopy of TESS stars
ID:
ivo://CDS.VizieR/J/ApJS/248/19
Title:
High-resolution spectroscopy of TESS stars
Short Name:
J/ApJS/248/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate atmospheric parameters and chemical composition of stars play a vital role in characterizing physical parameters of exoplanetary systems and understanding of their formation. A full asteroseismic characterization of a star is also possible if its main atmospheric parameters are known. The NASA Transiting Exoplanet Survey Satellite (TESS) space telescope will play a very important role in searching of exoplanets around bright stars and stellar asteroseismic variability research. We have observed all 302 bright (V<8mag) and cooler than F5 spectral class stars in the northern TESS continuous viewing zone with a 1.65m telescope at the Moletai Astronomical Observatory of Vilnius University and the high-resolution Vilnius University Echelle Spectrograph. We uniformly determined the main atmospheric parameters, ages, orbital parameters, velocity components, and precise abundances of 24 chemical species (C(C2), N(CN), [OI], NaI, MgI, AlI, SiI, SiII, CaI, CaII, ScI, ScII, TiI, TiII, VI, CrI, CrII, MnI, FeI, FeII, CoI, NiI, CuI, and ZnI) for 277 slowly rotating single stars in the field. About 83% of the sample stars exhibit the Mg/Si ratios greater than 1.0 and may potentially harbor rocky planets in their systems.
1120. High-res. spectroscopy of LAMOST Li-rich giants
ID:
ivo://CDS.VizieR/J/ApJ/877/104
Title:
High-res. spectroscopy of LAMOST Li-rich giants
Short Name:
J/ApJ/877/104
Date:
21 Oct 2021
Publisher:
CDS
Description:
The discovery of Li-rich giants has introduced a new challenge for standard stellar evolution models. To resolve this issue, the number of this type of object has been rapidly increased through the development of worldwide surveys. Taking advantage of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey, 44 new Li-rich giants are reported, which are confirmed with high-resolution observations. Based on the high-resolution and high signal-to-noise spectra, we derived the atmospheric parameters and elemental abundances with the spectral synthesis method. We performed a detailed analysis of their evolutionary stages, infrared excess, projected rotational velocity (vsini), and stellar population. We find that (1) the Li-rich giants concentrate at the evolutionary status of the red giant branch bump, red clump, and asymptotic giant branch; (2) three of them are fast rotators and none exhibit infrared excess. Our results imply that the origins of Li enrichment are most likely to be associated with the extra mixing in the stellar interior, and the external sources might only make a minor contribution. Moreover, various Li-rich episodes take place at different evolutionary stages.