Search

Start Over Subject spectroscopy
1091. HIRES radial velocities of HD9446, HD43691 & HD179079
ID:
ivo://CDS.VizieR/J/AJ/159/197
Title:
HIRES radial velocities of HD9446, HD43691 & HD179079
Short Name:
J/AJ/159/197
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Transit Ephemeris Refinement and Monitoring Survey is a project that aims to detect transits of intermediate-long period planets by refining orbital parameters of the known radial velocity planets using additional data from ground-based telescopes, calculating a revised transit ephemeris for the planet, then monitoring the planet host star during the predicted transit window. Here we present the results from three systems that had high probabilities of transiting planets: HD9446b and c, HD43691b, and HD179079b. We provide new radial velocity (RV) measurements that are then used to improve the orbital solution for the known planets. We search the RV data for indications of additional planets in orbit and find that HD9446 shows a strong linear trend of 4.8{sigma}. Using the newly refined planet orbital solutions, which include a new best-fit solution for the orbital period of HD9446c, and an improved transit ephemerides, we found no evidence of transiting planets in the photometry for each system. Transits of HD9446b can be ruled out completely and transits HD9446c and HD43691b can be ruled out for impact parameters up to b=0.5778 and b=0.898, respectively, due to gaps in the photometry. A transit of HD179079b cannot be ruled out, however, due to the relatively small size of this planet compared to the large star and thus low signal to noise. We determine properties of the three host stars through spectroscopic analysis and find through photometric analysis that HD9446 exhibits periodic variability.
1092. HIRES radial velocity follow up for Kepler-129
ID:
ivo://CDS.VizieR/J/AJ/162/89
Title:
HIRES radial velocity follow up for Kepler-129
Short Name:
J/AJ/162/89
Date:
14 Mar 2022 06:24:52
Publisher:
CDS
Description:
We present the discovery of Kepler-129d (P_d_=7.2_-0.3_^+0.4^yr, m_sini_d__=8.3_-0.7_^+1.1^M_Jup_, e_d_=0.15_-0.05_^+0.07^) based on six years of radial-velocity observations from Keck/HIRES. Kepler-129 also hosts two transiting sub-Neptunes: Kepler-129b (P_b_= 15.79days, r_b_=2.40{+/-}0.04R{Earth}) and Kepler-129c (P_c_=82.20days, r_c_=2.52{+/-}0.07R{Earth}) for which we measure masses of m_b_<20M{Earth} and m_c_=43_-12_^+13^M{Earth}. Kepler-129 is a hierarchical system consisting of two tightly packed inner planets and a massive external companion. In such a system, two inner planets precess around the orbital normal of the outer companion, causing their inclinations to oscillate with time. Based on an asteroseismic analysis of Kepler data, we find tentative evidence that Kepler-129b and c are misaligned with stellar spin axis by >~38{deg}, which could be torqued by Kepler-129 d if it is inclined by >~19{deg} relative to inner planets. Using N-body simulations, we provide additional constraints on the mutual inclination between Kepler-129d and inner planets by estimating the fraction of time during which two inner planets both transit. The probability that two planets both transit decreases as their misalignment with Kepler-129d increases. We also find a more massive Kepler-129c enables the two inner planets to become strongly coupled and more resistant to perturbations from Kepler-129d. The unusually high mass of Kepler-129c provides a valuable benchmark for both planetary dynamics and interior structure, since the best-fit mass is consistent with this 2.5R{Earth} planet having a rocky surface.
1093. HI-selected-Lyman limit system metallicities
ID:
ivo://CDS.VizieR/J/ApJ/833/270
Title:
HI-selected-Lyman limit system metallicities
Short Name:
J/ApJ/833/270
Date:
21 Oct 2021
Publisher:
CDS
Description:
We measured metallicities for 33 z=3.4-4.2 absorption line systems drawn from a sample of HI-selected-Lyman limit systems (LLSs) identified in Sloan Digital Sky Survey (SDSS) quasar spectra and stratified based on metal line features. We obtained higher-resolution spectra with the Keck Echellette Spectrograph and Imager, selecting targets according to our stratification scheme in an effort to fully sample the LLS population metallicity distribution. We established a plausible range of HI column densities and measured column densities (or limits) for ions of carbon, silicon, and aluminum, finding ionization-corrected metallicities or upper limits. Interestingly, our ionization models were better constrained with enhanced {alpha}-to-aluminum abundances, with a median abundance ratio of [{alpha}/Al]=0.3. Measured metallicities were generally low, ranging from [M/H]=-3 to -1.68, with even lower metallicities likely for some systems with upper limits. Using survival statistics to incorporate limits, we constructed the cumulative distribution function (CDF) for LLS metallicities. Recent models of galaxy evolution propose that galaxies replenish their gas from the low-metallicity intergalactic medium (IGM) via high-density HI "flows" and eject enriched interstellar gas via outflows. Thus, there has been some expectation that LLSs at the peak of cosmic star formation (z~3) might have a bimodal metallicity distribution. We modeled our CDF as a mix of two Gaussian distributions, one reflecting the metallicity of the IGM and the other representative of the interstellar medium of star-forming galaxies. This bimodal distribution yielded a poor fit. A single Gaussian distribution better represented the sample with a low mean metallicity of [M/H]~-2.5.
1094. HI-selected Lyman limit systems metallicities
ID:
ivo://CDS.VizieR/J/ApJ/833/283
Title:
HI-selected Lyman limit systems metallicities
Short Name:
J/ApJ/833/283
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results from our KODIAQ Z survey aimed at determining the metallicity distribution and physical properties of the z>~2 partial and full Lyman limit systems (pLLSs and LLSs; 16.2<=logN_HI_<19), which are probed of the interface regions between the intergalactic medium (IGM) and galaxies. We study 31 HI-selected pLLSs and LLSs at 2.3<z<3.3 observed with Keck/HIRES in absorption against background QSOs. We compare the column densities of metal ions to HI and use photoionization models to assess the metallicity. The metallicity distribution of the pLLSs/LLSs at 2.3<z<3.3 is consistent with a unimodal distribution peaking at [X/H]~-2. The metallicity distribution of these absorbers therefore evolves markedly with z since at z<~1 it is bimodal with peaks at [X/H]~-1.8 and -0.3. There is a substantial fraction (25%-41%) of pLLSs/LLSs with metallicities well below those of damped Ly{alpha} absorbers (DLAs) at any studied z from z<~1 to z~2-4, implying reservoirs of metal-poor, cool, dense gas in the IGM/galaxy interface at all z. However, the gas probed by pLLSs and LLSs is rarely pristine, with a fraction of 3%-18% for pLLSs/LLSs with [X/H]<=-3. We find C/{alpha} enhancement in several pLLSs and LLSs in the metallicity range -2<~[X/H]<~-0.5, where C/{alpha} is 2-5 times larger than observed in Galactic metal-poor stars or high-redshift DLAs at similar metallicities. This is likely caused by preferential ejection of carbon from metal-poor galaxies into their surroundings.
1095. HI spectral properties of galaxies
ID:
ivo://CDS.VizieR/VIII/77
Title:
HI spectral properties of galaxies
Short Name:
VIII/77
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a homogeneous compilation of HI spectral parameters extracted from global 21cm line spectra for some 9000 galaxies in the local universe (heliocentric velocity -200<V_{sun}_<28,000km/s) obtained with a variety of large single-dish radio telescopes but reanalyzed using a single set of parameter extraction algorithms. Corrections to the observed HI line flux for source extent and pointing offsets and to the HI line widths for instrumental broadening and smoothing are applied according to model estimates to produce a homogenous catalog of derived properties with quantitative error estimates. Where the redshift is available from optical studies, we also provide flux measurements for an additional 156 galaxies classified as marginal HI detections and rms noise limits for 494 galaxies classified as nondetections.
1096. HI spectra of extremely metal-poor (XMP) galaxies
ID:
ivo://CDS.VizieR/J/A+A/558/A18
Title:
HI spectra of extremely metal-poor (XMP) galaxies
Short Name:
J/A+A/558/A18
Date:
21 Oct 2021
Publisher:
CDS
Description:
Extremely metal-poor (XMP) galaxies are chemically, and possibly dynamically, primordial objects in the local Universe. Our objective is to characterize the HI content of the XMP galaxies as a class, using as a reference the list of 140 known local XMPs compiled by Morales-Luis et al. (2011, Cat. J/ApJ/743/77). We have observed 29 XMPs, which had not been observed before at 21 cm, using the Effelsberg radio telescope. This information was complemented with Hi data published in literature for a further 53 XMPs. In addition, optical data from the literature provided morphologies, stellar masses, star-formation rates and metallicities.
1097. HI survey of AGNs
ID:
ivo://CDS.VizieR/J/ApJS/177/103
Title:
HI survey of AGNs
Short Name:
J/ApJS/177/103
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted a new Arecibo survey for HI emission for 113 galaxies with broad-line (type 1) active galactic nuclei (AGNs) out to recession velocities as high as ~35000km/s. The primary aim of the study is to obtain sensitive HI spectra for a well-defined, uniformly selected sample of active galaxies that have estimates of their black hole masses in order to investigate correlations between HI properties and the characteristics of the AGNs. HI emission was detected in 66 out of the 101 (65%) objects with spectra uncorrupted by radio frequency interference, among which 45 (68%) have line profiles with adequate signal-to-noise ratio and sufficiently reliable inclination corrections to yield robust deprojected rotational velocities. This paper presents the basic survey products, including an atlas of HI spectra, measurements of HI flux, line width, profile asymmetry, optical images, optical spectroscopic parameters, as well as a summary of a number of derived properties pertaining to the host galaxies. To enlarge our primary sample, we also assemble all previously published HI measurements of type 1 AGNs for which we can estimate black hole masses, which total an additional 53 objects. The final comprehensive compilation of 154 broad-line active galaxies, by far the largest sample ever studied, forms the basis of our companion paper, which uses the HI database to explore a number of properties of the AGN host galaxies.
1098. HK', CN & CH chemical indexes in NGC 362 & NGC 6723
ID:
ivo://CDS.VizieR/J/ApJ/832/99
Title:
HK', CN & CH chemical indexes in NGC 362 & NGC 6723
Short Name:
J/ApJ/832/99
Date:
21 Oct 2021
Publisher:
CDS
Description:
Most globular clusters (GCs) are now known to host multiple stellar populations with different abundances of light elements. Here we use narrow-band photometry and low-resolution spectroscopy for NGC 362 and NGC 6723 to investigate their chemical properties and radial distributions of subpopulations. We confirm that NGC 362 and NGC 6723 are among the GCs with multiple populations showing bimodal CN distribution and CN-CH anticorrelation without a significant spread in calcium abundance. These two GCs show more centrally concentrated CN-weak, earlier generation stars compared to the CN-strong, later generation stars. These trends are reversed with respect to those found in previous studies for many other GCs. Our findings, therefore, seem contradictory to the current scenario for the formation of multiple stellar populations, but mass segregation acting on the two subpopulations might be a possible solution to explain this reversed radial trend.
1099. HLock01-LAB 2D spectrum
ID:
ivo://CDS.VizieR/J/A+A/629/A23
Title:
HLock01-LAB 2D spectrum
Short Name:
J/A+A/629/A23
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the discovery of HLock01-LAB, a luminous and large Ly{alpha} nebula at z=3.326. Medium-band imaging and long-slit spectroscopic observations with the Gran Telescopio Canarias reveal extended emission in the Ly{alpha} 1215{AA}, CIV 1550{AA}, and HeII 1640{AA} lines over ~100kpc, and a total luminosity L(Ly{alpha})=(6.4+/-0.1)x10^44^erg/s. HLock01-LAB presents an elongated morphology aligned with two faint radio sources contained within the central ~8kpc of the nebula. The radio structures are consistent with faint radio jets or lobes of a central galaxy, whose spectrum shows nebular emission characteristic of a type-II active galactic nucleus (AGN). The continuum emission of the AGN at short wavelengths is however likely dominated by stellar emission of the host galaxy, for which we derive a stellar mass M*~2.3x10^11^M_{sun}_. Our kinematic analysis shows that the ionized gas is perturbed almost exclusively in the inner region between the radio structures, probably as a consequence of jet-gas interactions, whereas in the outer regions the ionized gas appears more quiescent. The detection of extended emission in CIV and CIII] indicates that the gas within the nebula is not primordial. Feedback may have enriched the halo at at least 50kpc from the nuclear region. Using rest-frame UV emission-line diagnostics, we find that the gas in the nebula is likely heated by the AGN. Nevertheless, at the center of the nebula we find extreme emission line ratios of Ly{alpha}/CIV~60 and Ly{alpha}/HeII~80, one of the highest values measured to date, and well above the standard values of photoionization models (Ly{alpha}/HeII ~30 for case B photoionization). Our data suggest that jet-induced shocks are likely responsible for the increase of the electron temperature and, thus, the observed Ly{alpha} enhancement in the center of the nebula. This scenario is further supported by the presence of radio structures and perturbed kinematics in this region. The large Ly{alpha} luminosity in HLock01-LAB is likely due to a combination of AGN photoionization and jet-induced shocks, highlighting the diversity of sources of energy powering Ly{alpha} nebulae. Future follow-up observations of HLock01-LAB will help to reveal the finer details of the excitation conditions of the gas induced by jets and to investigate the underlying cooling and feedback processes in this unique object.
1100. HNCO in planetary atmospheres.
ID:
ivo://CDS.VizieR/J/A+A/616/A150
Title:
HNCO in planetary atmospheres.
Short Name:
J/A+A/616/A150
Date:
21 Oct 2021
Publisher:
CDS
Description:
Time-resolved Fourier transform infrared emission spectroscopy, Fourier transform absorption infrared spectroscopy, and high-resolution UV-ViS emission spectroscopy have been exploited in order to characterize the chemistry of isocyanic acid (HNCO) under glow discharge conditions in planetary atmospheres. HNCO mixtures (i.e., composed of di-hydrogen or ammonia) have been investigated in order to unveil the possible reaction pathways leading to the synthesis of the key prebiotic molecule formamide (HCONH_2_), upon planetary atmospheres containing isocyanic acid in presence of di-hydrogen and, separately, of ammonia. In addition, ab initio Molecular Dynamics simulations coupled with a state-of-the-art metadynamics technique have been performed in order to identify the most likely chemical pathways connecting HNCO to formamide. It turned out that the direct hydrogenation of HNCO is thermodynamically favored. Incidentally, also the experimental results - supplied by a simplified kinetic model - proved the favorability of the reaction HNCO + H_2_ -> HCONH_2_ which, moreover, spontaneously takes place in unbiased ab initio Molecular Dynamics simulations carried out under the effect of intense electric fields.

Limit your search

more »

more »

more »

more »

more »