- ID:
- ivo://CDS.VizieR/J/ApJ/753/125
- Title:
- Near-IR spectroscopy follow-up of 60 SDSS-DR7 QSOs
- Short Name:
- J/ApJ/753/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Single-epoch virial black hole (BH) mass estimators utilizing broad emission lines have been routinely applied to high-redshift quasars to estimate their BH masses. Depending on the redshift, different line estimators (H{alpha}, H{beta}, MgII{lambda}2798, CIV{lambda}1549) are often used with optical/near-infrared spectroscopy. Here, we use a homogeneous sample of 60 intermediate-redshift (z~1.5-2.2) Sloan Digital Sky Survey quasars with optical and near-infrared spectra covering CIV through H{alpha} to investigate the consistency between different single-epoch virial BH mass estimators.
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- ID:
- ivo://CDS.VizieR/V/144
- Title:
- Near-IR spectroscopy of low-mass binaries and brown dwarfs
- Short Name:
- V/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mass of a star at formation determines its subsequent evolution and demise. Low-mass stars are the most common products of star formation and their long main-sequence lifetimes cause them to accumulate over time. Star formation also produces many substellar-mass objects known as brown dwarfs, which emerge from their natal molecular clouds and continually cool as they age, pervading the Milky Way. Low-mass stars and brown dwarfs exhibit a wide range of physical characteristics and their abundance make them ideal subjects for testing formation and evolution models. I have examined a pair of pre-main sequence spectroscopic binaries and used radial velocity variations to determine orbital solutions and mass ratios. Additionally, I have employed synthetic spectra to estimate their effective temperatures and place them on theoretical Hertzsprung-Russell diagrams. From this analysis I discuss the formation and evolution of young binary systems and place bounds on absolute masses and radii. I have also studied the late-type T dwarfs revealed by the Wide-field Infrared Survey Explorer (WISE). This includes the exemplar T8 subdwarf Wolf 1130C, which has the lowest inferred metallicity in the literature and spectroscopic traits consistent with old age. Comparison to synthetic spectra implies that the dispersion in near-infrared colors of late-type T dwarfs is a result of age and/or thin sul de clouds. With the updated census of the L, T, and Y dwarfs we can now study specific brown dwarf subpopulations. Finally, I present a number of future studies that would develop our understanding of the physical qualities of T dwarf color outliers and disentangle the tracers of age and atmospheric properties. The thesis is available at: http://www.astro.ucla.edu/~gmace/thesis.html
- ID:
- ivo://CDS.VizieR/J/AJ/162/44
- Title:
- Near-IR spectrum of HIP 109427 with SCExAO/CHARIS
- Short Name:
- J/AJ/162/44
- Date:
- 14 Mar 2022 06:55:09
- Publisher:
- CDS
- Description:
- We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the Microwave Kinetic Inductance Detector Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star point spread function (PSF) subtraction yield 1.1-2.4{mu}m spectra. MEC reveals the companion in Y and J band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up Lp photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200K, and log_10_(L/L{odot})=-2.28_-0.04_^+0.04^, respectively. Relative astrometry of HIP109427B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia-Hipparcos absolute astrometry of the primary favor a semimajor axis of 6.55+3.0-0.48au, an eccentricity of 0.54_-0.15_^+0.28^, an inclination of 66.7_-14_^+8.5^degrees, and a dynamical mass of 0.280_-0.059_^+0.18^M{sun}. This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely used postprocessing methods to directly image faint companions to nearby stars near the telescope diffraction limit.
- ID:
- ivo://CDS.VizieR/J/A+A/517/A76
- Title:
- Near-IR spectrum of 2M1207b
- Short Name:
- J/A+A/517/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Direct-imaging searches for planets reveal wide orbit planets amenable to spectroscopy, and their atmospheres represent an important comparison to the irradiated atmospheres of Hot Jupiters. Using AO integral field spectroscopy of 2M1207b, the shape of the continuum emission over the J, H, and K bands from the atmosphere of this young, planetary mass companion is measured in order to compare with atmospheric and evolutionary models, and objects of similar temperature in young clusters and the field. The 2M1207b spectrum has the highest spectral resolution (R~300-1500) and largest wavelength coverage, including the first J-band spectrum, for this benchmark object. The high signal-to-noise of the data allow a clear identification of signatures of low surface gravity, and comparison with a grid of AMES-Dusty models reveals a best-fit effective temperature of Teff=1600K with a preferred surface gravity of logg=4.5. The J-band flux is depressed relative to nearly all L-type objects, and the detailed shape of the absorption features across the H-band exhibit differences from the model predictions. The possible origins of 2M1207b and its low luminosity are examined with the new data and analysis which suggest that extinction from a disk with large grains is a viable scenario and is preferred over scattering off an optically thick disk. The 2M1207b spectrum presents an important comparison for the types of features which may be present in upcoming spectra of the atmospheres of planets imaged in orbit around stellar primaries.
- ID:
- ivo://CDS.VizieR/III/196
- Title:
- Near-IR stellar spectra from 1.428 to 2.5 um
- Short Name:
- III/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This library is an EXTENDED VERSION of the library published by A.Lancon and B.Rocca-Volmerange in 1992. The catalog contains near-IR spectra of 84 stars, obtained with the Fourier Transform Spectrograph at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. The spectra cover the H and K atmospheric windows, i.e. wavelengths from 1.43 to 2.5 microns, with a typical resolving power of 500. The spectra have all been reduced again in 1996. The general procedure was as described in the original article, except that the intrinsic energy distributions of the stars used as references were assumed to be well represented by the models of Kurucz, 1993. Making extensive use of the Simbad data base, we have searched the literature on each of these stars, looking for effective temperature and extinction determinations. The new reduction improves the reliability of the continua, and reduces possible systematic differences between observing runs. The files contain the reduced spectra in FITS format, with fluxes in arbitrary units of energy per unit frequency (normalised to approximately 1 in the K band) and frequencies in cm^-1^, the natural units of Fourier Transform spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/169
- Title:
- Near-IR survey of Northern PNs
- Short Name:
- J/A+AS/104/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJ/755/90
- Title:
- [NeII] emission line observations from SgrA West
- Short Name:
- J/ApJ/755/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new observations of the [NeII] emission from the ionized gas in Sgr A West with improved resolution and sensitivity. About half of the emission comes from gas with kinematics indicating it is orbiting in a plane tipped about 25{deg} from the Galactic plane. This plane is consistent with that derived previously for the circumnuclear molecular disk and the northern arm and western arc ionized features. However, unlike most previous studies, we conclude that the ionized gas is not moving along the ionized features, but on more nearly circular paths. The observed speeds are close to, but probably somewhat less than expected for orbital motions in the potential of the central black hole and stars and have a small inward component. The spatial distribution of the emission is well fitted by a spiral pattern. We discuss possible physical explanations for the spatial distribution and kinematics of the ionized gas, and conclude that both may be best explained by a one-armed spiral density wave, which also accounts for both the observed low velocities and the inward velocity component. We suggest that a density wave may result from the precession of elliptical orbits in the potential of the black hole and stellar mass distribution.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/156
- Title:
- NEOWISE observations of NEOs: preliminary results
- Short Name:
- J/ApJ/743/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the NEOWISE portion of the Wide-field Infrared Survey Explorer (WISE) project, we have carried out a highly uniform survey of the near-Earth object (NEO) population at thermal infrared wavelengths ranging from 3 to 22um, allowing us to refine estimates of their numbers, sizes, and albedos. The NEOWISE survey detected NEOs the same way whether they were previously known or not, subject to the availability of ground-based follow-up observations, resulting in the discovery of more than 130 new NEOs. The survey's uniform sensitivity, observing cadence, and image quality have permitted extrapolation of the 428 near-Earth asteroids (NEAs) detected by NEOWISE during the fully cryogenic portion of the WISE mission to the larger population. We find that there are 981+/-19 NEAs larger than 1km and 20500+/-3000 NEAs larger than 100m. We show that the Spaceguard goal of detecting 90% of all 1km NEAs has been met, and that the cumulative size distribution is best represented by a broken power law with a slope of 1.32+/-0.14 below 1.5km. This power-law slope produces ~13200+/-1900 NEAs with D>140m. Although previous studies predict another break in the cumulative size distribution below D~50-100m, resulting in an increase in the number of NEOs in this size range and smaller, we did not detect enough objects to comment on this increase. The overall number for the NEA population between 100 and 1000m is lower than previous estimates. The numbers of near-Earth comets and potentially hazardous NEOs will be the subject of future work.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A95
- Title:
- NEP raster ROSAT X-ray/Optical catalog
- Short Name:
- J/A+A/645/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The North-Ecliptic Pole is an important region for extragalactic surveys. Deep/wide contiguous surveys are being performed by several space observatories. We analyse all ROSAT pointed and survey observations within 40deg^2^ around the NEP, restricting the field-of-view to the inner 30' radius. We obtain an X-ray catalogue of 805 sources with 0.5-2keV fluxes >2.9*10^-15^erg/cm^2^/s, a factor of three deeper than the ROSAT All-Sky Survey in this field. The sensitivity and angular resolution of our data are comparable to the eROSITA All-Sky Survey expectations. The 50% position error radius of the sample of X-ray sources is ~10". We use HEROES optical and near-infrared imaging photometry from Subaru and CFHT telescopes together with literature catalogues and a new deep and wide Spitzer survey in the field to identify X-ray sources and calculate photometric redshifts for the candidate counterparts. In particular we utilize mid-IR colours to identify AGN X-ray counterparts. Despite relatively large error circles and faint counterparts, confusion and systematic errors, we obtain a rather reliable catalogue of 766 optical counterparts, redshifts and optical classifications. We find a new population of luminous absorbed X-ray AGN at large redshifts, not recognized in previous X-ray surveys, but identified in our work due to the unique combination of survey solid angle, X-ray sensitivity and multiwavelength photometry. We also use the WISE and Spitzer photometry to identify a sample of 185 AGN selected purely through mid-IR colours, most of which are not detected by ROSAT. Their redshifts and upper limits to X-ray luminosity and X-ray-to-optical flux ratios are even higher than for the new class of X-ray selected luminous type 2 AGN (AGN2); they are probably a natural extension of this sample. This unique dataset is important as a reference sample for future deep surveys in the NEP region, in particular for eROSITA and also for Euclid and SPHEREX. We predict that most of the absorbed distant AGN should be readily picked up by eROSITA, but they require sensitive mid-IR imaging to be recognized as optical counterparts.
- ID:
- ivo://CDS.VizieR/J/AJ/159/63
- Title:
- New AO obs. of exoplanets & brown dwarf companions
- Short Name:
- J/AJ/159/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbital eccentricities of directly imaged exoplanets and brown dwarf companions provide clues about their formation and dynamical histories. We combine new high-contrast imaging observations of substellar companions obtained primarily with Keck/NIRC2 together with astrometry from the literature to test for differences in the population-level eccentricity distributions of 27 long-period giant planets and brown dwarf companions between 5 and 100au using hierarchical Bayesian modeling. Orbit fits are performed in a uniform manner for companions with short orbital arcs; this typically results in broad constraints for individual eccentricity distributions, but together as an ensemble, these systems provide valuable insight into their collective underlying orbital patterns. The shape of the eccentricity distribution function for our full sample of substellar companions is approximately flat from e=0-1. When subdivided by companion mass and mass ratio, the underlying distributions for giant planets and brown dwarfs show significant differences. Low mass ratio companions preferentially have low eccentricities, similar to the orbital properties of warm Jupiters found with radial velocities and transits. We interpret this as evidence for in situ formation on largely undisturbed orbits within massive extended disks. Brown dwarf companions exhibit a broad peak at e~0.6-0.9 with evidence for a dependence on orbital period. This closely resembles the orbital properties and period-eccentricity trends of wide (1-200au) stellar binaries, suggesting that brown dwarfs in this separation range predominantly form in a similar fashion. We also report evidence that the "eccentricity dichotomy" observed at small separations extends to planets on wide orbits: the mean eccentricity for the multi-planet system HR8799 is lower than for systems with single planets. In the future, larger samples and continued astrometric orbit monitoring will help establish whether these eccentricity distributions correlate with other parameters such as stellar host mass, multiplicity, and age.
