- ID:
- ivo://CDS.VizieR/J/A+A/434/987
- Title:
- Near-IR sources around IRAS 09002-4732
- Short Name:
- J/A+A/434/987
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution near-infrared and mid-infrared imaging, mid-infrared spectroscopy and millimetre-wavelength continuum observations of the nearby massive star-forming complex IRAS 09002-4732. A rich cluster of young stars displaying near-infrared excess emission is detected. We identify the ionising source of the ultracompact H II region G268.42-0.85 and show that this star is the dominant heating and illuminating source of the region. Spectral type estimates based on different methods are consistent with a star of spectral type O9. The combination of the new observations with literature data allows us to set up the first structural model for the region.
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- ID:
- ivo://CDS.VizieR/J/ApJS/161/154
- Title:
- Near-IR spectral atlas of OB stars
- Short Name:
- J/ApJS/161/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present intermediate-resolution (R~8000-12000) high signal-to-noise (S/N) H- and K-band spectroscopy of a sample of 37 optically visible stars, ranging in spectral type from O3 to B3 and representing most luminosity classes. Spectra of this quality can be used to constrain the temperature, luminosity, and general wind properties of OB stars, when used in conjunction with sophisticated atmospheric model codes. Most important is the need for moderately high resolutions (R>=5000) and very high signal-to-noise (S/N>=150) spectra for a meaningful profile analysis. When using near-infrared spectra for a classification system, moderately high signal-to-noise (S/N~100) is still required, though the resolution can be relaxed to just a thousand or two. In the Appendix we provide a set of very high-quality near-infrared spectra of Brackett lines in six early-A dwarfs. These can be used to aid in the modeling and removal of such lines when early-A dwarfs are used for telluric spectroscopic standards.
- ID:
- ivo://CDS.VizieR/J/ApJ/637/1067
- Title:
- Near-IR spectral classification of T dwarfs
- Short Name:
- J/ApJ/637/1067
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A revised near-infrared classification scheme for T dwarfs is presented, based on and superseding prior schemes developed by Burgasser and coworkers (2002ApJ...564..421B) and Geballe and coworkers (2002ApJ...564..466G), and defined following the precepts of the MK process. Drawing from two large spectroscopic libraries of T dwarfs identified largely in the Sloan Digital Sky Survey and the Two Micron All Sky Survey, nine primary spectral standards and five alternate standards spanning spectral types T0-T8 are identified that match criteria of spectral character, brightness, absence of a resolved companion, and accessibility from both the Northern and Southern Hemispheres.
- ID:
- ivo://CDS.VizieR/J/ApJS/151/387
- Title:
- Near-IR spectral library of late-type stars
- Short Name:
- J/ApJS/151/387
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an empirical infrared spectral library of medium-resolution (R~2000-3000) H (1.6{mu}m) and K (2.2{mu}m) band spectra of 218 red stars, spanning a range of [Fe/H] from ~-2.2 to ~+0.3. The sample includes Galactic disk stars, bulge stars from Baade's window, and red giants from Galactic globular clusters. We report the values of 19 indices covering 12 spectral features measured from the spectra in the library. Finally, we derive calibrations to estimate the effective temperature, and diagnostic relationships to determine the luminosity classes of individual stars from near-infrared spectra. This paper is part of a larger effort aimed at building a near-IR spectral library to be incorporated in population synthesis models, as well as at testing synthetic stellar spectra.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1214
- Title:
- Near-IR spectroscopic survey of class I YSOs
- Short Name:
- J/AJ/140/1214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-IR spectroscopic survey of 110 Class I protostars observed from 0.80um to 2.43um at a spectroscopic resolution of R=1200. This survey is unique in its selection of targets from the whole sky, its sample size, wavelength coverage, depth, and sample selection.
- 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/A+AS/121/507
- Title:
- Near-IR surface photometry of Virgo galaxies
- Short Name:
- J/A+AS/121/507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The basic parameters of galaxies observed in this work: table 3: total H and K' magnitudes derived using circular apertures; table 5: photometric parameters derived along elliptical apertures
- 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/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.