Search

Start Over Subject infrared astronomy
771. Near-IR interferometry of nova Vul 2007
ID:
ivo://CDS.VizieR/J/ApJ/755/158
Title:
Near-IR interferometry of nova Vul 2007
Short Name:
J/ApJ/755/158
Date:
21 Oct 2021
Publisher:
CDS
Description:
We used the Palomar Testbed Interferometer (PTI) to resolve 2.2{mu}m emission from the classical nova V458 Vul 2007 over the course of several days following its discovery on 2007 August 8.54 UT. We also obtained K-band photometric data and spectra of the nova during the early days of the outburst. We also used photometric measurements from the AAVSO database. This is a unique data set offering a three-technique approach: high-resolution imaging, spectroscopy, and photometry. Our analysis shows that the nova ejecta can be modeled as an inclined disk at low inclination, i.e., low ellipticity which is consistent with the nova being in the fireball phase at which the outflowing gas is optically thick, confirmed by the presence of strong P-Cygni Balmer lines in the spectra. The expansion velocity is {approx}1700km/s, derived from the H{alpha} line. By combining the nova's angular expansion rate measured by PTI with the expansion rate measured from spectroscopy, the inferred distance to the nova is 9.9-11.4kpc. We also used the K-band fluxes and the derived size of the emission to estimate the total mass ejected from the nova {approx}4x10^-4^M_{sun}_. The quick transition of the nova from Fe II to He/N class makes V458 Vul 2007 a hybrid nova.
772. Near-IR observations of young binaries
ID:
ivo://CDS.VizieR/J/A+A/376/982
Title:
Near-IR observations of young binaries
Short Name:
J/A+A/376/982
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using near-infrared speckle interferometry we have obtained resolved JHK-photometry for the components of 58 young binary systems.
773. Near-IR polarimetry of Galactic center sources
ID:
ivo://CDS.VizieR/J/A+A/557/A82
Title:
Near-IR polarimetry of Galactic center sources
Short Name:
J/A+A/557/A82
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared observations of the Galactic center (GC) provide a unique opportunity to study stellar and bow-shock polarization effects in a dusty environment. The goals of this work are to present new Ks- and Lp-band polarimetry on an unprecedented number of sources in the central parsec of the GC, thereby expanding our previous results in the H- and Ks-bands. We use AO-assisted Ks- and Lp-band observations, obtained at the ESO VLT. High precision photometry and the new polarimetric calibration method for NACO allow us to map the polarization in a region of 8"x25" (Ks) resp. 26"x28" (Lp). These are the first polarimetric observations of the GC in the Lp-band in 30 years, with vastly improved spatial resolution compared to previous results. This allows resolved polarimetry on bright bow-shock sources in this area for the first time at this wavelength.
774. Near IR properties of Galaxy disks
ID:
ivo://CDS.VizieR/J/ApJ/510/637
Title:
Near IR properties of Galaxy disks
Short Name:
J/ApJ/510/637
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have derived the near-infrared structural components of a sample of Seyfert and starburst (SBN) host galaxies by fitting near-infrared images with a new two-dimensional decomposition algorithm. An analysis of the fitted parameters shows that Seyfert 1 and SBN bulges resemble normal early-type bulges in structure and color, with (J-K)^c^_b_ about 0.1 mag redder than disk (J-K)^c^_d_. Seyfert 2 bulges, on the other hand, are bluer than normal, with (J-K)^c^_b_{approx}(J-K)^c^_d_. Seyfert disks (especially type 1), but not those of SBNs, are abnormally bright (in surface brightness), significantly more so than even the brightest normal disks. Seyfert disks are also compact, but similar to those in normal early-type spirals. For a given mass, Seyfert and particularly SBN galaxies are abnormally rich in neutral hydrogen, and there is strong, albeit indirect, evidence for lower mass-to-light (M/L) ratios in Seyfert and SBN disks, but normal M/L ratios in their bulges. In Seyfert and SBN galaxies, H I mass fractions and M/L ratios are anticorrelated, and we attribute the high gas mass fractions and low M/L ratios in SBNs and several Seyfert galaxies to ongoing star formation. Such abundant gas in Seyfert galaxies would be expected to inhibit bar formation, which may explain why active galaxies are not always barred.
775. Near-IR sources around IRAS 09002-4732
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.
776. Near-IR spectral atlas of OB stars
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.
777. Near-IR spectral classification of T dwarfs
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.
778. Near-IR spectral library of late-type stars
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.
779. Near-IR spectra of 7 Be stars and AG Car
ID:
ivo://CDS.VizieR/J/A+AS/121/113
Title:
Near-IR spectra of 7 Be stars and AG Car
Short Name:
J/A+AS/121/113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present and discuss {lambda} 6470-8780 spectra of 7 poorly-studied Be stars and of one Luminous Blue Variable (AG Car), and give equivalent widths and radial velocities of selected spectral lines.
780. Near-IR spectra of extremely red AGB stars
ID:
ivo://CDS.VizieR/J/MNRAS/400/1413
Title:
Near-IR spectra of extremely red AGB stars
Short Name:
J/MNRAS/400/1413
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a library of 139 near-IR spectra of cool asymptotic giant branch stars that will be useful for comparison with theoretical model atmosphere calculations and for modelling the integrated emission from intermediate-age stellar populations. The source list was selected from the 'extremely red' region of the Isaac Newton Telescope (INT) Photometric H{alpha} Survey (IPHAS) colour-colour plane that is overwhelmingly dominated by very late-type stars. The spectral library also includes a large fraction of S-type and carbon stars. We present a number of spectral classification sequences highlighting the various molecular features identified and discuss a number of rare features with uncertain identifications in the literature. With its focus on particularly cool photospheres, this catalogue serves as a companion to recent spectroscopic atlases of MK standards in the near-IR. Finally, the relationship between IPHAS (r'-i') and (r'-H{alpha}) colours and spectroscopically determined properties is discussed and a strong correlation between the (r'-H{alpha}) colour and the C/O abundance index for S-type and carbon stars is noted. This relation has the potential to separate O-rich, S-type and carbon stars in the Galaxy based on their photometry alone.