Search

Start Over Subject infrared astronomy
581. JHK photometry of Galactic center stars
ID:
ivo://CDS.VizieR/J/A+AS/97/587
Title:
JHK photometry of Galactic center stars
Short Name:
J/A+AS/97/587
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present K-counts and JHK detailed photometry for a number of stars with K<=+9.0 in three clear regions near the galactic centre. These regions are all located approximately at l~0.0 and at latitudes b~-3.5,-4.0 and 4.5 respectively. Their Cumulative Counts Functions (CCF's) are formed, and with the aid of an exponential disk model for the Galaxy they are separated into disk and bulge CCF. As for the case in Baade's Window (BW) (Ruelas-Mayorga & Teague, 1992A&AS...95..379R) the disk is dominant at bright magnitudes whereas the bulge dominates at the faint end of the CCF. The slope of the bulge CCF is steeper than that for the disk in all three cases corroborating the result obtained for BW. The two colour JHK diagram and the K vs J-K diagram for the three regions show that the stellar population in these areas is similar to that studied in BW by us and by Frogel & Whitford (1987ApJ...320..199F). An average value of E(J-K)~0.42mag for the reddening is obtained, which is somewhat larger than that found for BW (0.27). Finally it is shown that at K<=+9.0, the disk population may be accounted for by those sources with J-K<=+1.6 whereas the bulge population presents values for J-K in excess of +1.6.
582. JHK polarimetry of stars behind bubble N4
ID:
ivo://CDS.VizieR/J/ApJ/838/80
Title:
JHK polarimetry of stars behind bubble N4
Short Name:
J/ApJ/838/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of a curved magnetic field in the ring-like shell of the bubble N4, derived from near-infrared polarization of reddened diskless stars located behind this bubble. The magnetic field in the shell is curved and parallel to the ring-like shell, and its strength is estimated to be ~120{mu}G in the plane of the sky. The magnetic field strength in the shell is significantly enhanced compared to the local field strength. We calculate the mass-to-flux ratio for the submillimeter clumps in the shell and find that they are all magnetically subcritical. Our results demonstrate that the magnetic field strengthens as the interstellar medium is compressed into a shell, and suggest that the magnetic field has the potential to hinder star formation triggered by H II region expansion.
583. J,H,K spectroscopy of HD 106906 b
ID:
ivo://CDS.VizieR/J/A+A/608/A71
Title:
J,H,K spectroscopy of HD 106906 b
Short Name:
J/A+A/608/A71
Date:
21 Oct 2021
Publisher:
CDS
Description:
Directly imaged planets are ideal candidates for spectroscopic characterization of their atmospheres. The angular separations that are typically close to their host stars, however, reduce the achievable contrast and thus signal-to-noise ratios (S/N). We spectroscopically characterize the atmosphere of HD 106906 b, which is a young low-mass companion near the deuterium burning limit. The wide separation from its host star of 7.1" makes it an ideal candidate for high S/N and high-resolution spectroscopy. We aim to derive new constraints on the spectral type, effective temperature, and luminosity of HD 106906 b and also to provide a high S/N template spectrum for future characterization of extrasolar planets. We obtained 1.1-2.5um integral field spectroscopy with the VLT/SINFONI instrument with a spectral resolution of R~=2000-4000. New estimates of the parameters of HD 106906 b are derived by analyzing spectral features, comparing the extracted spectra to spectral catalogs of other low-mass objects, and fitting with theoretical isochrones.
584. JHKs photometry of IC 1396N
ID:
ivo://CDS.VizieR/J/A+A/504/97
Title:
JHKs photometry of IC 1396N
Short Name:
J/A+A/504/97
Date:
21 Oct 2021
Publisher:
CDS
Description:
IC 1396N is a bright-rimmed cloud associated with an intermediate-mass star-forming region, where a number of Herbig-Haro objects, H2 jet-like features, CO molecular outflows, and millimeter compact sources have been observed. We study the complex structure of the IC 1396N core and the molecular outflows detected in the region in detail and reveal the presence of additional YSOs inside this globule. We carried out a deep survey of the IC 1396N region in the J, H, K' broadband filters and deep high-angular resolution observations in the H2 narrowband filter with NICS at the TNG telescope. The completeness limits in the 2MASS standard are Ks~17.5, H~18.5, and J~19.5.
585. JHKs photometry of S269
ID:
ivo://CDS.VizieR/J/ApJ/596/1064
Title:
JHKs photometry of S269
Short Name:
J/ApJ/596/1064
Date:
21 Oct 2021
Publisher:
CDS
Description:
The star-forming region S269 is studied with deep JHKs and H_2_v=1-0S(1) images and K-band spectroscopy. The JHKs images were obtained on 2002 March 1, by using the Simultaneous-3color InfraRed Imager for Unbiased Survey of Nagoya University mounted on the InfraRed Survey Facility (IRSF) 1.4m telescope of Nagoya University at Sutherland, South African Astronomical Observatory. We obtained the broadband J, H, and K' images and narrow-band H_2_v=1-0S(1) image on 1999 November 22, using the Okayama Astrophysical System for Infrared Imaging and Spectroscopy mounted on the Okayama 1.88m telescope.
586. J-K DENIS photometry of bright southern stars
ID:
ivo://CDS.VizieR/J/A+A/413/1037
Title:
J-K DENIS photometry of bright southern stars
Short Name:
J/A+A/413/1037
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a photometric survey of bright southern stars carried out using the DENIS instrument equipped with attenuating filters. The observations were carried out not using the survey mode of DENIS, but with individual target pointings. This project was stimulated by the need to obtain near-infrared photometry of stars to be used in early commissioning observations of the ESO Very Large Telescope Interferometer, and in particular to establish a network of bright calibrator sources. We stress that near-infrared photometry is peculiarly lacking for many bright stars. These stars are saturated in 2MASS as well as in regular DENIS observations. The only other observations available for bright infrared stars are those of the Two Micron Sky Survey (<II/2>) dating from over thirty years ago. These were restricted to declinations above -30{deg} and thus cover only about half of the sky accessible from the VLTI site. We note that the final 2MASS data release includes photometry of bright stars, obtained by means of point-spread function fitting. However, this method only achieves about 30 percent accuracy, which is not sufficient for most applications. In this work, we present photometry for over 600 stars, each with at least one and up to eight measurements, in the J and K filters. Typical accuracy is at the level of 0.05mag and 0.04mag in the J and Ks bands, respectively.
587. Jovian Trojan asteroids with WISE/NEOWISE: taxonomy
ID:
ivo://CDS.VizieR/J/ApJ/759/49
Title:
Jovian Trojan asteroids with WISE/NEOWISE: taxonomy
Short Name:
J/ApJ/759/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present updated/new thermal model fits for 478 Jovian Trojan asteroids observed with the Wide-field Infrared Survey Explorer (WISE). Using the fact that the two shortest bands used by WISE, centered on 3.4 and 4.6{mu}m, are dominated by reflected light, we derive albedos of a significant fraction of these objects in these bands. While the visible albedos of both the C-, P-, and D-type asteroids are strikingly similar, the WISE data reveal that the albedo at 3.4{mu}m is different between C-/P- and D-types. The albedo at 3.4{mu}m can thus be used to classify the objects, with C-/P-types having values less than 10% and D-types have values larger than 10%. Classifying all objects larger than 50km shows that the D-type objects dominate both the leading cloud (L_4_), with a fraction of 84%, and trailing cloud (L_5_), with a fraction of 71%-80%. The two clouds thus have very similar taxonomic distribution for these large objects, but the leading cloud has a larger number of these large objects, L_4_/L_5_=1.34. The taxonomic distribution of the Jovian Trojans is found to be different from that of the large Hildas, which is dominated by C- and P-type objects. At smaller sizes, the fraction of D-type Hildas starts increasing, showing more similarities with the Jovian Trojans. If this similarity is confirmed through deeper surveys, it could hold important clues to the formation and evolution of the two populations. The Jovian Trojans does have similar taxonomic distribution to that of the Jovian irregular satellites, but lacks the ultra red surfaces found among the Saturnian irregular satellites and Centaur population.
588. Jovian Trojans asteroids with WISE/NEOWISE
ID:
ivo://CDS.VizieR/J/ApJ/742/40
Title:
Jovian Trojans asteroids with WISE/NEOWISE
Short Name:
J/ApJ/742/40
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the preliminary analysis of over 1739 known and 349 candidate Jovian Trojans observed by the NEOWISE component of the Wide-field Infrared Survey Explorer (WISE). With this survey the available diameters, albedos, and beaming parameters for the Jovian Trojans have been increased by more than an order of magnitude compared to previous surveys. We find that the Jovian Trojan population is very homogenous for sizes larger than ~10km (close to the detection limit of WISE for these objects). The observed sample consists almost exclusively of low albedo objects, having a mean albedo value of 0.07+/-0.03. The beaming parameter was also derived for a large fraction of the observed sample, and it is also very homogenous with an observed mean value of 0.88+/-0.13. Preliminary debiasing of the survey shows that our observed sample is consistent with the leading cloud containing more objects than the trailing cloud. We estimate the fraction to be N(leading)/N(trailing) ~1.4+/-0.2, lower than the 1.6+/-0.1 value derived by Szabo et al. (2007MNRAS.377.1393S).
589. Jovian-type planets around M dwarfs with MIRI/JWST
ID:
ivo://CDS.VizieR/J/AJ/159/18
Title:
Jovian-type planets around M dwarfs with MIRI/JWST
Short Name:
J/AJ/159/18
Date:
21 Oct 2021
Publisher:
CDS
Description:
The upcoming launch of the James Webb Space Telescope (JWST) will dramatically increase our understanding of exoplanets, particularly through direct imaging. Microlensing and radial velocity surveys indicate that some M dwarfs host long-period giant planets. Some of these planets will likely be just a few parsecs away and a few astronomical units from their host stars, a parameter space that cannot be probed by existing high-contrast imagers. We studied whether the coronagraphs on the Mid-infrared Instrument on JWST can detect Jovian-type planets around nearby M dwarfs. For a sample of 27 very nearby M dwarfs, we simulated a sample of Saturn-Jupiter-mass planets with three atmospheric configurations and three orbital separations, observed in three different filters. We found that the f1550c 15.5 {mu}m filter is best suited for detecting Jupiter-like planets. Jupiter-like planets with patchy cloud cover, 2 au from their star, are detectable at 15.5 {mu}m around 14 stars in our sample, while Jupiters with clearer atmospheres are detectable around all stars in the sample. Saturns were most detectable at 10.65 and 11.4 {mu}m (f1065c and f1140c filters), but only with cloud-free atmospheres and within 3 pc (six stars). Surveying all 27 stars would take <170 hr of JWST integration time, or just a few hours for a shorter survey of the most favorable targets. There is one potentially detectable known planet in our sample: GJ 832 b. Observations aimed at detecting this planet should occur in 2024-2026, when the planet is maximally separated from the star.
590. Jurassic structure
ID:
ivo://CDS.VizieR/J/A+A/644/A83
Title:
Jurassic structure
Short Name:
J/A+A/644/A83
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detailed elemental-abundance patterns of giant stars in the Galactic halo measured by the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have revealed the existence of a unique and significant stellar subpopulation of silicon-enhanced ([Si/Fe]>+0.5) metal-poor stars, spanning a wide range of metallicities (-1.5<[Fe/H]<-0.8). Stars with over-abundances in [Si/Fe] are of great interest because these have very strong silicon (^28^Si) spectral features for stars of their metallicity and evolutionary stage, offering clues about rare nucleosynthetic pathways in globular clusters (GCs). Si-rich field stars have been conjectured to have been evaporated from GCs, however, the origin of their abundances remains unclear, and several scenarios have been offered to explain the anomalous abundance ratios. These include the hypothesis that some of them were born from a cloud of gas previously polluted by a progenitor that underwent a specific and peculiar nucleosynthesis event or, alternatively, that they were due to mass transfer from a previous evolved companion. However, those scenarios do not simultaneously explain the wide gamut of chemical species that are found in Si-rich stars. Instead, we show that the present inventory of such unusual stars, as well as their relation to known halo substructures (including the in situ halo, Gaia-Enceladus, the Helmi Stream(s), and Sequoia, among others), is still incomplete. We report the chemical abundances of the iron-peak (Fe), the light- (C and N), the alpha- (O and Mg), the odd-Z (Na and Al), and the s-process (Ce and Nd) elements of 55 newly identified Si-rich field stars (among more than ~600000 APOGEE-2 targets), which exhibit over-abundances of [Si/Fe] as extreme as those observed in some Galactic GCs, and they are relatively well distinguished from other stars in the [Si/Fe]-[Fe/H] plane. This new census confirms the presence of a statistically significant and chemically-anomalous structure in the inner halo: Jurassic. The chemo-dynamical properties of the Jurassic structure is consistent with it being the tidally disrupted remains of GCs, which are easily distinguished by an over-abundance of [Si/Fe] among Milky Way (MW) populations or satellites.