- 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.
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Search Results
- 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.
- 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.
- 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.
- 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.
- 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.
477. 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/768/128
- Title:
- K-band calibrated visibilities of 24 Be stars
- Short Name:
- J/ApJ/768/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a high angular resolution survey of circumstellar disks around 24 northern sky Be stars. The K-band continuum survey was made using the CHARA Array long baseline interferometer (baselines of 30-331m). The interferometric visibilities were corrected for the flux contribution of stellar companions in those cases where the Be star is a member of a known binary or multiple system. For those targets with good (u, v) coverage, we used a four-parameter Gaussian elliptical disk model to fit the visibilities and to determine the axial ratio, position angle, K-band photospheric flux contribution, and angular diameter of the disk's major axis. For the other targets with relatively limited (u, v) coverage, we constrained the axial ratio, inclination angle, and/or disk position angle where necessary in order to resolve the degeneracy between possible model solutions. We also made fits of the ultraviolet and infrared spectral energy distributions (SEDs) to estimate the stellar angular diameter and infrared flux excess of each target. The mean ratio of the disk diameter (measured in K-band emission) to stellar diameter (from SED modeling) is 4.4 among the 14 cases where we reliably resolved the disk emission, a value which is generally lower than the disk size ratio measured in the higher opacity H{alpha} emission line. We estimated the equatorial rotational velocity from the projected rotational velocity and disk inclination for 12 stars, and most of these stars rotate close to or at the critical rotational velocity.
- ID:
- ivo://CDS.VizieR/J/other/PASA/26.439
- Title:
- K-band images of star-forming regions
- Short Name:
- J/other/PASA/26.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep, wide-field, Ks-band (2.14-micron) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14-micron point source catalogues (PSCs) towards each of the regions. For the regions between 10{deg}<l<350{deg} and |b|<1, we match the 2.14-micron sources with the GLIMPSE point source catalogue to generate a combined 2.14- to 8.0-micron point source catalogue. We provide this data for the astronomical community to utilise in studies of the stellar content of embedded clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/540/1016
- Title:
- K-band & NICMOS photometry of Trapezium Cluster
- Short Name:
- J/ApJ/540/1016
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained images of the Trapezium Cluster (140"x140"; 0.3pc x 0.3pc) with the Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Combining these data with new ground-based K-band spectra (R=800) and existing spectral types and photometry, we have constructed an H-R diagram and used it and other arguments to infer masses and ages.
