- ID:
- ivo://CDS.VizieR/J/ApJ/871/215
- Title:
- JVLA rotation measures of Smith cloud bckg sources
- Short Name:
- J/ApJ/871/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Smith Cloud is a high-velocity cloud with an orbit suggesting it has made at least one passage through the Milky Way disk. A magnetic field found around this cloud has been thought to provide extra stability as it passes through the Galactic halo. We use the Karl G. Jansky Very Large Array to measure Faraday rotation measures (RMs) toward 1105 extragalactic background point sources behind and next to the Smith Cloud to constrain the detailed geometry and strength of its magnetic field. The RM pattern across the cloud gives the detailed morphology of the magnetic field structure, which indicates a field draped over the ionized gas and compressed at the head of the cloud. We constrain the peak line-of-sight magnetic field strength to >~+5{mu}G and create a model of the magnetic field to demonstrate that a draped configuration can qualitatively explain the morphology of the observed RMs.
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- ID:
- ivo://CDS.VizieR/J/A+AS/98/393
- Title:
- 1Jy BL Lac Objects: Observational Data
- Short Name:
- J/A+AS/98/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Direct imaging and spectroscopic data are reported for the complete sample of 34 BL Lac objects selected from the 1Jy source catalogue (see Cat. <VIII/5>). A short description of each individual object is given along with a general discussion of the features observed in the optical spectra, the optical morphologies, and the environments of the BL Lac objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/522/113
- Title:
- 1Jy IRAS galaxies optical spectroscopy
- Short Name:
- J/ApJ/522/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper discusses the optical spectroscopic properties of the IRAS 1Jy sample (f_60_>1Jy) of ultraluminous infrared galaxies (ULIGs: L_IR_>10^12^L_{sun}; H_0_=75km/s/Mpc and q_0_=0). One hundred eight of the 118 1Jy ULIGs have been observed at {Delta}{lambda}=8.3{AA} resolution over the wavelength range ~4500-8900{AA}. These data are combined with large, previously published sets of optical spectroscopic data of lower luminosity infrared galaxies to look for systematic trends with infrared luminosity over the luminosity range L_IR_~10^10.5^-10^13^L_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/L9
- Title:
- 1.5Jy MOJAVE AGN sample and 3FGL data
- Short Name:
- J/ApJ/810/L9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the complete MOJAVE 1.5Jy sample of active galactic nuclei (AGNs) to examine the gamma-ray detection statistics of the brightest radio-loud blazars in the northern sky. We find that 23% of these AGNs were not detected above 0.1GeV by the Fermi-LAT during the four-year 3FGL catalog period partly because of an instrumental selection effect and partly due to their lower Doppler boosting factors. Blazars with synchrotron peaks in their spectral energy distributions located below 10^13.4^Hz also tend to have high-energy peaks that lie below the 0.1GeV threshold of the LAT, and are thus less likely to be detected by Fermi. The non-detected AGNs in the 1.5Jy sample also have significantly lower 15GHz radio modulation indices and apparent jet speeds, indicating that they have lower than average Doppler factors. Since the effective amount of relativistic Doppler boosting is enhanced in gamma-rays (particularly in the case of external inverse-Compton scattering), this makes them less likely to appear in the 3FGL catalog. Based on their observed properties, we have identified several bright radio-selected blazars that are strong candidates for future detection by Fermi.
7445. 1Jy northern AGN sample
- ID:
- ivo://CDS.VizieR/J/A+A/596/A106
- Title:
- 1Jy northern AGN sample
- Short Name:
- J/A+A/596/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at high frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A52
- Title:
- K and G dwarfs stellar granulation variability
- Short Name:
- J/A+A/597/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In solar-type stars, the attenuation of convective blueshift by stellar magnetic activity dominates the RV (radial velocity) variations over the low amplitude signal induced by low mass planets. Models of stars that differ from the Sun will require a good knowledge of the attenuation of the convective blueshift to estimate its impact on the variations. It is therefore crucial to precisely determine not only the amplitude of the convective blueshift for different types of stars, but also the dependence of this convective blueshift on magnetic activity, as these are key factors in our model producing the RV. We studied a sample of main sequence stars with spectral types from G0 to K2 and focused on their temporally averaged properties: the activity level and a criterion allowing to characterise the amplitude of the convective blueshift. This criterion is derived from the dependence of the convective blueshift with the intensity at the bottom of a large set of selected spectral lines.
7447. K and M stars photometry
- ID:
- ivo://CDS.VizieR/J/AJ/105/1962
- Title:
- K and M stars photometry
- Short Name:
- J/AJ/105/1962
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broadband UBVRI photometry is presented for 687 stars from among the dwarf K and M stars found spectroscopically by Vyssotsky [1958AJ.....63..211V]. Of these, 211 are without previous photometry.
- ID:
- ivo://nasa.heasarc/kaporixmm
- Title:
- Kappa Orionis XMM-Newton X-Ray Point Source Catalog
- Short Name:
- KAPORIXMM
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- X-rays are a powerful probe of activity in the early stages of star formation. They allow us to identify young stars even after they have lost the IR signatures of circumstellar disks and provide constraints on their distance. Here, the authors report on XMM-Newton observations that detected 121 young stellar objects (YSOs) in two fields between the filamentary dark cloud complex Lynds 1641S and the star Kappa Ori. These observations extend the Survey of Orion A with XMM and Spitzer (SOXS). The YSOs are contained in a ring of gas and dust apparent at millimeter wavelengths, and in far-IR and near-IR surveys. The X-ray luminosity function of the YSOs detected in the two fields indicates a distance of 250-280 pc, much closer than the Orion A cloud and similar to the distance estimates for Kappa Ori. The authors propose that the ring is a 5-8 pc diameter shell that has been swept up by Kappa Ori. This ring contains several groups of stars detected by Spitzer and WISE including one surrounding the Herbig Ae/Be star V1818 Ori. In this interpretation, the Kappa Ori ring is one of several shells swept up by massive stars within the Orion Eridanus Superbubble and is unrelated to the southern portion of Orion A/L 1641S. The XMM-Newton observations consist of two fields, north (Field N = KN) and south (Field S = KS), and were obtained in 2015 March 10 and 15 using EPIC as the primary instrument. Table 1 in the reference paper shows the details of the exposures, each one with a duration of about 50 ks and taken with the Medium filter. The authors used SAS version 14.0 to reduce the observation data files (ODFs) and to obtain calibrated lists of events for the MOS and pn instruments. They filtered the events in the 0.3-0.8 keV energy band and used only events with FLAG = 0 and PATTERN < 12 as prescribed by the SAS manual. With SAS, the authors obtained exposure maps in the 0.3-8.0 keV band and performed source detection with a code based on wavelet convolution that operated simultaneously on MOS and pn data. They used a threshold of significance of 4.5 sigma of the local background to discriminate real sources from spurious background fluctuations. However, they added few sources to the final list with significance S in 4.0 < S < 4.5 for the cases of positional match with objects in SIMBAD or PPMX catalogs. The final list was also checked for spurious sources that could appear at the border of the CCDs. In sum, the authors detected 238 X-ray sources with significance > 4 sigma of the local background; 104 sources are in KN and 134 in KS. The authors cross-correlated the positions of the X-ray sources with the coordinates of the IR catalog of Megeath et al. (2012, AJ, 144, 192). This IR catalog is the result of a survey of Orion with Spitzer that produced a classification of protostars and stars with disks. Of the 238 X-ray sources, 191 are identified within 8 arcseconds of one of 206 IR objects, 99 sources in KS, 92 sources in KN. Some X-ray sources were multiple matches within 8 arcsec of IR objects. For these cases, the authors assigned the most likely counterparts based on IR photometry and visual inspection of X-rays and IR images. However, nine X-ray sources were left associated with two or three IR objects. Among the IR matches, the authors found 15 stars with disks in KN and 35 in KS with X-ray detection. One protostar in KN and three in KS were detected in X-rays. The authors used X-ray detection of sources without IR excess as criteria to identify disk-less stars (hereafter Class III stars). They classified as Class III stars those IR objects with X-ray detections, with [4.5um]-[8.0um] colors < 0.3 mag and brighter than [4.5um] magnitude < 14. At the distance of the ONC (400 pc), the [4.5um] magnitude ~ 14 threshold at an age of 4-5 Myrs roughly identifies M3-M4 spectral types and masses around 0.3 solar masses. With this selection scheme, the authors identified 48 objects in KN and 19 in KS as Class III candidates. This table was created by the HEASARC in August 2016 based on the electronic version of Table 2 from the reference paper which was obtained from the CDS (their catalog J/ApJ/820/L28 file table2.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/808/103
- Title:
- Kapteyn moving group star abundances
- Short Name:
- J/ApJ/808/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kapteyn moving group has been postulated as tidal debris from {omega} Centauri. If true, members of the group should show some of the chemical abundance patterns known for stars in the cluster. We present an optical and near-infrared high-resolution, high-signal-to-noise ratio spectroscopic study of 14 stars of the Kapteyn group, plus 10 additional stars (the {omega} Cen group) that, while not listed as members of the Kapteyn group as originally defined, have nevertheless been associated dynamically with {omega} Centauri. Abundances for Na, O, Mg, Al, Ca, and Ba were derived from the optical spectra, while the strength of the chromospheric HeI10830{AA} line is studied as a possible helium abundance indicator. The resulting Na-O and Mg-Al patterns for stars of the combined Kapteyn and {omega} Cen group samples do not resemble those of {omega} Centauri, and are not different from those of field stars of the Galactic halo. The distribution of equivalent widths of the HeI10830{AA} line is consistent with that found among non-active field stars. Therefore, no evidence is found for second-generation stars within our samples, which most likely rules out a globular-cluster origin. Moreover, no hint of the unique barium overabundance at the metal-rich end, well established for {omega} Centauri stars, is seen among stars of the combined samples. Because this specific Ba pattern is present in {omega} Centauri irrespective of stellar generation, this would rule out the possibility that our entire sample might be composed of only first-generation stars from the cluster. Finally, for the stars of the Kapteyn group, the possibility of an origin in the hypothetical parent galaxy of {omega} Centauri is disfavored by the different run of {alpha}-elements with metallicity between our targets and stars from present-day dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/140/390
- Title:
- Karhunen-Loeve transform of SDSS QSOs
- Short Name:
- J/AJ/140/390
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Karhunen-Loeve (KL) transform can compactly represent the information contained in large, complex datasets, cleanly eliminating noise from the data and identifying elements of the dataset with extreme or inconsistent characteristics. We develop techniques to apply the KL transform to the 4000-5700{AA} region of 9800 QSO spectra with z<0.619 from the SDSS archive. Up to 200 eigenspectra are needed to fully reconstruct the spectra in this sample to the limit of their signal-to-noise (S/N). We propose a simple formula for selecting the optimum number of eigenspectra to use to reconstruct any given spectrum, based on the S/N of the spectrum, but validated by formal cross-validation tests.