Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/PAZh/27/83
- Title:
- Nuclear activity of NGC 4151 in 1989-2000
- Short Name:
- J/PAZh/27/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broadband UBVRI observations of the nucleus of the Seyfert galaxy NGC 4151 from 1989 until 2000 at three astronomical observatories: the Crimean Station of the Sternberg astronomical institute, The Special Astronomical observatory in the Caucasus and the Maidanac observatory of the Ulugbek Astronomical institute in Uzbekistan. All data have been reduced to a single system and are given for an A=27.5" aperture.
- ID:
- ivo://CDS.VizieR/J/MNRAS/508/5176
- Title:
- NuSTAR Extragalactic Surveys, NEP Field
- Short Name:
- J/MNRAS/508/5176
- Date:
- 03 Dec 2021 13:27:09
- Publisher:
- CDS
- Description:
- We present the NuSTAR extragalactic survey of the James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-Domain Field. The survey covers a ~0.16deg^2^ area with a total exposure of 681ks acquired in a total of nine observations from three epochs. The survey sensitivities at 20% of the area are 2.39, 1.14, 2.76, 1.52, and 5.20x10^-14^erg/cm^2^/s in the 3-24, 3-8, 8-24, 8-16, and 16-24keV bands, respectively. The NEP survey is one of the most sensitive extragalactic surveys with NuSTAR so far. A total of 33 sources were detected above 95% reliability in at least one of the five bands. We present the number counts, logN-logS, measured in the hard X-ray 8-24 and 8-16keV bands, uniquely accessible by NuSTAR down to such faint fluxes. We performed source detection on the XMM-Newton and Chandra observations of the same field to search for soft X-ray counterparts of each NuSTAR detection. The soft band positions were used to identify optical and infrared associations. We present the X-ray properties (hardness ratio and luminosity) and optical-to-X-ray properties of the detected sources. The measured fraction of candidate Compton-thick (NH>=10^24^cm^-2^) active galactic nuclei, derived from the hardness ratio, is between 3% to 27%. As this survey was designed to have variability as its primary focus, we present preliminary results on multi-epoch flux variability in the 3-24keV band.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/17
- Title:
- NuSTAR Extragalactic Surveys: UDS field
- Short Name:
- J/ApJS/235/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR's ECDFS and COSMOS surveys. The survey covers a ~0.6deg^2^ area of the field for a total observing time of ~1.75Ms, to a half-area depth of ~155ks corrected for vignetting at 3-24keV, and reaching sensitivity limits at half-area in the full (3-24keV), soft (3-8keV), and hard (8-24keV) bands of 2.2x10^-14^erg/cm^2^/s, 1.0x10^-14^erg/cm^2^/s, and 2.7x10^-14^erg/cm^2^/s, respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of <z>~1.1. Through a broadband (0.5-24keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; N_H_>10^24^cm^-2^) fraction. Taking into account the uncertainties on each NH measurement, the final number of CT sources is 6.8+/-1.2. This corresponds to an observed CT fraction of 11.5%+/-2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/L3
- Title:
- NUV to NIR photometry of type IIP ASASSN-16at
- Short Name:
- J/ApJ/873/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report distinctly double-peaked H{alpha} and H{beta} emission lines in the late-time, nebular-phase spectra (>~200 days) of the otherwise normal at early phases (<~100 days) type IIP supernova ASASSN-16at (SN2016X). Such distinctly double-peaked nebular Balmer lines have never been observed for a type II SN. The nebular-phase Balmer emission is driven by the radioactive ^56^Co decay, so the observed line profile bifurcation suggests a strong bipolarity in the ^56^Ni distribution or in the line-forming region of the inner ejecta. The strongly bifurcated blueshifted and redshifted peaks are separated by ~3x10^3^km/s and are roughly symmetrically positioned with respect to the host-galaxy rest frame, implying that the inner ejecta are composed of two almost-detached blobs. The red peak progressively weakens relative to the blue peak, and disappears in the 740 days spectrum. One possible reason for the line-ratio evolution is increasing differential extinction from continuous formation of dust within the envelope, which is also supported by the near-infrared flux excess that develops after ~100 days.
- ID:
- ivo://CDS.VizieR/J/other/A+C/25.176
- Title:
- NVSS and FIRST variable sources
- Short Name:
- J/other/A+C/25.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the present study we have cross-correlated NVSS and FIRST radio catalogues having radio flux measurements at the same 1.4GHz frequency. This way we benefit from repeated observations from both catalogues, as they give more accurate positions and fluxes and more important, reveal large differences between the two measured fluxes, thus allowing to establish radio variability. As a result 79382 radio variables have been revealed, including 6301 with flux differences at 1.4GHz larger than 15mJy, 1917 with flux differences 45mJy and 260 with flux differences 200mJy. By using a special technique (Mickaelian & Sinamyan 2010 (J/MNRAS/407/681) Mickaelian+ 2011 (J/MNRAS/415/1061)), 2425 optically variable objects out of 6301 radio sources have been revealed. 2425 radio sources with both high radio and optical variability into four categories have been divided. 1206 (19%) out of 6301 radio sources have activity types from available catalogues and 619 (25.5%) out of 2425 radio sources with at the same time radio and optical variability have activity types from available catalogues. In addition, 279 radio sources out of 2425 have high variability in optical range. We have established their activity types when available. The IR fluxes and colours for the 6301 variable radio sources have been studied. Colour-colour diagrams show that most of the "unknown" sources are galaxies. The activity types for 110 (42%) out of 260 extremely high variable radio sources also have been retrieved.
- ID:
- ivo://CDS.VizieR/J/A+A/472/565
- Title:
- NW Ser and V1446 Aql uvby light curves
- Short Name:
- J/A+A/472/565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present accurate photometric time series of two Be stars: NW Ser and V1446 Aql. Both stars were observed at the Observatorio de Sierra Nevada (Granada) in July 2003 with an automatic four-channel Stroemgren photometer. We also present a preliminary theoretical study showing that the periodic variations exhibited by these stars can be due to pulsation.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/42
- Title:
- O and B type stars in W3: first results
- Short Name:
- J/ApJ/813/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from our survey of the star-forming complex W3, combining VRI photometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an R_V_ of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecular cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 H ii region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8-10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtraction for fiber spectra in regions of strong and spatially variable nebular emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/27
- Title:
- OAO/MuSCAT light curves of HAT-P-14b
- Short Name:
- J/ApJ/819/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Multicolor Simultaneous Camera for studying Atmospheres of Transiting exoplanets (MuSCAT) is an optical three-band (g'_2_-, r'_2_- and z_s,2_-band) imager that was recently developed for the 188cm telescope at Okayama Astrophysical Observatory with the aim of validating and characterizing transiting planets. In a pilot observation with MuSCAT we observed a primary transit of HAT-P-14b, a high-surface gravity (g_p_=38ms^-2^) hot Jupiter around a bright (V=10) F-type star. From a 2.9hr observation we achieved the five-minute binned photometric precisions of 0.028%, 0.022%, and 0.024% in the g'_2_, r'_2_, and z_s,2_ bands, respectively, which provided the highest-quality photometric data for this planet. Combining these results with those of previous observations, we search for variations of transit timing and duration over five years as well as variations of planet-star radius ratio (Rp/Rs) with wavelengths, but can find no considerable variation in any parameters. On the other hand, using the transit-subtracted light curves we simulate the achievable measurement error of Rp/Rs with MuSCAT for various planetary sizes, assuming three types of host stars: HAT-P-14, the nearby K-dwarf HAT-P-11, and the nearby M-dwarf GJ1214. Comparing our results with the expected atmospheric scale heights, we find that MuSCAT is capable of probing the atmospheres of planets as small as a sub-Jupiter (Rp~6R_{earth}_) around HAT-P-14 in all bands, a Neptune (~4R_{earth}_) around HAT-P-11 in all bands, and a super-Earth (~2.5R_{earth}_) around GJ1214 in r'_2_ and z_s,2_ bands. These results promise that MuSCAT will produce fruitful scientific outcomes in the K2 and TESS era.
- ID:
- ivo://CDS.VizieR/J/AJ/105/499
- Title:
- OB Associations and Spiral Structure in M33
- Short Name:
- J/AJ/105/499
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This file contains UBV photometry for the brightest stars in the southern spiral arm of M33. All stars brighter than V=21 are included in this file. For details on the observations and data reduction see reference. All the data is in ASCII format of the file. The observations where carried out on the Palomar 60in. telescope.
