Search

Start Over Capability Type Simple Cone Search
17521. W 40 Star-Forming Region Chandra X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/w40sfrcxo
Title:
W 40 Star-Forming Region Chandra X-Ray Point Source Catalog
Short Name:
W40SFRCXO
Date:
28 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The young stellar cluster illuminating the W40 H II region, one of the nearest massive star-forming regions (SFRs), has been observed with the ACIS detector on board the Chandra X-ray Observatory. Due to its high obscuration, this is a poorly studied stellar cluster with only a handful of bright stars visible in the optical band, including three OB stars identified as primary excitation sources. The authors detect 225 X-ray sources, of which 85% are confidently identified as young stellar members of the region. Two potential distances of the cluster, 260 pc and 600 pc, are used in the paper. Supposing the X-ray luminosity function of SFRs to be universal, it supports a 600 pc distance as a lower limit for W40 and a total population of at least 600 stars down to 0.1 M<sub>sun</sub> under the assumption of a coeval population with a uniform obscuration. In fact, there is strong spatial variation in K<sub>s</sub>-band-excess disk fraction and non-uniform obscuration due to a dust lane that is identified in absorption in optical, infrared, and X-ray. The dust lane is likely part of a ring of material which includes the molecular core within W40. In contrast to the likely ongoing star formation in the dust lane, the molecular core is inactive. The star cluster has a spherical morphology, an isothermal sphere density profile, and mass segregation down to 1.5 M<sub>sun</sub>. However, other cluster properties, including a <= 1 Myr age estimate and ongoing star formation, indicate that the cluster is not dynamically relaxed. X-ray diffuse emission and a powerful flare from a young stellar object are also reported in the reference paper. This table was created by the HEASARC in March 2011 based on electronic versions of Tables, 1, 2 and 4 of the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
17522. W UMa type and CAB stars dynamical evolution
ID:
ivo://CDS.VizieR/J/MNRAS/373/1483
Title:
W UMa type and CAB stars dynamical evolution
Short Name:
J/MNRAS/373/1483
Date:
21 Oct 2021
Publisher:
CDS
Description:
Orbital angular momentum (OAM, Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of and logJo-logP, logM-logP and logJo-logM were formed from 119 CAB and 102 W UMa stars. The log Jo-logM diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the logJo-logM diagram. Since the orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio, q, the rates of OAM loss (dlogJo/dt) and mass loss (dlogM/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the logJo-logM diagram. The evolution of q for a mass-losing detached system is unknown unless the mass-loss rate for each component is known. Assuming q is constant in the first approximation and using the mean decreasing rates of Jo and M from the kinematical ages of CAB stars, it has been predicted that 11, 23 and 39 per cent of current CAB stars would transform to W UMa systems if their nuclear evolution permits them to live 2, 4 and 6Gyr, respectively.
17523. W UMa-type contact binaries ages and masses
ID:
ivo://CDS.VizieR/J/MNRAS/437/185
Title:
W UMa-type contact binaries ages and masses
Short Name:
J/MNRAS/437/185
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recently, our understanding of the origin of W UMa-type contact binaries has become clearer. Initial masses of their components were successfully estimated by Yildiz and Dogan using a new method mainly based on observational properties of overluminous secondary components. In this paper, we continue to discuss the results and make computations for age and orbital evolution of these binaries. It is shown that the secondary mass, according to its luminosity, also successfully predicts the observed radius. While the current mass of the primary component is determined by initial masses, the current secondary mass is also a function of initial angular momentum. We develop methods to compute the age of A- and W-subtype W UMa-type contact binaries in terms of initial masses and mass according to the luminosity of the secondaries. Comparisons of our results with the mean ages from kinematic properties of these binaries and data pertaining to contact binaries in open and globular clusters have increased our confidence on this method. The mean ages of both A- and W-subtype contact binaries are found as 4.4 and 4.6Gyr, respectively. From kinematic studies, these ages are given as 4.5 and 4.4Gyr, respectively. We also compute orbital properties of A-subtype contact binaries at the time of the first overflow. Initial angular momentum of these binaries is computed by comparing them with the well-known detached binaries. The angular momentum loss rate derived in the present study for the detached phase is in very good agreement with the semi-empirical rates available in the literature. In addition to the limitations on the initial masses of W UMa-type contact binaries, it is shown that the initial period of these binaries is less than about 4.45d.
17524. WWFI g'-band obs. of bright cluster galaxies
ID:
ivo://CDS.VizieR/J/ApJS/247/43
Title:
WWFI g'-band obs. of bright cluster galaxies
Short Name:
J/ApJS/247/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observations of 170 local (z<~0.08) galaxy clusters in the northern hemisphere have been obtained with the Wendelstein Telescope Wide Field Imager (WWFI). We correct for systematic effects such as point-spread function broadening, foreground star contamination, relative bias offsets, and charge persistence. Background inhomogeneities induced by scattered light are reduced down to {Delta}SB>31 g' mag/arcsec^2^ by large dithering and subtraction of night-sky flats. Residual background inhomogeneities brighter than SB_{sigma}_<27.6 g' mag/arcsec^2^ caused by galactic cirrus are detected in front of 23% of the clusters. However, the large field of view allows discrimination between accretion signatures and galactic cirrus. We detect accretion signatures in the form of tidal streams in 22%, shells in 9.4%, and multiple nuclei in 47% of the brightest cluster galaxies (BCGs) and find two BCGs in 7% of the clusters. We measure semimajor-axis surface brightness profiles of the BCGs and their surrounding intracluster light (ICL) down to a limiting surface brightness of SB=30 g' mag/arcsec^2^. The spatial resolution in the inner regions is increased by combining the WWFI light profiles with those that we measured from archival Hubble Space Telescope images or deconvolved WWFI images. We find that 71% of the BCG+ICL systems have surface brightness (SB) profiles that are well described by a single Sersic function, whereas 29% require a double Sersic function to obtain a good fit. We find that BCGs have scaling relations that differ markedly from those of normal ellipticals, likely due to their indistinguishable embedding in the ICL.
17525. WWFI g'-band obs. of bright galaxy clusters
ID:
ivo://CDS.VizieR/J/ApJS/252/27
Title:
WWFI g'-band obs. of bright galaxy clusters
Short Name:
J/ApJS/252/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explore several ways to dissect brightest cluster galaxies (BCGs) and their surrounding intracluster light (ICL) using a surface brightness (SB) cut, a luminosity cut, excess light above a de Vaucouleurs profile, or a double Sersic decomposition. Assuming that all light above M{<}-21.85g'mag is attributable to the ICL, we find that an average fraction of f_ICL_^MT^=71+/-22% of all diffuse light centered on the BCG belongs to the ICL. Likewise, if we assume that all light fainter than SB>27g'mag/arcsec^2^ belongs to the ICL, the average ICL fraction is f_ICL_^SB27^=34+/-19% . After fitting a de Vaucouleurs profile to the inner parts of the SB profile, we detect excess light at large radii, corresponding to an average ICL fraction of f_ICL_^DV^=48+/-20% . Finally, by decomposing the SB profile into two Sersic functions, we find an average ICL fraction of f_ICL_^Sx^=52+/-21% associated with the outer Sersic component. Our measured ICL and BCG+ICL luminosities agree well with predictions from high-resolution simulations where the outer Sersic component traces the unrelaxed, accreted stellar material. BCG and ICL properties defined in this way are correlated with cluster parameters to study the coevolution of BCGs, ICL, and their host clusters. We find positive correlations between BCG+ICL brightness and cluster mass, cluster velocity dispersion, cluster radius, and integrated satellite brightness, confirming that BCG/ICL growth is indeed coupled with cluster growth. On average, the ICL is better aligned than the BCG with the host cluster in terms of position angle, ellipticity, and centering. That makes it a potential dark-matter tracer.
17526. X- and gamma-ray fluxes of {gamma}-ray-loud blazars
ID:
ivo://CDS.VizieR/J/A+A/436/799
Title:
X- and gamma-ray fluxes of {gamma}-ray-loud blazars
Short Name:
J/A+A/436/799
Date:
21 Oct 2021
Publisher:
CDS
Description:
We determined the basic parameters, such as the central black hole mass (M), the boosting factor (or Doppler factor) ({delta}) the propagation angle ({Phi}) and the distance along the axis to the site of {gamma}-ray production (d) for 23 {gamma}-ray-loud blazars using their available variability timescales.
17527. X and {gamma} spectral indexes of Fermi blazars
ID:
ivo://CDS.VizieR/J/ApJ/761/125
Title:
X and {gamma} spectral indexes of Fermi blazars
Short Name:
J/ApJ/761/125
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, a sample of 451 blazars (193 flat spectrum radio quasars (FSRQs), 258 BL Lacertae objects) with corresponding X-ray and Fermi {gamma}-ray data is compiled to investigate the correlation both between the X-ray spectral index and the {gamma}-ray spectral index and between the spectral index and the luminosity, and to compare the spectral indexes {alpha}_X_, {alpha}_{gamma}_, {alpha}_X{gamma}_, and {alpha}_{gamma}X{gamma}_ for different subclasses. We also investigated the correlation between the X-ray and the {gamma}-ray luminosity.
17528. XAO AGN Flux Monitoring Data
ID:
ivo://xaovo/liujun/liujun/q
Title:
XAO AGN Flux Monitoring Data
Short Name:
liujun_web
Date:
25 Jun 2024 10:32:03
Publisher:
Xinjiang Astronomical Observatory,CAS
Description:
Active Galactic Nuclei (AGNs) are extragalactic objects characterized by extremely complex physical processes and strong temporal flux variability over almost the whole electromagnetic spectrum, which play a very important role in studying the formation and evolution of galaxies, cosmology and many other astrophysical problems. Flux variability is one of the most remarkable observational characteristics of AGNs and the variability time scales are from minutes to dozens of years. Multi-wavelength flux monitoring is the main means to study the nature of AGN flux variability. In order to systematically study the total flux variability of AGNs in radio band, we launched a long-term program, which is called the quasi- Simultaneous Multiwavelength Monitoring of AGNs with the Nanshan 26-m radio telescope of Xinjiang Astronomical Observatory (XAO), namely SMMAN program. The monitoring data were acquired monthly with the cross-scan mode at C-band (4.8 GHz) and K-band (23.6 GHz) for a sample of about 100 AGNs selected from Fermi-LAT suvery. Additionally, we also conducted weekly monitoring observations or Intra-Day Vairibility (IDV) observations for some of flaring Blazars to reveal their more complex variability time scales.
17529. XAO Pulsar Data Query
ID:
ivo://xaovo/pul/pulsar/q
Title:
XAO Pulsar Data Query
Short Name:
Pulsar_web
Date:
02 Jan 2025 14:01:21
Publisher:
Xinjiang Astronomical Observatory,CAS
Description:
The pulsar timing data were obtained with the Nanshan 25M radio telescope. Our observations, which commenced in January 2000, have been made using a dual-channel room-temperature receiver with a bandwidth of 320 MHz centered at 1540 MHz before June 2002. The de-dispersion was provided by a 2X128X2.5 MHz analog filter-bank. A cryogenic receiver was mounted in July 2002, which increases the sensitivity to 0.5 mJy. In January 2010, a digital filter-bank (DFB) system came into operation. The higher time resolution allows us to monitor about 280 pulsars, including ten millisecond-pulsars (MSP). The format of the DFB data is "Psrfit". The "psrchive" program could reads and analyzes the data. Timing observations of 74 pulsars have been regularly carried out between 2002 July to 2009 December. These 74 pulsars have been monitored approximately once every 9d using a dual-channel cryogenic system that receives orthogonal linear polarizations at the central observing frequency of 1540 MHz. The folded profiles obtained are released in format PSRFITS for timing analysis, the file name extension is .FTp. Users can enter "~*.FTp*" in "Product key" filed to search and download it. Non-public data could be used with the permission of Dr. Shengnan Sun (sunshengnan@xao.ac.cn), please send an email for your request.
17530. XAO SF Data Query
ID:
ivo://xaovo/wugang/wugang/q
Title:
XAO SF Data Query
Short Name:
wugang_web
Date:
25 Jun 2024 10:32:03
Publisher:
Xinjiang Astronomical Observatory,CAS
Description:
The molecular spectrum lines data include mainly ammonia and water masers lines at 1.3cm band, as well as formaldehyde and recombination lines at 6cm band observed towards both our Galactic plane and nearby molecular clouds and star-forming regions.

Limit your search

more »

more »

more »

more »

more »

more »