- ID:
- ivo://CDS.VizieR/VIII/40
- Title:
- GB6 catalog of radio sources
- Short Name:
- VIII/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Green Bank 4.85GHz (lambda~6cm) survey was made with the NRAO seven-beam receiver on the (former) 91m telescope during 1986 November and 1987 October. The final set of sky maps covering the declination band 0deg<Dec.<+75deg was constructed with data from both epochs. Its noise and position errors are nearly a factor of 2^(1/2)^ smaller than in the epoch 1987 maps, from which the 87GB catalog <VIII/14> of 54,579 sources stronger than S~25mJy was extracted. Therefore, we used the new maps to make the GB6 catalog of 75,162 discrete sources with angular sizes phi<=10.5arcmin and flux densities S>=18mJy. This catalog is available in machine-readable versions with either B1950 or J2000 positions and as a printed book with B1950 positions. The GB6 weighted differential source counts S^(5/2)n(S) between 18 mJy and 7Jy agree well with evolutionary models based on independent data.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/443/1044
- Title:
- GBT HI observations of 1194 spirals
- Short Name:
- J/MNRAS/443/1044
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI 21cm observations of 1194 galaxies out to a redshift of 10000km/s selected as inclined spirals (i>~60{deg}) from the 2MASS redshift survey. These observations were carried out at the National Radio Astronomy Observatory Robert C. Byrd Green Bank Telescope (GBT). This observing programme is part of the 2MASS Tully-Fisher (2MTF) survey. This project will combine Hi widths from these GBT observations with those from further dedicated observing at the Parkes Telescope, from the Arecibo Legacy Fast Arecibo L-band Feed Array survey at Arecibo, and S/N>10 and spectral resolution v_res_<10km/s published widths from a variety of telescopes. We will use these Hi widths along with 2MASS photometry to estimate Tully-Fisher distances to nearby spirals and investigate the peculiar velocity field of the local Universe. In this paper, we report on detections of neutral hydrogen in emission in 727 galaxies, and measure good signal to noise and symmetric HI global profiles suitable for use in the Tully-Fisher relation in 484.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/39
- Title:
- GBT HI obs. of ultradiffuse galaxies
- Short Name:
- J/ApJ/902/39
- Date:
- 10 Mar 2022 13:55:53
- Publisher:
- CDS
- Description:
- We present neutral hydrogen (HI) observations using the Robert C. Byrd Green Bank Telescope (GBT) of 70 optically detected UDG candidates in the Coma region from the Systematically Measuring Ultra-Diffuse Galaxies survey (SMUDGes). We detect HI in 18 targets, confirming nine to be gas-rich UDGs and the remainder to be foreground dwarfs. None of our HI-detected UDGs are Coma Cluster members and all but one are in low-density environments. The HI-detected UDGs are bluer and have more irregular morphologies than the redder, smoother candidates not detected in HI, with the combination of optical color and morphology being a better predictor of gas richness than either parameter alone. There is little visual difference between the gas-rich UDGs and the foreground dwarfs in the SMUDGes imaging, and distances are needed to distinguish between them. We find that the gas richnesses of our HI-confirmed UDGs and those from other samples scale with their effective radii in two stellar mass bins, possibly providing clues to their formation. We attempt to place our UDGs on the baryonic Tully-Fisher relation (BTFR) using optical ellipticities and turbulence-corrected HI line widths to estimate rotation velocities, but the potential systematics associated with fitting smooth Sersic profiles to clumpy, low-inclination disks of low surface brightness precludes a meaningful analysis of potential BTFR offsets. These observations are a pilot for a large campaign now under way at the GBT to use the HI properties of gas-rich UDGs to quantitatively constrain how these galaxies form and evolve.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/80
- Title:
- GBT 350MHz survey. I. 13 new pulsars
- Short Name:
- J/ApJ/763/80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Over the summer of 2007, we obtained 1191hr of "drift-scan" pulsar search observations with the Green Bank Telescope at a radio frequency of 350MHz. Here we describe the survey setup, search procedure, and the discovery and follow-up timing of 13 pulsars. Among the new discoveries, one (PSR J1623-0841) was discovered only through its single pulses, two (PSRs J1327-0755 and J1737-0814) are millisecond pulsars, and another (PSR J2222-0137) is a mildly recycled pulsar. PSR J1327-0755 is a 2.7ms pulsar at a dispersion measure (DM) of 27.9pc/cm3 in an 8.7 day orbit with a minimum companion mass of 0.22M_{sun}_. PSR J1737-0814 is a 4.2ms pulsar at a DM of 55.3pc/cm3 in a 79.3 day orbit with a minimum companion mass of 0.06M_{sun}_. PSR J2222-0137 is a 32.8ms pulsar at a very low DM of 3.27pc/cm3 in a 2.4 day orbit with a minimum companion mass of 1.11M_{sun}_. It is most likely a white-dwarf-neutron-star system or an unusual low-eccentricity double neutron star system. Ten other pulsars discovered in this survey are reported in the companion paper Lynch et al. (2013ApJ...763...81L).
- ID:
- ivo://CDS.VizieR/J/ApJS/177/255
- Title:
- GBT multiwavelength survey of Galactic center
- Short Name:
- J/ApJS/177/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a radio continuum survey of the central 4{deg}x1{deg} with the 100m Green Bank Telescope (GBT) at wavelengths of 3.5, 6, 20, and 90cm. The 3.5 and 6cm surveys are the most sensitive and highest resolution single-dish surveys made of the central degrees of our Galaxy. We present catalogs of compact and extended sources in the central 4{deg} of our Galaxy, including detailed spectral index studies of all sources. The analysis covers star-forming regions such as Sgr B and Sgr C, where we find evidence of a mixture of thermal and nonthermal emission. The analysis quantifies the relative contribution of thermal and nonthermal processes to the radio continuum flux density toward the Galactic center (GC) region. In the central 4{deg}x1{deg} of the GC, the thermal and nonthermal flux fractions for all compact and diffuse sources are 28%/72% at 3.5cm and 19%/81% at 6cm. The total flux densities from these sources are 783+/-52 and 1063+/-93Jy at 3.5 and 6cm, respectively, excluding the contribution of Galactic synchrotron emission.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A34
- Title:
- GC hot UV-bright stars model spectra
- Short Name:
- J/A+A/627/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a census of the UV-bright population in 78 globular clusters using wide-field UV telescopes. This population includes a variety of phases of post-horizontal branch (HB) evolution, including hot post-asymptotic giant branch (AGB) stars, and post-early AGB stars. There are indications that old stellar systems like globular clusters produce fewer post-(early) AGB stars than currently predicted by evolutionary models, but observations are still scarce. We wish to derive effective temperatures, surface gravities, and helium abundances of the luminous hot UV-bright stars in these clusters to determine their evolutionary status and compare the observed numbers to predictions from evolutionary theory. We obtained FORS2 spectroscopy of 11 of these UV-selected objects (covering a range of -2.3<[Fe/H]<-1.0), which we (re-)analysed together with previously observed data. We used model atmospheres of different metallicities, including super-solar ones. Where possible, we verified our atmospheric parameters using UV spectrophotometry and searched for metal lines in the optical spectra. We calculated evolutionary sequences for four metallicity regimes and used them together with information about the HB morphology of the globular clusters to estimate the expected numbers of post-AGB stars. We find that metal-rich model spectra are required to analyse stars hotter than 40000 K. Seven of the eleven new luminous UV-bright stars are post-AGB or post-early AGB stars, two are evolving away from the HB, one is a foreground white dwarf, and another is a white dwarf merger. Taking into account published information on other hot UV-bright stars in globular clusters, we find that the number of observed hot post-AGB stars generally agrees with the predicted values, although the numbers are still low. Spectroscopy is clearly required to identify the evolutionary status of hot UV-bright stars. For hotter stars, metal-rich model spectra are required to reproduce their optical and UV spectra, which may affect the flux contribution of hot post-AGB stars to the UV spectra of evolved populations. Adding published information on other hot UV-bright stars in globular clusters, we find that the number of observed hot post-AGB stars generally agrees with the predicted values, although the numbers are still low.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A121
- Title:
- G203.7+11.5 21cm and 11cm intensity maps
- Short Name:
- J/A+A/641/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In soft X-rays, the Monogem ring is an object with a diameter of 25{deg} located in the Galactic anti-centre. It is believed to be a faint, evolved, local supernova remnant. It is not seen at radio wavelengths, as other large supernova remnants are. We study a narrow about 4.5D long, faint Halpha-filament, G203.7+11.5, that is seen towards the centre of the Monogem ring. It causes depolarisation and excessive Faraday rotation of radio polarisation data. Polarisation observations at 11cm and 21cm with the Effelsberg 100-m telescope were analysed.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A36
- Title:
- G53.541-0.011 ^12^CO and ^13^CO data cubes
- Short Name:
- J/A+A/569/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate how a large-scale infrared bubble centered at l=53.9{deg} and b=0.2{deg} forms, and to study if star formation is taking place at the periphery of the bubble, we performed a multiwavelength study. Using the data from the Galactic Ring Survey (GRS) and Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), we performed a study of a large-scale infrared bubble with a size of about 16pc at a distance of 2.0kpc. We present the ^12^CO J=1-0, ^13^CO J=1-0, and C^18^O J=1-0 observations of HII region G53.54-0.01 (Sh2-82) obtained at the Purple Mountain Observation (PMO) 13.7m radio telescope to investigate the detailed distribution of associated molecular material. In addition, we also used radiorecombination line and VLA data. To select young stellar objects (YSOs) consistent with this region, we used the GLIMPSE I catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/595/A88
- Title:
- G345.45+1.50 ^13^CO(3-2) clumps
- Short Name:
- J/A+A/595/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ring-like structures in the interstellar medium (ISM) are commonly associated with high-mass stars. Kinematic studies of large structures in giant molecular clouds (GMCs) toward these ring-like structures may help us to understand how massive stars form. The origin and properties of the ring-like structure G345.45+1.50 is investigated through observations of the ^13^CO(3-2) line. The aim of the observations is to determine the kinematics in the region and to compare physical characteristics estimated from gas emission with those previously determined using dust continuum emission. This area in the sky is well suited for studies like this because the ring is located 1.5{deg} above the Galactic plane at 1.8kpc from the Sun, thus molecular structures are rarely superposed on our line of sight, which minimizes confusion effects that might hinder identifying of individual molecular condensations. The ^13^CO(3-2) line was mapped toward the whole ring using the Atacama Pathfinder Experiment (APEX) telescope. The observations cover 17'x20' in the sky with a spatial resolution of 0.2pc and an rms of ~1K at a spectral resolution of 0.1km/s. The ring is found to be expanding with a velocity of 1.0km/s, containing a total mass of 6.9x10^3^M_{sun}_, which agrees well with that determined using 1.2mm dust continuum emission. An expansion timescale of ~3x10^6^yr and a total energy of ~7x10^46^erg are estimated. The origin of the ring might have been a supernova explosion, since a 35.5cm source, J165920-400424, is located at the center of the ring without an infrared counterpart. The ring is fragmented, and 104 clumps were identified with diameters of between 0.3 and 1.6pc, masses of between 2.3 and 7.5x10^2^M_{sun}_, and densities of between ~10^2^ and ~10^4^cm^-3^. At least 18% of the clumps are forming stars, as is shown in infrared images. Assuming that the clumps can be modeled as Bonnor-Ebert spheres, 13 clumps are collapsing, and the rest of them are in hydrostatic equilibrium with an external pressure with a median value of 4x10^4^K/cm^3^. In the region, the molecular outflow IRAS 16562-3959 is identified, with a velocity range of 38.4km/s, total mass of 13M_{sun}_, and kinematic energy of 7x10^45^erg. Finally, five filamentary structures were found at the edge of the ring with an average size of 3pc, a width of 0.6pc, a mass of 2x10^2^M_{sun}_, and a column density of 6x10^21^cm^-2^.
- ID:
- ivo://CDS.VizieR/J/AJ/153/114
- Title:
- GCs in 27 nearby ETGs from the SLUGGS survey
- Short Name:
- J/AJ/153/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here, we present positions and radial velocities for over 4000 globular clusters (GCs) in 27 nearby early-type galaxies from the SLUGGS survey. The SLUGGS survey is designed to be representative of elliptical and lenticular galaxies in the stellar mass range 10<logM_*_/M_{sun}_<11.7. The data have been obtained over many years, mostly using the very stable multi-object spectrograph DEIMOS on the Keck II 10 m telescope. Radial velocities are measured using the calcium triplet lines, with a velocity accuracy of +/-10-15 km/s. We use phase space diagrams (i.e., velocity-position diagrams) to identify contaminants such as foreground stars and background galaxies, and to show that the contribution of GCs from neighboring galaxies is generally insignificant. Likely ultra-compact dwarfs are tabulated separately. We find that the mean velocity of the GC system is close to that of the host galaxy systemic velocity, indicating that the GC system is in overall dynamical equilibrium within the galaxy potential. We also find that the GC system velocity dispersion scales with host galaxy stellar mass, in a similar manner to the Faber-Jackson relation for the stellar velocity dispersion. Publication of these GC radial velocity catalogs should enable further studies in many areas, such as GC system substructure, kinematics, and host galaxy mass measurements.