- ID:
- ivo://CDS.VizieR/J/A+A/315/348
- Title:
- BVI photometry of two Orion galaxies
- Short Name:
- J/A+A/315/348
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two relatively faint (B=15.7 and B=18.4mag, respectively), low velocity (+276 and +322km/s) galaxies were imaged with a CCD in the B, V, I bands at the prime focus of the 6m telescope on 16 October 1993. By means of the brightest stars we estimated their distances to be 6.4 and 5.5(+/-2)Mpc, assuming a galactic extinction of 2.7 and 2.9mag, respectively. We note that these isolated irregular dwarfs are located to a high Supergalactic latitude, -63deg, and their low radial velocities may be the result of a retarded expansion along the polar axis of the Local cloud of galaxies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/660/81
- Title:
- BViz photometry of TKRS blue galaxies in GOODS-N
- Short Name:
- J/ApJ/660/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the radius-luminosity (R-L) relation for blue galaxies in the Team Keck Redshift Survey (TKRS) of GOODS-N. We compare with a volume-limited, Sloan Digital Sky Survey sample and find that the R-L relation has evolved to lower surface brightness since z=1. Based on the detection limits of GOODS, this cannot be explained by incompleteness in low surface brightness galaxies. Number density arguments rule out a pure radius evolution. It can be explained by a radius-dependent decline in B-band luminosity with time.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A58
- Title:
- B2 0258+35 VLA and VLBI HI absorption spectra
- Short Name:
- J/A+A/629/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low-luminosity radio-loud active galactic nuclei (AGN) are of importance in studies concerning feedback from radio AGN since a dominant fraction of AGN belong to this class. We report high-resolution Very Large Array (VLA) and European VLBI Network (EVN) observations of HI 21cm absorption from a young, compact steep-spectrum radio source, B2 0258+35, nested in the early-type galaxy NGC 1167, which contains a 160kpc HI disc. Our VLA and EVN HI absorption observations, modelling, and comparison with molecular gas data suggest that the cold gas in the centre of NGC 1167 is very turbulent (with a velocity dispersion of ~90km/s) and that this turbulence is induced by the interaction of the jets with the interstellar medium (ISM). Furthermore, the ionised gas in the galaxy shows evidence of shock heating at a few kpc from the radio source. These findings support the results from numerical simulations of radio jets expanding into a clumpy gas disc, which predict that the radio jets in this case percolate through the gas disc and drive shocks into the ISM at distances much larger than their physical extent. These results expand the number of low-luminosity radio sources found to impact the surrounding medium, thereby highlighting the possible relevance of these AGN for feedback.
394. B3-VLA CSS sample
- ID:
- ivo://CDS.VizieR/J/A+A/426/463
- Title:
- B3-VLA CSS sample
- Short Name:
- J/A+A/426/463
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of VLBA observations at 6 and 3.6cm for eighteen Compact Steep Spectrum radio sources (CSS) from the B3-VLA CSS sample. In most cases these VLBA images display a "Double/Triple" morphology, and the core is unambiguously detected in seven sources. Multifrequency images allow us to study the spectral properties of the individual source components and to constrain the spectral age. In lobe-dominated sources the radiative ages deduced from the synchrotron theory are in the range of up 5x10^3^ years, if equipartition magnetic field is assumed. Polarized emission is detected at a few percent level for two sources only. They were the only two sources displaying polarized emission in VLA A configuration data, and this implies that beam depolarization is not effective in reducing the integrated fractional polarization for these sources.
- ID:
- ivo://CDS.VizieR/J/A+A/406/579
- Title:
- B3-VLA sample. III. Polarisation
- Short Name:
- J/A+A/406/579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Polarisation parameters are presented for 192 radiosources of the B3-VLA sample at 1.4, 2.7, 4.8, 10.5GHz. The polarisation has been measured with Effelsberg radiotelescope for 2.7, 4.8, 10.5GHz, while the 1.4 polarization is from NVSS (Cat. <VIII/65>) survey. Rotation Measures (RM) are presented for 143 radiosources.
- ID:
- ivo://CDS.VizieR/J/A+A/435/863
- Title:
- B3-VLA sample. IV: 74MHz flux densities
- Short Name:
- J/A+A/435/863
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 74MHz flux densities are presented for 365 radiosources of the B3-VLA sample. Data were obtained as a by-product of the VLA A-array 74MHz survey of Tschager et al. (2003, Cat. <J/A+A/402/171>). These A-array data provide the first morphological information at this low frequency.
- ID:
- ivo://CDS.VizieR/J/ApJ/652/313
- Title:
- BV phot. of a detached eclipsing binary in M 33
- Short Name:
- J/ApJ/652/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first direct distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project. Located in the OB 66 association at coordinates (RA,DE)=(01:33:46.17,+30:44:39.9) for J2000.0, it was one of the most suitable detached eclipsing binaries found by DIRECT for distance determination, given its apparent magnitude and orbital period. We obtained follow-up BV time-series photometry, JHKs photometry, and optical spectroscopy from which we determined the parameters of the system. It contains two O7 main-sequence stars, with masses of 33.4+/-3.5 and 30.0+/-3.3M_{sun}_ and radii of 12.3+/-0.4 and 8.8+/-0.3R_{sun}_, respectively. We derive temperatures of 37000+/-1500 and 35600+/-1500K. Using BVRJHKs photometry for the flux calibration, we obtain a distance modulus of 24.92+/-0.12mag (964+/-54kpc), which is 0.3mag longer than the Key Project distance to M33. We discuss the implications of our result and the importance of establishing M33 as an independent rung on the cosmological distance ladder.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A10
- Title:
- (BV) photometry in Carina dSph
- Short Name:
- J/A+A/572/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep photometry of the Carina dwarf Spheroidal galaxy in the B,V filters from CTIO/MOSAIC, out to and beyond the tidal radius of r_ell_~0.48{deg}. The accurately calibrated photometry is combined with spectroscopic metallicity distributions of Red Giant Branch stars to determine the detailed star formation and chemical evolution history of Carina. The star formation history confirms the episodic formation history of Carina and quantifies the duration and strength of each episode in great detail, as a function radius from the centre. Two main episodes of star formation occurred at old (>8Gyr) and intermediate (2-8Gyr) ages, both enriching stars starting from low metallicities ([Fe/H]<-2dex). By dividing the SFH into two components, we determine that 60+/-9 percent of the total number of stars formed within the intermediate age episode. Furthermore, within the tidal radius (0.48{deg} or 888pc) a total mass in stars of 1.07+/-0.08x10^6^M_{sun}_ was formed, giving Carina a stellar mass-to-light ratio of 1.8+/-0.8. Combining the detailed star formation history with spectroscopic observations of RGB stars, we are able to determine the detailed age-metallicity relation of each episode and the timescale of alpha-element evolution of Carina from individual stars. The oldest episode displays a tight age-metallicity relation during ~6Gyr with steadily declining alpha-element abundances and a possible alpha-element knee visible at [Fe/H]~-2.5dex. The intermediate age sequence displays a more complex age-metallicity relation starting from low metallicity and a sequence in alpha-element abundances with a slope much steeper than observed in the old episode, starting from [Fe/H]=-1.8dex and [Mg/Fe]~0.4dex and declining to Mg-poor values ([Mg/Fe]<-0.5dex). This indicates clearly that both episodes of star formation formed from gas with different abundance patterns , inconsistent with simple evolution in an isolated system.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1840
- Title:
- BV photometry in Carina dwarf galaxy
- Short Name:
- J/AJ/115/1840
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed deep B and V photometry of the Carina dwarf spheroidal galaxy reaching below the old main-sequence turnoff to V~25. Using simulated color-magnitude diagrams to model a range of star formation scenarios, we have extracted a detailed, global star formation history. Carina experienced three significant episodes of star formation at ~15, 7, and 3Gyr. Contrary to the generic picture of galaxy evolution, however, the bulk of star formation, at least 50%, occurred during the episode 7Gyr ago, which may have lasted as long as 2Gyr. For unknown reasons, Carina formed only 10%-20% of its stars at an ancient epoch and then remained quiescent for more than 4 Gyr. The remainder (~30%) formed relatively recently, only 3Gyr ago. Interest in the local population of dwarf galaxies has increased lately because of their potential importance in the understanding of faint galaxy counts. We surmise that objects like Carina, which exhibits the most extreme episodic behavior of any of the dwarf spheroidal companions to the Galaxy, are capable of contributing to the observed excess of blue galaxies at B~24 only if the star formation occurred instantaneously.
- ID:
- ivo://CDS.VizieR/J/ApJ/710/1664
- Title:
- BV photometry in Leo IV and Leo V dSphs
- Short Name:
- J/ApJ/710/1664
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep photometry in two 1{deg}x1{deg} fields covering the close pair of dwarf spheroidal galaxies Leo IV and Leo V and part of the area in between. From the distribution of likely red giant branch (RGB) and horizontal-branch (HB) stars in the data set, we find that both Leo IV and Leo V are significantly larger than indicated by previous measurements based on shallower data. With a half-light radius of r_h_=4.6'+/-0.8' (206+/-36pc) and r_h_=2.6'+/-0.6' (133+/-31pc), respectively, both systems are now well within the physical size bracket of typical dwarf spheroidal Milky Way satellites. Both are also found to be significantly elongated with an ellipticity of {epsilon}~0.5, a characteristic shared by many of the fainter (M_V_>-8) Milky Way dwarf spheroidals. The large spatial extent of our survey allows us to search for extra-tidal features in the area between the two dwarf galaxies with unprecedented sensitivity. The spatial distribution of candidate RGB and HB stars in this region is found to be non-uniform at the ~3{sigma} level. We investigate different scenarios to explain the close proximity of Leo IV and Leo V, and the possible tidal bridge between them.