- ID:
- ivo://CDS.VizieR/J/AJ/133/2669
- Title:
- Velocity and H{alpha} width of 22 Vul
- Short Name:
- J/AJ/133/2669
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 22 Vul system is important for studying the winds and chromospheres of cool evolved stars because the G4 I component is rotating rapidly and probably faster than synchronously. We discuss the system's physical properties in the context of a wide range of constraints on them and propose values that may be marginally better than previous ones. We use H{alpha} spectroscopy to assess the variability of the cool star's wind, and archival IUE observations to measure variation of density in the wind and rotation of the chromosphere.
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- ID:
- ivo://CDS.VizieR/J/ApJ/733/46
- Title:
- Velocity measurements in Segue 1
- Short Name:
- J/ApJ/733/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a comprehensive Keck/DEIMOS spectroscopic survey of the ultra-faint Milky Way satellite galaxy Segue 1. We have obtained velocity measurements for 98.2% of the stars within 67pc (10', or 2.3 half-light radii) of the center of Segue 1 that have colors and magnitudes consistent with membership, down to a magnitude limit of r=21.7. Based on photometric, kinematic, and metallicity information, we identify 71 stars as probable Segue 1 members, including some as far out as 87pc. After correcting for the influence of binary stars using repeated velocity measurements, we determine a velocity dispersion of 3.7^+1.4^_-1.1_km/s. The mass within the half-light radius is 5.8^+8.2^_-3.1_x10^5^M_{sun}_. The stellar kinematics of Segue 1 require very high mass-to-light ratios unless the system is far from dynamical equilibrium, even if the period distribution of unresolved binary stars is skewed toward implausibly short periods. With a total luminosity less than that of a single bright red giant and a V-band mass-to-light ratio of 3400M_{sun}_/L_{sun}_, Segue 1 is the darkest galaxy currently known.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/26
- Title:
- Very low-z SDSS galaxies with H{alpha} emission
- Short Name:
- J/ApJ/765/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong H{alpha} emitters (HAEs) dominate the z~4 Lyman-break galaxy (LBG) population. We have identified local analogs of these HAEs using the Sloan Digital Sky Survey. At z<0.4, only 0.04% of the galaxies are classified as HAEs with H{alpha} equivalent widths (>~500{AA}) comparable to that of z~4 HAEs. Local HAEs have lower stellar mass and lower ultraviolet (UV) luminosity than z~4 HAEs, yet the H{alpha}-to-UV luminosity ratio, as well as their specific star formation rate, is consistent with that of z~4 HAEs, indicating that they are scaled-down versions of high-z star-forming galaxies. Compared to the previously studied local analogs of LBGs selected using rest-frame UV properties, local HAEs show similar UV luminosity surface density, weaker D_n_(4000) break, lower metallicity, and lower stellar mass. This implies that the local HAEs are less evolved galaxies than the traditional Lyman break analogs. In the stacked spectrum, local HAEs show a significant He II{lambda}4686 emission line suggesting a population of hot, massive stars similar to that seen in some Wolf-Rayet galaxies. Low [N II]/[O III] line flux ratios imply that local HAEs are inconsistent with being systems that host bright active galactic nuclei. Instead, it is highly likely that local HAEs are galaxies with an elevated ionization parameter, either due to a high electron density or large escape fraction of hydrogen ionizing photons as in the case of Wolf-Rayet galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/466/277
- Title:
- VLT-FLAMES survey of massive stars
- Short Name:
- J/A+A/466/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of high-resolution FLAMES spectra of approximately 50 early B-type stars in three young clusters at different metallicities, NGC 6611 in the Galaxy, N 11 in the Large Magellanic Cloud (LMC) and NGC 346 in the Small Magellanic Cloud (SMC). Using the TLUSTY non-LTE model atmospheres code, atmospheric parameters and photospheric abundances (C, N, O, Mg and Si) of each star have been determined. These results represent a significant improvement on the number of Magellanic Cloud B-type stars with detailed and homogeneous estimates of their atmospheric parameters and chemical compositions. The relationships between effective temperature and spectral type are discussed for all three metallicity regimes, with the effective temperature for a given spectral type increasing as one moves to a lower metallicity regime. Additionally the difficulties in estimating the microturbulent velocity and the anomalous values obtained, particularly in the lowest metallicity regime, are discussed. Our chemical composition estimates are compared with previous studies, both stellar and interstellar with, in general, encouraging agreement being found.
- ID:
- ivo://CDS.VizieR/J/A+A/471/625
- Title:
- VLT-FLAMES survey of massive stars
- Short Name:
- J/A+A/471/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of high resolution VLT-FLAMES spectra of 61 B-type stars with relatively narrow-lined spectra located in 4 fields centered on the Milky Way clusters; NGC3293 and NGC4755 and the Large and Small Magellanic cloud clusters; NGC2004 and NGC330. For each object a quantitative analysis was carried out using the non-LTE model atmosphere code TLUSTY; resulting in the determination of their atmospheric parameters and photospheric abundances of the dominant metal species (C, N, O, Mg, Si, Fe). The results are discussed in relation to our earlier work on 3 younger clusters in these galaxies; NGC6611, N11 and NGC346 paying particular attention to the nitrogen abundances which are an important probe of the role of rotation in the evolution of stars. This work along with that of the younger clusters provides a consistent dataset of abundances and atmospheric parameters for over 100 B-type stars in the three galaxies. We provide effective temperature scales for B-type dwarfs in all three galaxies and for giants and supergiants in the SMC and LMC. In each galaxy a dependence on luminosity is found between the three classes with the unevolved dwarf objects having significantly higher effective temperatures. A metallicity dependence is present between the SMC and Galactic dwarf objects, and whilst the LMC stars are only slightly cooler than the SMC stars, they are significantly hotter than their Galactic counterparts.
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/28
- Title:
- VLT Lyman-break galaxy redshift survey. II.
- Short Name:
- J/MNRAS/414/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured redshifts for 243 z~~3 quasars in nine Very Large Telescope (VLT) Visible Imaging and Multi-Object Spectrograph (VIMOS) Lyman-break galaxy (LBG) redshift survey areas, each of which is centred on a known bright quasar. Using the spectra of these quasars, we measure the cross-correlation between neutral hydrogen gas causing the Ly{alpha} forest and 1020 LBGs at z~~3.
- ID:
- ivo://CDS.VizieR/J/A+A/421/539
- Title:
- VLT spectroscopy of Tol 1214-277 & Tol 65
- Short Name:
- J/A+A/421/539
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VLT spectroscopic observations with different spectral resolutions and different slit orientations of the two metal-deficient blue compact dwarf (BCD) galaxies Tol 1214-277 and Tol 65. The oxygen abundances in the brightest HII regions of Tol 1214-277 and Tol 65 are found to be 12+logO/H=7.55+/-0.01 and 7.54+/-0.01, or Z_{sun}_/24. The nitrogen-to-oxygen abundance ratios in the two galaxies are logN/O=-1.64+/-0.03 and -1.60+/-0.02 and lie in the narrow range found for other most metal-deficient BCDs. The helium mass fraction derived in several HII regions in both galaxies is consistent with a high primordial helium mass fraction, Yp~0.244. We confirm the detection of the high-ionization forbidden emission line [FeV]4227 in the spectrum of Tol 1214-277. Additionally, weak [NeIV]4725, [FeVI]5146,5177, and [FeVII]5721,6087 emission lines are detected in the high-resolution spectrum of Tol 1214-277. The detection of these lines implies the presence of hard radiation with photon energy in the range ~4-8Ryd. Emission lines are detected in the spectra of eight galaxies in the fields of Tol 1214-277 and Tol 65. Seven of these galaxies are background objects, while one galaxy has a redshift close to that of Tol 1214-277. Situated at a projected distance of ~14.5kpc from Tol 1214-277, this galaxy is probably a companion of the BCD.
- ID:
- ivo://CDS.VizieR/J/ApJ/815/4
- Title:
- V899 Mon long-term monitoring
- Short Name:
- J/ApJ/815/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of V899 Mon (a new member in the FUors/EXors family of young low-mass stars undergoing outburst), based on our long-term monitoring of the source starting from 2009 November to 2015 April. Our optical and near-infrared photometric and spectroscopic monitoring recorded the source transitioning from its first outburst to a short-duration quiescence phase (<1yr), and then returning to a second outburst. We report here the evolution of the outflows from the inner region of the disk as the accretion rate evolved in various epochs. Our high-resolution (R~37000) optical spectrum could resolve interesting clumpy structures in the outflow traced by various lines. Change in far-infrared flux was also detected between two outburst epochs. Based on our observations, we constrained various stellar and envelope parameters of V899 Mon, as well as the kinematics of its accretion and outflow. The photometric and spectroscopic properties of this source fall between classical FUors and EXors. Our investigation of V899 Mon hints at instability associated with magnetospheric accretion being the physical cause of the sudden short-duration pause of the outburst in 2011. It is also a good candidate to explain similar short-duration pauses in outbursts of some other FUors/EXors sources.
- ID:
- ivo://CDS.VizieR/J/A+AS/122/43
- Title:
- V694 Mon plate spectra
- Short Name:
- J/A+AS/122/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the photographic spectral observations of MWC560 carried out in the period 1990-1993. The evolution of the spectrum, the changes in the radial velocities of the different line systems, as well as the variations in the equivalent widths of the different Balmer absorption components, are given and briefly discussed. The suggestion that the hot component of MWC560 ejects high-velocity, highly-collimated jets along the line of sight, is in very good agreement with the observations. All the results, including the variations in the shapes, velocities and equivalent widths of the strong-shifted Balmer absorptions, confirm that compact companion in MWC560 ejects matter in two different regimes - discrete and quasi-stationary. It is supposed that the permanent presence of a relatively weak and small-shifted Balmer absorption component in the spectrum, indicates additional persistent, not spherically symmetric matter outflow.
- ID:
- ivo://CDS.VizieR/J/A+AS/136/95
- Title:
- V380 Ori emission line spectrum
- Short Name:
- J/A+AS/136/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 3 presents the emission line spectrum of V380 Ori in the optical region observed at OHP in January 1995 with a mean resolution of 10000. For the line blends the wavelength and flux (not reddening corrected) of each contributor are given. For the P-Cygni profiles the equivalent widths of the absorption component are also reported. We estimate an error of less than 10% for the strongest lines, 10% to 40% for the weakest lines.
