- ID:
- ivo://CDS.VizieR/J/A+A/646/A178
- Title:
- Spectra of 2 z>3 hot dust-obscured galaxies
- Short Name:
- J/A+A/646/A178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present the detection of H_2_O and OH+ emission in z>3 hot dust-obscured galaxies (Hot DOGs). Using ALMA Band-6 observations of two Hot DOGs, we have detected H_2_O(2_02_-1_11_) in W0149+2350, and H_2_O(3_12_-3_03_) and the multiplet OH+(1_1-0_1) in W0410-0913. These detections were serendipitous, falling within the side-bands of Band-6 observations aimed to study CO(9-8) in these Hot DOGs. We find that both sources have luminous H_2_O emission with line luminosities of L_H2O_>2.2x10^8^L_{sun}_ and L_H2O_=8.7x10^8^L_{sun}_ for W0149+2350 and W0410-0913, respectively. The H_2_O line profiles are similar to those seen for the neighbouring CO(9-8) line, with linewidths of FWHM~800-1000km/s. However, the H_2_O emission seems to be more compact than the CO(9-8). OH+ is detected in emission for W0410-0913, with a FWHM=1000km/s and a line luminosity of L_OH+_=6.92x10^8^L_{sun}_. The ratio of the observed H_2_O line luminosity over the IR luminosity, for both Hot DOGs, is consistent with previously observed star forming galaxies and AGN. The H_2_O/CO line ratio of both Hot DOGs and the OH+/H_2_O line ratio of W0410-0913 are comparable to those of luminous AGN in the literature. The bright H_2_O(2_02_-1_11_), and H_2_O(3_12_-3_03_) emission lines are likely due to the combined high star formation levels and luminous AGN in these sources. The presence of OH+ in emission, and the agreement of the observed line ratios of the Hot DOGs with luminous AGN in the literature, would suggest that the AGN emission is dominating the radiative output of these galaxies. However, followup multi-transition observations are needed to better constrain the properties of these systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1925
- Title:
- Spectrocopic Binarity of O and B type stars
- Short Name:
- J/MNRAS/424/1925
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of stars above about 20M_{sun}_ and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and 540 B-type stars in the southern Milky Way which indicates that the majority of stars (>82%) with masses above 16M_{sun}_ form close binary systems while this fraction rapidly drops to 20% for stars of 3M_{sun}_. The binary fractions of O-type stars among different environment classes are: clusters (72+/-13%), associations (73+/-8%), field (43+/-13%) and runaways (69+/-11%). The high frequency of close pairs with components of similar mass argues in favour of a multiplicity originating from the formation process rather than from a tidal capture in a dense cluster. The high binary frequency of runaway O stars that we found in our survey (69% compared to 19-26% in previous surveys) points to the importance of ejection from young star clusters and thus supports the competitive accretion scenario.
- ID:
- ivo://CDS.VizieR/J/A+A/433/151
- Title:
- Spectrocopic results on ROSAT late-type stars
- Short Name:
- J/A+A/433/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an investigation of the X-ray properties, age distribution, and kinematical characteristics of a high-galactic latitude sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS). The sample comprises 254 RASS sources with optical counterparts of spectral types F to M distributed over six study areas located at |b|>~20{deg}, and Dec>=-9{deg}. A detailed study was carried out for the subsample of ~200 G, K, and M stars. Lithium abundances were determined for 179 G-M stars. Radial velocities were measured for most of the 141 G and K type stars of the sample. Combined with proper motions these data were used to study the age distribution and the kinematical properties of the sample. Based on the lithium abundances half of the G-K stars were found to be younger than the Hyades (660Myr). About 25% are comparable in age to the Pleiades (100Myr). A small subsample of 10 stars is younger than the Pleiades. They are therefore most likely pre-main sequence stars. Kinematically the PMS and Pleiades-type stars appear to form a group with space velocities close to the Castor moving group but clearly distinct from the Local Association.
- ID:
- ivo://CDS.VizieR/J/AJ/103/267
- Title:
- Spectrocopy of hot stars in galactic halo
- Short Name:
- J/AJ/103/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper presents spectroscopy for 769 hot stars from the HK objective-prism/interference-filter survey of Beers et al. (1985), 193 of which have also available broadband UBV colors. When available, photometric information is used to obtain estimates of the surface temperature for degenerates and for O- and B-type subdwarfs, based on previously derived calibrations. Several extremely hot (T(eff) greater than 50,000 K) He-rich sdO stars are identified. Out of 769 stars in this sample, 551 are clearly identified on the basis of their Balmer line profiles as field horizontal-branch (FHB) or mid-to late-type A stars. The A stars exhibit rotation and line-of-sight dispersion consistent with membership in the galactic thick disk. The FHB stars exhibit kinematic properties which suggest a transition from thick disk to halo.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/672
- Title:
- Spectrocopy of YSOs in Serpens molecular cloud
- Short Name:
- J/ApJ/691/672
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of an optical spectroscopic survey designed to confirm the youth and determine the spectral types among a sample of young stellar object (YSO) candidates in the Serpens molecular cloud. We observed 150 infrared (IR) excess objects previously discovered by the Spitzer Legacy Program "From Molecular Cores to Planet-Forming Disks" (c2d), bright enough for subsequent Spitzer/InfraRed Spectrograph (IRS) spectroscopy. We obtained 78 optical spectra of sufficient signal-to-noise for analysis. Extinctions, effective temperatures, and luminosities are estimated for this sample, and used to construct Hertzsprung-Russell (H-R) diagrams for the population. We identified 20 background giants contaminating the sample, based on their relatively high extinction, position in the H-R diagram, the lack of H{alpha} emission and relatively low IR excess. Such strong background contamination (25%) is consistent with the location of Serpens being close to the Galactic plane (5{deg} Galactic latitude). The remaining 58 stars (75%) were all confirmed to be young, mostly K- and M-type stars that are presumed to belong to the cloud. Our analysis shows that the majority of the IR excess objects detected in Serpens are actively accreting, young T-Tauri stars.
- ID:
- ivo://CDS.VizieR/J/A+A/285/1
- Title:
- Spectrographic study of Kiso UV-excess galaxies
- Short Name:
- J/A+A/285/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/621/A6
- Title:
- Spectro-interferometric observation of SW Vir
- Short Name:
- J/A+A/621/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared spectro-interferometric observation of the non-Mira-type, semiregular asymptotic giant branch star SW Vir. Our aim is to probe the physical properties of the outer atmosphere with spatially resolved data in individual molecular and atomic lines. We observed SW Vir in the spectral window between 2.28 and 2.31 micron with the near-infrared interferometric instrument AMBER at ESO's Very Large Telescope Interferometer (VLTI). Thanks to AMBER's high spatial resolution and high spectral resolution of 12000, the atmosphere of SW Vir has been spatially resolved not only in strong CO first overtone lines but also in weak molecular and atomic lines of H_2_O, CN, HF, Ti, Fe, Mg, and Ca. While the uniform-disk diameter of the star is 16.23+/-0.20mas in the continuum, it increases up to 22-24mas in the CO lines. Comparison with the MARCS photospheric models reveals that the star appears larger than predicted by the hydrostatic models not only in the CO lines but also even in the weak molecular and atomic lines. We found that this is primarily due to the H2O lines (but also possibly due to the HF and Ti lines) originating in the extended outer atmosphere. Although the H_2_O lines manifest themselves very little in the spatially unresolved spectrum, the individual rovibrational H_2_O lines from the outer atmosphere can be identified in the spectro-interferometric data. Our modeling suggests an H_2_O column density of 10^19^-10^20^cm^-2^ in the outer atmosphere extending out to ~2R*. Our study has revealed that the effects of the nonphotospheric outer atmosphere are present in the spectro-interferometric data not only in the strong CO first overtone lines but also in the weak molecular and atomic lines. Therefore, analyses of spatially unresolved spectra, such as for example analyses of the chemical composition, should be carried out with care even if the lines appear to be weak.
- ID:
- ivo://CDS.VizieR/J/MNRAS/489/2595
- Title:
- Spectro-interferometry of 8 evolved stars
- Short Name:
- J/MNRAS/489/2595
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the physical parameters of the outer atmosphere of a sample of eight evolved stars, including the red supergiant {alpha} Scorpii, the red giant branch stars {alpha} Bootis and {gamma} Crucis, the K giant {lambda} Velorum, the normal M giants BK Virginis and SW Virginis, and the Mira star W Hydrae (in two different luminosity phases) by spatially resolving the stars in the individual carbon monoxide (CO) first overtone lines. We used the Astronomical Multi-BEam combineR (AMBER) instrument at the Very Large Telescope Interferometer (VLTI), in high-resolution mode ({lambda}/{Delta}{lambda}~=12000) between 2.28 and 2.31um in the K band. The maximal angular resolution is 10mas, obtained using a triplet telescope configuration, with baselines from 7 to 48m. By using a numerical model of a molecular atmosphere in a spherical shells (MOLsphere), called PAMPERO (an acronym for the 'physical approach of molecular photospheric ejection at high angular resolution for evolved stars'), we add multiple extended CO layers above the photospheric MARCS model at an adequate spatial resolution. We use the differential visibilities and the spectrum to estimate the size (R) of the CO MOLsphere, its column density (NCO) and temperature (Tmol) distributions along the stellar radius. The combining of the {chi}^2^ minimization and a fine grid approach for uncertainty analysis leads to reasonable NCO and Tmol distributions along the stellar radius of the MOLsphere.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/1398
- Title:
- Spectro. monitoring of HDE 245770 and X Per
- Short Name:
- J/ApJ/660/1398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from an H{alpha} monitoring campaign of the Be X-ray binary systems HDE 245770 = A0535+26 and X Per. We use the H{alpha} equivalent widths together with adopted values of the Be star effective temperature, disk inclination, and disk outer boundary to determine the half-maximum emission radius of the disk as a function of time.
- ID:
- ivo://CDS.VizieR/VII/141
- Title:
- Spectrophotometric Atlas of Galaxies
- Short Name:
- VII/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains 56 spectra: 55 galaxy spectra, and one night sky spectrum, which is included for users wishing to check for low-level spurious features in the galaxy spectra. The file "spectra.dat" contains a summary of the spectra. The user should consult the paper for details of the observations and a discussion of the limitations of the spectrophotometry. The spectra are integrated measurements made with apertures comparable to the diameters of the galaxies. The original spectra have been combined, rebinned to a common wavelength scale, and normalized in flux to unity at a reference wavelength of 555nm. An atmospheric extinction correction has been applied to the data, but otherwise they are not corrected for reddening, redshift, etc. The spectral range covered is 365-710 nm and the resolution is 5-8{AA}. Each spectrum consists in 1726 normalized flux values spaced each 2{AA}, stored as a file in the subdirectory "sp". Tests show that the spectrophotometry is accurate to the few percent level over small wavelength regions, and at the 10% level over the entire wavelength range. Although the data are useful for a variety of applications, the user should be forewarned that they may not be suitable for applications requiring precision colors over a long wavelength baseline (e.g., computation of K-corrections, some spectral synthesis applications).