- ID:
- ivo://CDS.VizieR/J/ApJ/734/98
- Title:
- DISCS. II. Southern sky disk data
- Short Name:
- J/ApJ/734/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers based on data from DISCS, a Submillimeter Array observing program aimed at spatially and spectrally resolving the chemical composition of 12 protoplanetary disks. We present data on six Southern sky sources -IM Lup, SAO 206462 (HD 135344b), HD 142527, AS 209, AS 205, and V4046 Sgr- which complement the six sources in the Taurus star-forming region reported previously. CO 2-1 and HCO^+^ 3-2 emission are detected and resolved in all disks and show velocity patterns consistent with Keplerian rotation. Where detected, the emission from DCO^+^ 3-2, N_2_H^+^ 3-2, H_2_CO 3_0 3_-2_0 2_ and 4_1 4_-3_1 3_, HCN 3-2, and CN 2_3 3/4/2_-1_2 2/3/1_ are also generally spatially resolved. The detection rates are highest toward the M and K stars, while the F star SAO 206462 has only weak CN and HCN emission, and H2CO alone is detected toward HD 142527.
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- ID:
- ivo://CDS.VizieR/J/ApJ/720/480
- Title:
- DISCS. I. Taurus protoplanetary disk data
- Short Name:
- J/ApJ/720/480
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemistry plays an important role in the structure and evolution of protoplanetary disks, with implications for the composition of comets and planets. This is the first of a series of papers based on data from DISCS (Disk Imaging Survey of Chemistry with SMA), a Submillimeter Array survey of the chemical composition of protoplanetary disks. The six Taurus sources in the program (DM Tau, AA Tau, LkCa 15, GM Aur, CQ Tau, and MWC 480) range in stellar spectral type from M1 to A4 and offer an opportunity to test the effects of stellar luminosity on the disk chemistry. The disks were observed in 10 different lines at ~3" resolution and an rms of ~100mJy/beam at ~0.5km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A85
- Title:
- Disentangled spectra of R145
- Short Name:
- J/A+A/598/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first SB2 orbital solution and disentanglement of the massive Wolf-Rayet binary R145 (P=159d) located in the Large Magellanic Cloud. The primary was claimed to have a stellar mass greater than 300M_{sun}_, making it a candidate for the most massive star known. While the primary is a known late type, H-rich Wolf-Rayet star (WN6h), the secondary could not be so far unambiguously detected. Using moderate resolution spectra, we are able to derive accurate radial velocities for both components. By performing simultaneous orbital and polarimetric analyses, we derive the complete set of orbital parameters, including the inclination. The spectra are disentangled and spectroscopically analyzed, and an analysis of the wind-wind collision zone is conducted.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/L40
- Title:
- Disentangling cataclysmic variables in Gaia DR2
- Short Name:
- J/MNRAS/492/L40
- Date:
- 07 Dec 2021 09:36:41
- Publisher:
- CDS
- Description:
- Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram (HR-diagram). The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at G_BP_-G_RP_~=0.56 and G_abs_~10.15. We nd a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV sub-types in the HR-diagram and discuss the possible location of detached CVs, going through the orbital period gap.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/L3
- Title:
- Disilicon carbide (SiCSi) discovery in CW Leo
- Short Name:
- J/ApJ/806/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery in space of a disilicon species, SiCSi, from observations between 80 and 350GHz with the IRAM 30m radio telescope. Owing to the close coordination between laboratory experiments and astrophysics, 112 lines have now been detected in the carbon-rich star CW Leo. The derived frequencies yield improved rotational and centrifugal distortion constants up to sixth order. From the line profiles and interferometric maps with the Submillimeter Array, the bulk of the SiCSi emission arises from a region of 6" in radius. The derived abundance is comparable to that of SiC_2_. As expected from chemical equilibrium calculations, SiCSi and SiC_2_ are the most abundant species harboring a Si-C bond in the dust formation zone and certainly both play a key role in the formation of SiC dust grains.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A104
- Title:
- Disk and halo stars C, O and Fe abundances
- Short Name:
- J/A+A/630/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundances of carbon, oxygen, and iron in late-type stars are important parameters in exoplanetary and stellar physics, as well as key tracers of stellar populations and Galactic chemical evolution. However, standard spectroscopic abundance analyses can be prone to severe systematic errors, by the assumption that the stellar atmosphere is one-dimensional (1D) and hydrostatic, and by ignoring departures from local thermodynamic equilibrium (LTE). To address this, we carry out 3D non-LTE radiative transfer calculations for CI and OI, and 3D LTE radiative transfer calculations for FeII, across the stagger-grid of 3D hydrodynamic model atmospheres. The absolute 3D non-LTE versus 1D LTE abundance corrections can be as severe as ~0.3dex for CI lines in low-metallicity F dwarfs, and ~0.6dex for OI lines in high-metallicity F dwarfs. The 3D LTE versus 1D LTE abundance corrections for FeII lines are less severe, typically less than +0.15dex. We use the corrections in a re-analysis of carbon, oxygen, and iron in 187 F and G dwarfs in the Galactic disk and halo. Applying the differential 3D non-LTE corrections to 1D LTE abundances visibly reduces the scatter in the abundance plots. The thick disk and high- halo population rise in carbon and oxygen with decreasing metallicity, reaching a maximum of [C/Fe]~=0.2 and a plateau of [O/Fe]~=0.6 at [Fe/H]~=~1.0. The low- halo population is qualitatively similar, albeit offset towards lower metallicities and with larger scatter. Nevertheless, these populations overlap in the [C/O] versus [O/H] plane, decreasing to a plateau of [C/O]~=0.6 below [O/H]~=1.0. In the thin-disk, stars having confirmed planet detections tend to have higher values of C/O at given [O/H]; this potential signature of planet formation is only apparent after applying the abundance corrections to the 1D LTE results. Our grids of line-by-line abundance corrections are publicly available and can readily be used to improve the accuracy of spectroscopic analyses of late-type stars.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A149
- Title:
- Disk and halo stars C, O and Fe abundances (Amarsi+, 2019)
- Short Name:
- J/A+A/630/A149
- Date:
- 27 Sep 2019 05:42:26
- Publisher:
- CDS
- Description:
- Spectrum synthesis calculations were performed on four different families of model atmospheres: 3D hydrodynamic model atmospheres from the STAGGER-grid (Magic et al. 2013A&A...557A..26M, Cat. J/A+A/557/A26); 1D model atmospheres determined by averaging the <3D> STAGGER model atmospheres (henceforth <3D> model atmospheres; Magic et al. 2013A&A...560A...8M, Cat. J/A+A/560/A8); theoretical 1D hydrostatic model atmospheres from the ATMO-grid (the 1D equivalent of the STAGGER-grid, see Appendix A of Magic et al. 2013A&A...557A..26M, Cat. J/A+A/557/A26); and theoretical 1D hydrostatic model atmospheres from the MARCS-grid (Gustafsson et al. 2008A&A...486..951G). Table1 contains the line parameters that were adopted for the grids of abundance corrections. Table2 contains the 3D non-LTE versus 1D LTE abundance corrections for CI lines. Table3 contains the 3D non-LTE versus 1D LTE abundance corrections for OI lines. Table4 contains the 3D LTE versus 1D LTE abundance corrections for FeII lines. Table5 contains the 1D non-LTE versus 1D LTE abundance corrections for CI lines. Table6 contains the 1D non-LTE versus 1D LTE abundance corrections for OI lines. Table7 contains the stellar parameters and abundances for the 187 sample stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/773/135
- Title:
- Disk-bearing stars in Cygnus OB2
- Short Name:
- J/ApJ/773/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of stars in massive clusters is one of the main modes of the star formation process. However, the study of massive star-forming regions is hampered by their typically large distances to the Sun. One exception to this is the massive star-forming region Cygnus OB2 in the Cygnus X region, at the distance of ~1400pc. Cygnus OB2 hosts very rich populations of massive and low-mass stars, being the best target in our Galaxy to study the formation of stars, circumstellar disks, and planets in the presence of massive stars. In this paper, we combine a wide and deep set of photometric data, from the r band to 24{mu}m, in order to select the disk-bearing population of stars in Cygnus OB2 and identify the class I, class II, and stars with transition and pre-transition disks. We selected 1843 sources with infrared excesses in an area of 1{deg}x1{deg} centered on Cyg OB2 in several evolutionary stages: 8.4% class I, 13.1% flat-spectrum sources, 72.9% class II, 2.3% pre-transition disks, and 3.3% transition disks. The spatial distribution of these sources shows a central cluster surrounded by an annular overdensity and some clumps of recent star formation in the outer region. Several candidate subclusters are identified, both along the overdensity and in the rest of the association.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2085
- Title:
- Disk brightness profiles in galaxies
- Short Name:
- J/AJ/127/2085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the disk brightness profiles of 218 spiral and lenticular galaxies. At least 28% of disk galaxies exhibit inner truncations in these profiles. There are no significant trends of truncation incidence with Hubble type, but the incidence among barred systems is 49%, more than 4 times that for non-barred galaxies. However, not all barred systems have inner truncations, and not all inner-truncated systems are currently barred. Truncations represent a real dearth of disk stars in the inner regions and are not an artifact of our selection or fitting procedures nor the result of obscuration by dust.
- ID:
- ivo://CDS.VizieR/J/ApJ/688/237
- Title:
- Disk corrugations in IC 2233
- Short Name:
- J/ApJ/688/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We recently reported the discovery of a regular corrugation pattern in the HI disk of the isolated, edge-on spiral galaxy IC 2233. Here we present measurements of the vertical structure of this galaxy at several additional wavelengths, ranging from the far-ultraviolet to the far-infrared. We find that undular patterns with amplitude <~5"(<~250pc) are visible in a variety of Population I tracers in IC 2233, including the young to intermediate-age stars, the HII regions, and the dust. However, the vertical excursions become less pronounced in the older stellar populations traced by the mid-infrared light. This suggests that the process leading to the vertical displacements may be linked with the regulation of star formation in the galaxy. We have also identified a relationship between the locations of the density corrugations and small-amplitude (<~5km/s) velocity undulations in the HI rotation curve. We are able to exclude several possible mechanisms for the origin of the observed corrugations, including tidal interaction from a companion, Parker instabilities, or a galactic bore. Global gravitational instabilities appear to be the most likely explanation, although local perturbations may also be important.