- ID:
- ivo://CDS.VizieR/J/A+A/627/A6
- Title:
- APEX spectra of Centaurus A
- Short Name:
- J/A+A/627/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 5128 (Centaurus A) is one of the best targets to study AGN-feedback in the local Universe. Optical filaments located at 16 kpc from the galaxy along the radio jet direction show recent star formation, likely triggered by the interaction of the jet with an HI shell. A large reservoir of molecular gas has been discovered outside the HI. In this reservoir, lies the Horseshoe complex: a filamentary structure seen in CO with ALMA and in Halpha with MUSE. The ionised gas is mostly excited by shocks, with only a minor contribution of star formation. We used the Atacama Pathfinder EXperiment (APEX) to observe the ^12^CO(3-2) and ^12^CO(4-3) transitions, as well as dense gas tracers in the Horseshoe complex. ^12^CO(3-2) and ^12^CO(4-3) are detected for the first time in the northern filaments of Centaurus A, with integrated intensity line ratios R32~0.2 and R43~0.1, compared to the ^12^CO(1-0) emission. We also derived a line ratio R21~0.6, based on the previous ^12^CO(2-1) observations of Salome et al. (2016, Cat. J/A+A/595/A65). We used the non-LTE radiative transfer code RADEX and determined that the molecular gas in this region has a temperature of 55-70K and densities between 2-6x10^2^cm^-3^. Such densities are also in agreement with results from the Paris-Durham shock code that predicts a post-shock density of a few 100cm^-3^. However, we need more observations of emission lines at a better angular resolution in order to place tighter constraints on our radiative models, whether they are used as a stand-alone tool (LVG codes) or combined with a shock model.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/595/A65
- Title:
- APEX spectra of Centaurus A
- Short Name:
- J/A+A/595/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 5128 (Centaurus A) is one of the best example to study AGN-feedback in the local Universe. At 13.5kpc from the galaxy, optical filaments with recent star formation are lying along the radio-jet direction. We used the Atacama Pathfinder EXperiment (APEX) to map the CO(2-1) emission all along the filaments structure. Molecular gas mass of 8.2x10^7M_{sun}_ was found over the 4.2kpc-structure which represents about 3% of the total gas mass of the NGC 5128 cold gas content. Two dusty mostly molecular structures are identified, following the optical filaments. The region corresponds to the crossing of the radio jet with the northern HI shell, coming from a past galaxy merger. One filament is located at the border of the HI shell, while the other is entirely molecular, and devoid of HI gas. The molecular mass is comparable to the HI mass in the shell, suggesting a scenario where the atomic gas was shocked and transformed in molecular clouds by the radio jet. Comparison with combined FIR Herschel and UV GALEX estimation of star formation rates in the same regions leads to depletion times of more than 10 Gyr. The filaments are thus less efficient than discs in converting molecular gas into stars. Kinetic energy injection triggered by shocks all along the jet/gas interface is a possible process that appears to be consistent with MUSE line ratio diagnostics derived in a smaller region of the northern filaments. Whether the AGN is the sole origin of this energy input and what is the dominant (mechanical vs radiative) mode for this process is however still to be investigated.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A49
- Title:
- APEX spectra of massive YSOs
- Short Name:
- J/A+A/570/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Molecular outflows are a direct consequence of accretion, and therefore they represent one of the best tracers of accretion processes in the still poorly understood early phases of high-mass star formation. Previous studies suggested that the SiO abundance decreases with the evolution of a massive young stellar object probably because of a decay of jet activity, as witnessed in low-mass star-forming regions. We investigate the SiO excitation conditions and its abundance in outflows from a sample of massive young stellar objects through observations of the SiO(8-7) and CO(4-3) lines with the APEX telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A8
- Title:
- APEX spectrum of R Dor (159.0-368.5GHz)
- Short Name:
- J/A+A/615/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our current insights into the circumstellar chemistry of asymptotic giant branch (AGB) stars are largely based on studies of carbon-rich stars and stars with high mass-loss rates. In order to expand the current molecular inventory of evolved stars we present a spectral scan of the nearby, oxygen-rich star R Dor, a star with a low mass-loss rate (~2x10^-7^M_{sun}_/yr). We carried out a spectral scan in the frequency ranges 159.0-321.5GHz and 338.5-368.5GHz (wavelength range 0.8-1.9mm) using the SEPIA/Band-5 and SHeFI instruments on the APEX telescope and we compare it to previous surveys, including one of the oxygen-rich AGB star IK Tau, which has a high mass-loss rate (~5x10^-6^M_{sun}_/yr). The spectrum of R Dor is dominated by emission lines of SO_2_ and the different isotopologues of SiO. We also detect CO, H_2_O, HCN, CN, PO, PN, SO, and tentatively TiO_2_, AlO, and NaCl. Sixteen out of approximately 320 spectral features remain unidentified. Among these is a strong but previously unknown maser at 354.2GHz, which we suggest could pertain to H_2_SiO, silanone. With the exception of one, none of these unidentified lines are found in a similarly sensitive survey of IK Tau performed with the IRAM 30 m telescope. We present radiative transfer models for five isotopologues of SiO (^28^SiO, ^29^SiO, ^30^SiO, Si^17^O, Si^18^O), providing constraints on their fractional abundance and radial extent. We derive isotopic ratios for C, O, Si, and S and estimate that, based on our results for ^17^O/^18^O, R Dor likely had an initial mass in the range 1.3-1.6M_{sun}_, in agreement with earlier findings based on models of H_2_O line emission. From the presence of spectral features recurring in many of the measured thermal and maser emission lines we tentatively identify up to five kinematical components in the outflow of R Dor, indicating deviations from a smooth, spherical wind.
- ID:
- ivo://CDS.VizieR/J/AJ/162/211
- Title:
- APF radial velocity follow up of {iota} Draconis
- Short Name:
- J/AJ/162/211
- Date:
- 14 Mar 2022 06:38:23
- Publisher:
- CDS
- Description:
- Giant stars as known exoplanet hosts are relatively rare due to the potential challenges in acquiring precision radial velocities and the small predicted transit depths. However, these giant host stars are also some of the brightest in the sky and so enable high signal-to-noise ratio follow-up measurements. Here, we report on new observations of the bright (V~3.3) giant star {iota}Draconis ({iota}Dra), known to host a planet in a highly eccentric ~511 day period orbit. TESS observations of the star over 137days reveal asteroseismic signatures, allowing us to constrain the stellar radius, mass, and age to ~2%, ~6%, and ~28%, respectively. We present the results of continued radial-velocity monitoring of the star using the Automated Planet Finder over several orbits of the planet. We provide more precise planet parameters of the known planet and, through the combination of our radial-velocity measurements with Hipparcos and Gaia astrometry, we discover an additional long-period companion with an orbital period of ~68_-36_^+60^yr. Mass predictions from our analysis place this substellar companion on the border of the planet and brown dwarf regimes. The bright nature of the star combined with the revised orbital architecture of the system provides an opportunity to study planetary orbital dynamics that evolve as the star moves into the giant phase of its evolution.
- ID:
- ivo://org.gavo.dc/apfs/res/apfs_new/gdr3query
- Title:
- APFS Gaia DR3 Simple Query
- Short Name:
- apfs_gaiaquery
- Date:
- 27 Dec 2024 08:31:02
- Publisher:
- The GAVO DC team
- Description:
- This service is an extension of the Apparent Places of Fundamental Stars (APFS) computing exact geocentric positions in both the CIO and equinox systems to stars from the Gaia DR3 result catalogue.
- ID:
- ivo://org.gavo.dc/apfs/res/apfs_new/gdr2query
- Title:
- APFS Gaia DR2 Simple Query
- Short Name:
- apfs_gaiaquery
- Date:
- 27 Dec 2024 08:31:02
- Publisher:
- The GAVO DC team
- Description:
- This service is an extension of the Apparent Places of Fundamental Stars (APFS) computing exact geocentric positions in both the CIO and equinox systems to stars from the Gaia DR2 result catalogue.
1098. APFS HIP Simple Query
- ID:
- ivo://org.gavo.dc/apfs/res/apfs_new/hipquery
- Title:
- APFS HIP Simple Query
- Short Name:
- apfs_hipquery
- Date:
- 27 Dec 2024 08:31:02
- Publisher:
- The GAVO DC team
- Description:
- This service is an extension of the Apparent Places of Fundamental Stars (APFS) computing exact geocentric positions in both the CIO and equinox systems to stars from the Hipparcos catalogue.
1099. APFS Simple Query Form
- ID:
- ivo://org.gavo.dc/apfs/res/apfs_new/catquery
- Title:
- APFS Simple Query Form
- Short Name:
- apfs_catquery
- Date:
- 27 Dec 2024 08:31:02
- Publisher:
- The GAVO DC team
- Description:
- The Apparent Places of Fundamental Stars (APFS) give exact geocentric positions for a selected set of FK6 stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/19
- Title:
- A^1^{Pi}-X^1^{Sigma}^+^ transitions of CO study
- Short Name:
- J/ApJ/859/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Highly correlated ab initio calculations were performed for an accurate determination of the A^1^{Pi}-X^1^{Sigma}^+^ system of the CO molecule. A highly accurate multi-reference configuration interaction approach was used to investigate the potential energy curves (PECs) and the transition dipole moment curve (TDMC). The resultant PECs and TDMC found by using the aug-cc-pV5Z (aV5Z) basis set and 5330 active spaces are in good agreement with the experimental data. Moreover, the Einstein A coefficients, lifetimes, ro-vibrational intensities, absorption oscillator strengths, and integrated cross sections are calculated so that the vibrational bands include v"=0-39 -> v'=0-23. For applications in the atmosphere and interstellar clouds, we studied the transition lineshapes to Gaussian and Lorentzian profiles at different temperatures and pressures. The intensities were calculated at high temperature that was used to satisfy some astrophysical applications, such as in planetary atmospheres. The results are potentially useful for important SAO/NASA Astrophysics Data System and databases such as HITRAN, HITEMP, and the National Institute of Standards and Technology. Because the results from many laboratory techniques and our calculations now agree, analyses of interstellar CO based on absorption from A^1^{Pi}-X^1^{Sigma}^+^ are no longer hindered by present spectral parameters.
