- 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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- 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://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.
- ID:
- ivo://CDS.VizieR/J/ApJ/840/81
- Title:
- A^3^{Pi}-X^3^{Sigma}^-^ transitions of OH+
- Short Name:
- J/ApJ/840/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The OH^+^ ion is of critical importance to the chemistry in the interstellar medium and is a prerequisite for the generation of more complex chemical species. Submillimeter and ultraviolet observations rely on high quality laboratory spectra. Recent measurements of the fundamental vibrational band and previously unanalyzed Fourier transform spectra of the near-ultraviolet A^3^{Pi}-X^3^{Sigma}^-^ electronic spectrum, acquired at the National Solar Observatory (NSO) at Kitt Peak in 1989, provide an excellent opportunity to perform a global fit of the available data. These new optical data are approximately four times more precise as compared to the previous values. The fit to the new data provides updated molecular constants, which are necessary to predict the OH^+^ transition frequencies accurately to support future observations. These new constants are the first published using the modern effective Hamiltonian for a linear molecule. These new molecular constants allow for easy simulation of transition frequencies and spectra using the PGOPHER program. The new constants improve simulations of higher J-value infrared transitions, and represent an improvement of an order of magnitude for some constants pertaining to the optical transitions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/431
- Title:
- A planetary-mass companion to a solar-type star
- Short Name:
- J/MNRAS/492/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Young Suns Exoplanet Survey (YSES) consists of a homogeneous sample of 70 young, solar-mass stars located in the Lower Centaurus-Crux subgroup of the Scorpius-Centaurus association with an average age of 15+/-3Myr. We report the detection of a co-moving companion around the K3IV star TYC 8998-760-1 (2MASSJ13251211-6456207) that is located at a distance of 94.6+/-0.3pc using SPHERE/IRDIS on the VLT. Spectroscopic observations with VLT/X-SHOOTER constrain the mass of the star to 1.00+/-0.02M_{sun}_ and an age of 16.7+/-1.4Myr. The companion TYC 8998-760-1 b is detected at a projected separation of 1.71arcsec, which implies a projected physical separation of 162au. Photometric measurements ranging from Y to M band provide a mass estimate of 14+/-3M_Jup_ by comparison to BT-Settl and AMES-dusty isochrones, corresponding to a mass ratio of q=0.013+/-0.003 with respect to the primary. We rule out additional companions to TYC 8998-760-1 that are more massive than 12M_Jup_ and farther than 12au away from the host. Future polarimetric and spectroscopic observations of this system with ground and space based observatories will facilitate testing of formation and evolution scenarios shaping the architecture of the circumstellar environment around this 'young Sun'.
- ID:
- ivo://CDS.VizieR/J/MNRAS/269/151
- Title:
- APM cluster redshift survey
- Short Name:
- J/MNRAS/269/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present redshifts for a sample of 228 clusters selected from the APM Galaxy Survey, 188 of which are new redshift determinations. Redshifts are listed for 365 galaxies, and non-cluster galaxy redshifts have been rejected from this sample using a likelihood ratio test based on the projected and apparent magnitude distributions of each cluster region. We test this technique using clusters for which redshifts have been measured for more than 10 galaxies. Our redshift sample is nearly complete and has been used in previous papers to study the three-dimensional distribution of rich clusters of galaxies. 156 of the clusters in our sample are listed in the Abell catalogue or supplement, and the remainder are new cluster identifications.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A30
- Title:
- APM 08279+5255 CO(4-3) spectrum
- Short Name:
- J/A+A/608/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a high sensitivity observation of the UFO/BAL quasar APM 08279+5255 at z=3.912 with NOEMA at 3.2mm, aimed at detecting fast moving molecular gas. We report the detection of blueshifted CO(4-3) with maximum velocity (v95%) of -1340km/s, with respect to the systemic peak emission, and a luminosity of L'=9.9x10^9^{mu}^-1^K.km/s/pc^2^, where {mu} is the lensing magnification factor. We discuss various scenarios for the nature of this emission and conclude that this is the first detection of fast molecular gas at redshift >3. We derived a mass flow rate of molecular gas in the range dM/dt=3-7.4x10^3^M_{sun}_/yr and momentum boost (dP_OF_/dt)/(dP_AGN_/dt)~2-6, which is therefore consistent with a momentum conserving flow. For the largest dP_OF_ the scaling is also consistent with an energy conserving flow with an efficiency of ~10-20%. The present data can hardly discriminate between the two expansion modes. The mass loading factor of the molecular outflow {eta}=(dM_OF_/dt)/SFR is >>1. We also detected a molecular emission line at a frequency of 94.83GHz corresponding to a rest-frame frequency of 465.8GHz; we tentatively identified this frequency with the cation molecule N_2_H^+^(5-4), which would be the first detection of this species at high redshift. We discuss the alternative possibility that this emission is due to a CO emission line from the, so far undetected, lens galaxy. Further observations of additional transitions of the same species with NOEMA can discriminate between the two scenarios.
