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- ID:
- ivo://CDS.VizieR/J/ApJ/904/14
- Title:
- Optical and NIR observation of SN (Ia) 2017cbv
- Short Name:
- J/ApJ/904/14
- Date:
- 24 Mar 2022 06:19:55
- Publisher:
- CDS
- Description:
- Supernova (SN) 2017cbv in NGC5643 is one of a handful of Type Ia supernovae (SNeIa) reported to have excess blue emission at early times. This paper presents extensive BVRIYJHKs-band light curves of SN2017cbv, covering the phase from -16 to +125days relative to B-band maximum light. The SN2017cbv reached a B-band maximum of 11.710{+/-}0.006mag, with a postmaximum magnitude decline of {Delta}m15(B)=0.990{+/-}0.013mag. The SN suffered no host reddening based on Phillips intrinsic color, the Lira-Phillips relation, and the CMAGIC diagram. By employing the CMAGIC distance modulus {mu}=30.58{+/-}0.05mag and assuming H0=72km/s/Mpc, we found that 0.73M{sun} 56Ni was synthesized during the explosion of SN2017cbv, which is consistent with estimates using reddening- and distance-free methods via the phases of the secondary maximum of the near-IR- (NIR-) band light curves. We also present 14 NIR spectra from -18 to +49 days relative to the B-band maximum light, providing constraints on the amount of swept-up hydrogen from the companion star in the context of the single degenerate progenitor scenario. No Pa{beta} emission feature was detected from our postmaximum NIR spectra, placing a hydrogen mass upper limit of 0.1M{sun}. The overall optical/NIR photometric and NIR spectral evolution of SN2017cbv is similar to that of a normal SN Ia, even though its early evolution is marked by a flux excess not seen in most other well-observed normal SNe Ia. We also compare the exquisite light curves of SN2017cbv with some Mch delayed detonation models and sub-Mch double detonation models.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A82
- Title:
- Quasar 3C 345 at 18 cm with RadioAstron
- Short Name:
- J/A+A/648/A82
- Date:
- 23 Mar 2022 16:32:52
- Publisher:
- CDS
- Description:
- Supermassive black holes in the centres of radio-loud active galactic nuclei (AGN) can produce collimated relativistic outflows (jets). Magnetic fields are thought to play a key role in the formation and collimation of these jets, but the details are much debated. We study the innermost jet morphology and magnetic field strength in the AGN 3C 345 with an unprecedented resolution using images obtained within the framework of the key science programme on AGN polarisation of the Space VLBI mission RadioAstron. We observed the flat spectrum radio quasar 3C 345 at 1.6GHz on 2016 March 30 with RadioAstron and 18 ground-based radio telescopes in full polarisation mode. Our images, in both total intensity and linear polarisation, reveal a complex jet structure at 300{mu}as as angular resolution, corresponding to a projected linear scale of about 2pc or a few thousand gravitational radii. We identify the synchrotron self-absorbed core at the jet base and find the brightest feature in the jet 1.5 mas downstream of the core. Several polarised components appear in the Space VLBI images that cannot be seen from ground array-only images. Except for the core, the electric vector position angles follow the local jet direction, suggesting a magnetic field perpendicular to the jet. This indicates the presence of plane perpendicular shocks in these regions. Additionally, we infer a minimum brightness temperature at the largest uv-distances of 1.1x10^12^K in the source frame, which is above the inverse Compton limit and an order of magnitude larger than the equipartition value. This indicates locally efficient injection or re-acceleration of particles in the jet to counter the inverse Compton cooling or the geometry of the jet creates significant changes in the Doppler factor, which has to be >11 to explain the high brightness temperatures.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A18
- Title:
- The Bok globule CB 26
- Short Name:
- J/A+A/646/A18
- Date:
- 23 Mar 2022 16:32:20
- Publisher:
- CDS
- Description:
- Planetary cores are thought to form in proto-planetary disks via the growth of dusty solid material. However, it is unclear how early this process begins. We study the physical structure and grain growth in the edge-on disk that surrounds the ~1Myr old low-mass (~0.55M_{sun}_) protostar embedded in the Bok Globule CB26 to examine how much grain growth has already occurred in the protostellar phase. We combine the SED between 0.9um and 6.4cm with high angular resolution continuum maps at 1.3, 2.9, and 8.1mm, and use the radiative transfer code RADMC-3D to conduct a detailed modelling of the dust emission from the disk and envelope of CB 26. We infer inner and outer disk radii of around 16au and 172+/-22au, respectively. The total gas mass in the disk is ~0.076M_{sun}_, which amounts to ~14% of the mass of the central star. The inner disk contains a compact free-free emission region, which could be related to either a jet or a photoevaporation region. The thermal dust emission from the outer disk is optically thin at mm wavelengths, while the emission from the inner disk midplane is moderately optically thick. Our best-fit radiative transfer models indicate that the dust grains in the disk have already grown to pebbles with diameters of the order of 10cm in size. Residual 8.1mm emission suggests the presence of even larger particles in the inner disk. For the optically thin mm dust emission from the outer disk, we derive a mean opacity slope of {beta}_mm_~=0.7+/-0.4, which is consistent with the presence of large dust grains. The presence of cm-sized bodies in the CB 26 disk indicates that solids grow rapidly already during the first million years in a protostellar disk. It is thus possible that Class II disks are already seeded with large particles and may contain even planetesimals.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A20
- Title:
- W Aql APEX spectrum
- Short Name:
- J/A+A/642/A20
- Date:
- 23 Mar 2022 16:31:40
- Publisher:
- CDS
- Description:
- W Aql is an asymptotic giant branch (AGB) star with an atmospheric elemental abundance ratio C/O~=0.98. It has previously been reported to have circumstellar molecular abundances intermediate between those of M-type and C-type AGB stars, which respectively have C/O<1 and C/O>1. This intermediate status is considered typical for S-type stars, although our understanding of the chemical content of their circumstellar envelopes is currently rather limited. We wish to assess the reported intermediate status of W Aql by analysing the line emission of molecules that have not been observed towards this star before. We have performed observations in the frequency range 159-268GHz with the SEPIA/B5 and PI230 instruments on the APEX telescope. We make abundance estimates through direct comparison to available spectra towards a number of well-studied AGB stars and based on rotational diagram analysis in the case of one molecule. From a compilation of our abundance estimates and those found in the literature for two M-type (R Dor, IK Tau), two S-type ({chi} Cyg, W Aql), and two C-type stars (V Aql, IRC +10 216), we conclude that W Aql's circumstellar environment appears considerably closer to that of a C-type AGB star than to that of an M-type AGB star. In particular, we detect emission from C_2_H, SiC_2_, SiN, and HC_3_N, molecules previously only detected towards the circumstellar environment of C-type stars. This conclusion, based on the chemistry of the gaseous component of the circumstellar environment, is further supported by reports in the literature on the presence of atmospheric molecular bands and spectral features of dust species which are typical for C-type AGB stars. Although our observations mainly trace species in the outer regions of the circumstellar environment, our conclusion matches closely that based on recent chemical equilibrium models for the inner wind of S-type stars: the atmospheric and circumstellar chemistry of S-type stars likely resembles that of C-type AGB stars much more closely than that of M-type AGB stars. Further observational investigation of the gaseous circumstellar chemistry of S-type stars is required to characterise its dependence on the atmospheric C/O. Non-equilibrium chemical models of the circumstellar environment of AGB stars need to address the particular class of S-type stars and the chemical variety that is induced by the range in atmospheric C/O.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A47
- Title:
- SPHERE and NaCo images of HD 19467B
- Short Name:
- J/A+A/639/A47
- Date:
- 23 Mar 2022 16:31:06
- Publisher:
- CDS
- Description:
- HD 19467 observations were performed with the VLT exoplanet imager SPHERE and the VLT adaptive optics camera NaCo to further characterize the spectral and orbital properties of the known T-type brown dwarf companion.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A121
- Title:
- LkCa 15 and 2MASS J16100501-2132318 ALMa images
- Short Name:
- J/A+A/639/A121
- Date:
- 23 Mar 2022 16:30:37
- Publisher:
- CDS
- Description:
- We present high-resolution millimeter continuum ALMA observations of the disks around the T Tauri stars LkCa 15 and 2MASS J16100501-2132318 (hereafter, J1610). These transition disks host dust-depleted inner regions, which have possibly been carved by massive planets, and they are of prime interest to the study of the imprints of planet-disk interactions. While at moderate angular resolution, they appear as a broad ring surrounding a cavity, the continuum emission resolves into multiple rings at a resolution of ~60x40,mas (~7.5au for LkCa 15, ~6au for J1610) and ~7uJy/beam rms at 1.3mm. In addition to a broad extended component, LkCa 15 and J1610 host three and two narrow rings, respectively, with two bright rings in LkCa 15 being radially resolved. LkCa 15 possibly hosts another faint ring close to the outer edge of the mm emission. The rings look marginally optically thick, with peak optical depths of ~0.5 (neglecting scattering), in agreement with high angular resolution observations of full disks. We performed hydrodynamical simulations with an embedded, sub-Jovian-mass planet and show that the observed multi-ringed substructure can be qualitatively explained as the outcome of the planet-disk interaction. We note, however, that the choice of the disk cooling timescale alone can significantly impact the resulting gas and dust distributions around the planet, leading to different numbers of rings and gaps and different spacings between them. We propose that the massive outer disk regions of transition disks are favorable places for planetesimals, and possibly second-generation planet formation of objects with a lower mass than the planets carving the inner cavity (typically few M_Jup_), and that the annular substructures observed in LkCa~15 and J1610 may be indicative of planetary core formation within dust-rich pressure traps. Current observations are compatible with other mechanisms contributing to the origin of the observed substructures, in particular with regard to narrow rings generated (or facilitated) at the edge of the CO and N_2_ snowlines.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A29
- Title:
- 3C388 145, 392, 614, 1400 and 4850MHz images
- Short Name:
- J/A+A/638/A29
- Date:
- 23 Mar 2022 16:29:17
- Publisher:
- CDS
- Description:
- Restarted radio galaxies represent a unique tool to investigate the duty cycle of the jet activity in Active Galactic Nuclei. Due to a sharp discontinuity of the GHz spectral index distribution within its lobes, the radio galaxy 3C388 has for long being claimed to be a peculiar example of AGN with multi-epoch activity The goal of this work is to perform for the first time a spatially resolved study of the radio spectrum of this source down to MHz-frequencies, in order to investigate its radiative age and constrain its duty cycle. We have used new low frequency observations at 144MHz performed with the Low Frequency Array and at 350MHz performed with the Very Large Array combined with archival data at higher frequencies (614, 1400, 4850MHz). Results. We find that the spectral indices in the lower frequency range 144-614MHz have flatter values ({alpha}_low_~0.55-1.14) than those observed in the higher frequency range 1400-4850MHz ({alpha}_high_~0.75-1.57) but follow the same distribution across the lobes, with a systematic steepening towards the edges. However, the spectral shape throughout the source is not uniform and often deviates from standard models. This suggests that mixing of different particle populations is occurring, although it remains difficult to understand whether this is caused by observational limitations (insufficient spatial resolution and/or projection effects) or by the intrinsic presence of multiple particle populations, possibly related to the two different outbursts. By using single-injection radiative models we compute that the total source age is <~80Myr and that the duty cycle is about t_on_/t_tot_~60%, which is enough to prevent the intracluster medium from cooling according to X-ray estimates. While to date the radio spectral distribution of 3C388 remains a rare case among radio galaxies, multi-frequency surveys performed with new generation instruments will soon allow us to investigate whether more sources with the same characteristics do actually exist.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A69
- Title:
- LOFAR 143MHz images of 3C 236
- Short Name:
- J/A+A/628/A69
- Date:
- 23 Mar 2022 16:28:49
- Publisher:
- CDS
- Description:
- We have examined the giant radio galaxy 3C 236 using LOFAR at 143MHz down to an angular resolution of 7 arcseconds, in combination with observations at higher frequencies. We used the low frequency data to derive spectral index maps with the highest resolution yet at these low frequencies. We confirm a previous detection of an inner hotspot in the north-west lobe and for the first time observe that the south-east lobe hotspot is in fact a triple hotspot, which may point to an intermittent source activity. Also, the spectral index map of 3C 236 shows that the spectral steepening at the inner region of the northern lobe is prominent at low frequencies. The outer regions of both lobes show spectral flattening, in contrast with previous high frequency studies. We derive spectral age estimates for the lobes, as well as particle densities of the IGM at various locations. We propose that the morphological differences between the lobes are driven by variations in the ambient medium density as well as the source activity history.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A94
- Title:
- FS Tau B two epoch spectro-imagery
- Short Name:
- J/A+A/627/A94
- Date:
- 23 Mar 2022 16:28:17
- Publisher:
- CDS
- Description:
- Herbig-Haro (HH) flows exhibit a large variety of morphological and kinematical structures such as bow shocks, Mach disks, and deflection shocks. Both proper motion (PM) and radial velocity investigations are essential to understand the physical nature of such structures. We investigate the kinematics and PM of spectrally separated structures in the FS Tau B HH flow. Collating these data makes it possible to understand the origin of these structures and to explain the unusual behavior of the jet. On the other hand, the study of emission profiles in the associated reflection nebulae allows us to consider the source of the outflow both from edge-on and pole-on points of view. We present the observational results obtained with the 6 m telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences using the SCORPIO multimode focal reducer with a scanning Fabry-Perot interferometer. Two epochs of the observations of the FS Tau B region in H{alpha} emission (2001 and 2012) allowed us to measure the PM of the spectrally separated inner structures of the jet. In addition to already known emission structures in the FS Tau B system, we discover new features in the extended part of the jet and in the counter-jet. Moreover, we reveal a new HH knot in the HH 276 independent outflow system and point out its presumable source. In the terminal working surface of the jet, structures with different radial velocities have PMs of the same value. This result can be interpreted as the direct observation of bow-shock and Mach disk regions. A bar-like structure, located southwest from the source demonstrates zero PM and can be considered as one more example of deflection shock. An analysis of H{alpha} profiles in the reflection nebulae R1 and R3 indicates the uniqueness of this object, which can be studied in pole-on and edge-on directions simultaneously.