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We present near-IR and far-UV observations of the pre-transitional (gapped)
disk in HD 169142 using NASA's Infrared Telescope Facility and Hubble Space
Telescope. The combination of our data along with existing data sets into the
broadband spectral energy distribution reveals variability of up to 45% between
~1.5-10 {\mu}m over a maximum timescale...
Context in source publication
Context 1
... 169142 was observed 3 times in the FUV in 2013 using the Hubble Space Telescope: twice by the Space Telescope Imaging Spectrograph (STIS, see Woodgate et al. 1998), and once using the Cosmic Origins Spectrograph (COS, see Green et al. 2012). Table 1 is the journal of FUV observations, augmented by archival data for Altair using the Goddard High-Resolution Spectro- graph (GHRS), which serves as a useful comparison star in the UV. All spectra were processed using the pipeline software appropriate for their date of observation (COS: Holland et al. 2014;STIS: Hernandez, S. et al. 2014;and HRS: Soderblom et al. 1995). ...
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Aims. Our goal is to determine the molecular composition of the circumstellar
disk around AB Aurigae (hereafter, AB Aur). AB Aur is a prototypical Herbig Ae
star and the understanding of its disk chemistry is of paramount importance to
understand the chemical evolution of the gas in warm disks. Methods. We used
the IRAM 30-m telescope to perform a...
Citations
... In previous work (e.g., Close et al. 2014;Sallum et al. 2015;Wagner et al. 2015b;Follette et al. 2017;Rameau et al. 2017), Hα line luminosities (L Hα ) and limits on this quantity have been computed following the equation: ...
... The mass accretion rate onto the primary star is estimated at 1.5-2.7×10 −9 M e yr −1 based on fits to the Paβ and Brγ lines obtained with SpeX on the IRTF (Wagner et al. 2015b). ...
... Salyk et al. (2013),26 Collins et al. (2009),27 Wagner et al. (2015b),28 Sitko et al. (2012),29 Willson et al. (2019),30 Curran et al. (2011), 31 Pascucci et al. (2007, 32 Andrews et al.(2011a), 33 Robinson & Espaillat (2019), 34 Manara et al. (2014), 35 Alencar et al. (2018), 36 Müller et al. (2018), 37 Thanathibodee et al. (2020) 38 Francis & van der Marel (2020), 39 Pineda et al. (2019), 40 Miley et al. (2018), 41 van der Plas et al. (2019), 42 Fedele et al. (2017), 43 Pérez et al. (2019), 44 Cazzoletti et al. (2018), 45 Kraus et al. (2017), 46 Kastner et al. (2018), 47 Pinilla et al. (2014), 48 Andrews et al. (2016), 49 Facchini et al. (2020), 50 Avenhaus et al. (2014), 51 Follette et al. (2017), 52 Konishi et al. (2016), 53 Perrot et al. (2016), 54 Benisty et al. (2016), 55 Monnier et al. (2017), 56 Stolker et al. (2016), 57 Ohta et al. (2016), 58 Willson et al. (2019), 59 Rapson et al. (2015), 60 Wolff et al. (2016), 61 Tanii et al. (2012), 62 van Boekel et al. (2017), 63 Ginski et al. (2018), 64 Oh et al. (2016), 65 Long et al. (2018), 66 Keppler et al. (2018). ...
Accreting protoplanets are windows into planet formation processes, and high-contrast differential imaging is an effective way to identify them. We report results from the Giant Accreting Protoplanet Survey (GAPlanetS), which collected H α differential imagery of 14 transitional disk host stars with the Magellan Adaptive Optics System. To address the twin challenges of morphological complexity and point-spread function instability, GAPlanetS required novel approaches for frame selection and optimization of the Karhounen–Loéve Image Processing algorithm pyKLIP . We detect one new candidate, CS Cha “c,” at a separation of 68 mas and a modest Δmag of 2.3. We recover the HD 142527 B and HD 100453 B accreting stellar companions in several epochs, and the protoplanet PDS 70 c in 2017 imagery, extending its astrometric record by nine months. Though we cannot rule out scattered light structure, we also recover LkCa 15 “b,” at H α ; its presence inside the disk cavity, absence in Continuum imagery, and consistency with a forward-modeled point source suggest that it remains a viable protoplanet candidate. Through targeted optimization, we tentatively recover PDS 70 c at two additional epochs and PDS 70 b in one epoch. Despite numerous previously reported companion candidates around GAplanetS targets, we recover no additional point sources. Our moderate H α contrasts do not preclude most protoplanets, and we report limiting H α contrasts at unrecovered candidate locations. We find an overall detection rate of ∼36 − 22 + 26 % , considerably higher than most direct imaging surveys, speaking to both GAPlanetS’s highly targeted nature and the promise of H α differential imaging for protoplanet identification.
... We do not resolve the inner w ak e, which is likely o v erlapping with the bright inner ring, although the 2011 H -band Subaru/HiCIAO image of the system shows a tentative extended signal in the annular gap at the expected location of the inner spiral w ak e (tow ards north and north-east; Momose et al. 2015 ). We note a reduction in surface brightness of the outer ring towards MNRASL 522, L51-L55 (2023) Wagner et al. ( 2015 ). For PDS 70 b, we considered the best-fitting BT-SETTL model inferred in Wang et al. ( 2021 ). ...
We present the re-detection of a compact source in the face-on protoplanetary disc surrounding HD 169142, using VLT/SPHERE data in YJH bands. The source is found at a separation of 0${_{.}^{\prime\prime}}$319 (∼37 au) from the star. Three lines of evidence argue in favour of the signal tracing a protoplanet: (i) it is found in the annular gap separating the two bright rings of the disc, as predicted by theory; (ii) it is moving at the expected Keplerian velocity for an object at ∼37 au in the 2015, 2017, and 2019 data sets; and (iii) we also detect a spiral-shaped signal whose morphology is consistent with the expected outer spiral wake triggered by a planet in the gap, based on dedicated hydrodynamical simulations of the system. The YJH colours we extracted for the object are consistent with tracing scattered starlight, suggesting that the protoplanet is enshrouded in a significant amount of dust, as expected for a circumplanetary disc or envelope surrounding a gap-clearing Jovian-mass protoplanet.
... We note a reduction in surface brightness of the outer ring towards PA ∼ -15 • -30 • (also seen in R', I', H and J-band irrespective of instrument, Momose et al. 2015;Monnier et al. 2017;Bertrang et al. 2018;Tschudi & Schmid 2021;Rich et al. 2022), which could be caused by shadowing from either the inner ring or the expected inner spiral wake. Fig. 3 compares our contrast spectrum of HD 169142 b with the expected contrast spectrum for PDS 70 b and for circumplanetary disc (CPD) models presented in Szulágyi et al. (2019), obtained considering the SED of the star presented in Wagner et al. (2015). For PDS 70 b, we considered the best-fit BT-SETTL model inferred in Wang et al. (2021). ...
We present the re-detection of a compact source in the face-on protoplanetary disc surrounding HD 169142, using VLT/SPHERE data in YJH bands. The source is found at a separation of 0.''319 ($\sim$37 au) from the star. Three lines of evidence argue in favour of the signal tracing a protoplanet: (i) it is found in the annular gap separating the two bright rings of the disc, as predicted by theory; (ii) it is moving at the expected Keplerian velocity for an object at $\sim$37 au in the 2015, 2017 and 2019 datasets; (iii) we also detect a spiral-shaped signal whose morphology is consistent with the expected outer spiral wake triggered by a planet in the gap, based on dedicated hydrodynamical simulations of the system. The YJH colours we extracted for the object are consistent with tracing scattered starlight, suggesting that the protoplanet is enshrouded in a significant amount of dust, as expected for a circumplanetary disc or envelope surrounding a gap-clearing Jovian-mass protoplanet.
... Despite its evolved state and the significant gas clearing of the inner ∼20 au region, HD169142 still has a near-infrared (NIR) excess, indicating the existence of warm dust (T ∼ 1500 K) in the sub-astronomical-unit inner disk region. Wagner et al. (2015) revealed a fading trend in the NIR, indicating that the inner warm dust has lost half of its fractional luminosity in no more than 10 yr. With NIR interferometry, we constrained the location and grain size distribution of the dust (Chen et al. 2018), finding it most likely to be optically thin dust located at ∼0.08 au from the central star, consisting of mainly large dust grains (>1 μm). ...
... The data set we collected suggests that HD169142 is stable in the optical, but likely has complex variability in the NIR. While Wagner et al. (2015) have already revealed an NIR fading of HD161942 from pre-2000 to post-2000, we found that the object might have exhibited further flux changes in the NIR since 2010. In the WISE light curves (Figure 2), the object seems to be brightening in 2010, and also brightened between 2014 and 2018. ...
The Herbig Ae star HD 169142 is known to have a gaseous disk with a large inner hole, and also a photometrically variable inner dust component in the sub-astronomical-unit region. Following up on our previous analysis, we further studied the temporal evolution of inner dust around HD 169142, which may provide information on the evolution from late-stage protoplanetary disks to debris disks. We used near-infrared interferometric observations obtained with the Very Large Telescope Interferometer/PIONIER to constrain the dust distribution at three epochs spanning six years. We also studied the photometric variability of HD 169142 using our optical–infrared observations and archival data. Our results indicate that a dust ring at ∼0.3 au formed some time between 2013 and 2018, and then faded (but did not completely disappear) by 2019. The short-term variability resembles that observed in extreme debris disks, and is likely related to short-lived dust of secondary origin, though variable shadowing from the inner ring could be an alternative interpretation. If confirmed, this is the first direct detection of secondary dust production inside a protoplanetary disk.
... Despite its evolved state and the significant gas clearing of the inner ∼20 au region, HD 169142 still has a near-infrared (NIR) excess, indicating the existence of warm dust (T ∼1500 K) in the sub-au inner disk region. Wagner et al. (2015) revealed a fading trend in the NIR, indicating that the inner warm dust has lost half of its fractional luminosity in no more than 10 years. With NIR interferometry, we constrained the location and grain size distribution of the dust (Chen et al. 2018), finding it most likely to be optically thin dust located at ∼0.08 au from the central star, consisting of mainly large dust grains (>1 µm). ...
... The data set we collected suggests that HD 169142 is stable in the optical, but likely has complex variability in the NIR. While Wagner et al. (2015) have already revealed a NIR fading of HD 161942 from pre-2000 to post-2000, we found that the object might have exhibited further flux changes in the NIR since 2010. In the WISE light curves (Figure 2), the object seems to be brightening in 2010, and also brightened between 2014 and 2018. ...
The Herbig Ae star HD 169142 is known to have a gaseous disk with a large inner hole, and also a photometrically variable inner dust component in the sub-au region. Following up our previous analysis, we further studied the temporal evolution of inner dust around HD 169142, which may provide information on the evolution from late-stage protoplanetary disks to debris disks. We used near-infrared interferometric observations obtained with VLTI/PIONIER to constrain the dust distribution at three epochs spanning six years. We also studied the photometric variability of HD 169142 using our optical-infrared observations and archival data. Our results indicate that a dust ring at ~0.3 au formed at some time between 2013 and 2018, and then faded (but did not completely disappear) by 2019. The short-term variability resembles that observed in extreme debris disks, and is likely related to short-lived dust of secondary origin, though variable shadowing from the inner ring could be an alternative interpretation. If confirmed, this is the first direct detection of secondary dust production inside a protoplanetary disk.
... HD 163336 was observed with BASS to flux calibrate these data. The instrument and data reduction method are fully described in Wagner et al. (2015). These SpeX, TripleSpec, and BASS spectra are plotted in Figure 2. ...
... The dusty envelope can also include gaps and a bipolar cavity. Following the techniques established by Sitko et al. (2008), Wagner et al. (2015), and Fernandes et al. (2018), we use the dusty envelope as a proxy to model material ejected from the disk, aka a disk wind. We constrained our model-starting parameters by observations when possible, and adopted the parameters from M. Pikhartova et al. (2019, in preparation), who are using HOCHUNK3D to model the variations seen in two epochs of HD163296ʼs SED, as a starting point for our parameter-space exploration. ...
We present H-band polarized scattered light imagery and JHK high-contrast spectroscopy of the protoplanetary disk around HD 163296 observed with the High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO) and Subaru Coronagraphic Extreme Adaptive Optics (SCExAO)/Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) instruments at Subaru Observatory. The polarimetric imagery resolve a broken ring structure surrounding HD 163296 that peaks at a distance along the major axis of 065 (66 au) and extends out to 098 (100 au) along the major axis. Our 2011 H-band data exhibit clear axisymmetry, with the NW and SE side of the disk exhibiting similar intensities. Our data are clearly different from 2016 epoch H-band observations of the Very Large Telescope (VLT)/Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), which found a strong 2.7× asymmetry between the NW and SE side of the disk. Collectively, these results indicate the presence of time-variable, non-azimuthally symmetric illumination of the outer disk. While our SCExAO/CHARIS data are sensitive enough to recover the planet candidate identified from NIRC2 in the thermal infrared (IR), we fail to detect an object with JHK brightness nominally consistent with this object. This suggests that the candidate is either fainter in JHK bands than model predictions, possibly due to extinction from the disk or atmospheric dust/clouds, or that it is an artifact of the data set/data processing, such as a residual speckle or partially subtracted disk feature. Assuming standard hot-start evolutionary models and a system age of 5 Myr, we set new, direct mass limits for the inner (outer) Atacama Large Millimeter/submillimeter Array (ALMA)-predicted protoplanet candidate along the major (minor) disk axis of of 1.5 (2) M J .
... Follette et al. 2017). HD 169142 is a well studied Herbig Ae (Meeus et al. 2010) star at 117 pc (Gaia Collaboration 2016; Michalik et al. 2015, see Tab. 1) hosting a nearly face-on disk often categorized as pre-transitional since it shows dust emissions both at close and large separations from the star separated by several gaps (Wagner et al. 2015;Osorio et al. 2014). The disk has first been spatially resolved by Kuhn et al. (2001, H-band) with polarimetry and studied by Meeus et al. (2001, 2-45 µm) with spectroscopy, and later confirmed by Hales et al. (2006, JHK bands). ...
... Besides, the inner disk at ∼ 0.3 au is known to present a variable Spectral Energy Distribution (SED) in the NIR. Wagner et al. (2015) propose several scenarios to explain the variations of the SED of HD169142, but they invoke stable shadowing effect, otherwise an anti-correlated variability in the emission of the inner and outer disks should be observed in the SED, which is not the case. If additional material exists within our inner working angle, at high altitude, it could shadow the ring at 180 mas, but this remains to be investigated. ...
We present observations of the Herbig Ae star HD169142 with VLT/SPHERE instruments IRDIS (K1K2 and H2H3 bands) and IFS (Y-, J- and H-bands). We detect several bright blobs at ~180 mas separation from the star, and a faint arc-like structure in the IFS data. Our Radial Differential Imaging data analysis also displays a bright ring at the same separation. We show, using a simulation based on polarized light data, that these blobs are actually part of the ring at 180 mas. These results demonstrate that the earlier detections of blobs in H- and K$_s$-bands at these separations in Biller et al. (2014) as potential planet/substellar companions are actually tracing a bright ring with a Keplerian motion. Moreover, we detect in the images an additional bright structure at ~93 mas separation and PA=355{\deg}, at a location very close to previous detections. It appears point-like in the YJ- and K-bands but is more extended in the H-band. We also marginally detect an inner ring in the RDI data at ~100 mas. Follow-up observations are necessary to confirm the detection and the nature of this source and structure.
Context. Most disks observed at high angular resolution show signs of substructures, such as rings, gaps, arcs, and cavities, in both the gas and the dust. To understand the physical mechanisms responsible for these structures, knowledge about the gas surface density is essential. This, in turn, requires information on the gas temperature.
Aims. The aim of this work is to constrain the gas temperature as well as the gas surface densities inside and outside the millimeter-dust cavities of two transition disks: LkCa15 and HD 169142, which have dust cavities of 68 AU and 25 AU, respectively.
Methods. We use some of the few existing ALMA observations of the J = 6-5 transition of ¹³ CO together with archival J = 2−1 data of ¹² CO, ¹³ CO, and C ¹⁸ O. The ratio of the ¹³ CO J = 6−5 to the J = 2−1 transition is used to constrain the temperature and is compared with that found from peak brightness temperatures of optically thick lines. The spectra are used to resolve the innermost disk regions to a spatial resolution better than that of the beam of the observations. Furthermore, we use the thermochemical code DALI to model the temperature and density structure of a typical transition disk as well as the emitting regions of the CO isotopologs.
Results. The ¹³ CO J = 6−5 and J = 2−1 transitions peak inside the dust cavity in both disks, indicating that gas is present in the dust cavities. The kinematically derived radial profiles show that the gas is detected down to 10 and 5-10 AU, much farther in than the dust cavities in the LkCa15 and HD 169142 disks, respectively. For LkCa15, the steep increase toward the star in the ¹³ CO J = 6−5 transition, in contrast to the J = 2−1 line, shows that the gas is too warm to be traced by the J = 2−1 line and that molecular excitation is important for analyzing the line emission. Quantitatively, the 6−5/2−1 line ratio constrains the gas temperature in the emitting layers inside the dust cavity to be up to 65 K, warmer than in the outer disk, which is at 20-30 K. For HD 169142, the lines are optically thick, complicating a line ratio analysis. In this case, the peak brightness temperature constrains the gas in the dust cavity of HD 169142 to be 170 K, whereas that in the outer disk is only 100 K. The data indicate a vertical structure in which the ¹³ CO 6-5 line emits from a higher layer than the 2-1 line in both disks, consistent with exploratory thermochemical DALI models. Such models also show that a more luminous central star, a lower abundance of polycyclic aromatic hydrocarbons, and the absence of a dusty inner disk increase the temperature of the emitting layers and hence the line ratio in the gas cavity. The gas column density in the LkCa15 dust cavity drops by a factor of >2 compared to the outer disk, with an additional drop of an order of magnitude inside the gas cavity at 10 AU. In the case of HD 169142, the gas column density drops by a factor of 200–500 inside the gas cavity.
Conclusions. The gas temperatures inside the dust cavities steeply increase toward the star and reach temperatures of up to 65 K (LkCa15) and 170 K (HD 169142) on scales of ~15–30 AU, whereas the temperature gradients of the emitting layers in the outer disks are shallow, with typical temperatures of 20-30 and 100 K, respectively. The deep drop in gas column density inside the HD 169142 gas cavity at <10 AU could be due to a massive companion of several M J , whereas the broad dust-depleted gas region from 10 to 68 AU for LkCa15 may imply several lower mass planets. This work demonstrates that knowledge of the gas temperature is important for determining the gas surface density and thus whether planets, and if so what kinds of planets, are most likely to be carving the dust cavities.
Context. HD 169142 is part of the class of (pre-)transitional protoplanetary disks showing multiple carbon nanodust spectroscopic signatures (aromatic, aliphatic) dominating the infrared spectrum. Precise constraints on the spatial distribution and properties of carbonaceous dust particles are essential to understanding the physics, radiative transfer processes, and chemistry of the disk. The HD 169142 disk is seen almost face-on and thus it offers a unique opportunity to study the dust radial evolution in disks.
Aims. We investigate the spatial distribution of the carriers of several dust aromatic emission features of the disk across a broad spatial range (10–200 AU) as well as their properties.
Methods. We analysed imaging and spectroscopic observations in the 8–12 µm range from the VLT Imager and Spectrometer for mid-Infrared (VISIR) at the Very Large Telescope (VLT), as well as adaptive optics spectroscopic observations in the 3–4 µm range from the Nasmyth Adaptive Optics System – Near-Infrared Imager and Spectrograph (NACO) at VLT. The data probe the spatial variation of the flux in the 3.3 µm, 8.6 µm, and 11.3 µm aromatic bands. To constrain the radial distribution of carbonaceous nano-grains, the observations were compared to model predictions using The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS), which is integrated into the POLARIS radiative transfer code by calculating the thermal and stochastic heating of micro-and nanometer-sized dust grains for a given disk structure.
Results. Our data show predominant nano-particle emission at all radii (accessible with our resolution of about 0.1″ or ~12 AU at 3 µm and ~0.3″, 35 AU at 10 µm) in the HD 169142 disk. This unambiguously shows that carbonaceous nano-grains dominate radiatively the infrared spectrum in most of the disk, a finding that has been suggested in previous studies. In order to account for both VISIR and NACO emission maps, we show the need for aromatic particles distributed within the disk from the outermost regions to a radius of 20 AU, corresponding to the outer limit of the inner cavity derived from previous observations. In the inner cavity, these aromatic particles might be present but their abundance would then be significantly decreased.
Transition disks with large inner dust cavities are thought to host massive companions. However, the disk structure inside the companion orbit and how material flows toward an actively accreting star remain unclear. We present a high-resolution continuum study of inner disks in the cavities of 38 transition disks. Measurements of the dust mass from archival Atacama Large Millimeter/Submillimeter Array observations are combined with stellar properties and spectral energy distributions to assemble a detailed picture of the inner disk. An inner dust disk is detected in 18 of 38 disks in our sample. Of the 14 resolved disks, 8 are significantly misaligned with the outer disk. The near-infrared excess is uncorrelated with the mm-dust mass of the inner disk. The size–luminosity correlation known for protoplanetary disks is recovered for the inner disks as well, consistent with radial drift. The inner disks are depleted in dust relative to the outer disk, and their dust mass is uncorrelated with the accretion rates. This is interpreted as the result of radial drift and trapping by planets in a low α (∼10 ⁻³ ) disk, or a failure of the α -disk model to describe angular momentum transport and accretion. The only disk in our sample with confirmed planets in the gap, PDS 70, has an inner disk with a significantly larger radius and lower inferred gas-to-dust ratio than other disks in the sample. We hypothesize that these inner disk properties and the detection of planets are due to the gap having only been opened recently by young, actively accreting planets.
