Young Planets Embedded in Circumstellar Disks

Young planets embedded in circumstellar disks

Sascha P. Quanz (ETH Zurich)

Image credit: ESO/L. Calçada

The National Centres of Competence in Research (NCCR) are a research instrument of the Swiss National Science Foundation Where, when and how do (gas giant) planets form? Gas giant planets are found over a broad range of separations

From radial velocity surveys From direct imaging

HR8799

HD95086 GJ 504

Marois et al 2010; Rameau et al. 2013a,b; Kuzuhara et al. 2013 The physical processes involved in planet formation are largely unconstrained

Spiegel & Burrows 2012 (see also, e.g., Marley et al. 2007) Indirect signatures of planets thanks to high-spatial resolution imaging of disks

Gaps in the HD169142 protoplanetary disks revealed by polarimetric imaging 7

(Sub-mm) interferometry NIR scattered light imaging Distance (AU) Distance (arcsec) −150 −100 −50 0 50 100 150 −1" −0.5" 0" 0.5" 1" N N a) b) 1" 150 150 1" E E 100 100 0.5" 0.5" 50 50

0" Dip 0 0 0"

−50 Distance (AU) −50 Distance (arcsec) −0.5" −0.5" Distance (arcsec) −100 −100 AO feature −1" −150 −150 −1"

−1" −0.5" 0" 0.5" 1" −150 −100 −50 0 50 100 150 Distance (arcsec) Distance (AU)

−1" −0.5" 0" 0.5" 1" 1" The Astrophysical Journal LettersN,729:L17(6pp),2011March10 140 Hashimoto et al. c) d) 150 1" 120 E AU 0.8" 100

AO feature 150 100 50 0 -50 -100 100 50 0 -50 -100 -1500.5" 100 50 0 -50 -100 -150 100 50 -0.5 0 0.5 1 0.6"Ring gap A Outer ring 80 0 0"

0.4" 60 Distance (AU) −50 D Distance (AU) −0.5" Distance (arcsec) E 40 −100 0.2" B

AO feature P1 AU −150 −1" 20 P3 Dip F 0" P2 0 −150 −100 −50 0 50 100 150 0 90 180 270 360 Distance (AU) Degrees eastG of north Dec. offset (arcsecond) Dec. offset N -0.5 0 0.5 1 2 Fig. 1.— NACO/PDI observations of HD169142 in the H band. a) Final Qr image scaled with r to compensate for the decrease in stellar ﬂux (image shown in a linear stretch). The positionE of the centralInner star ring is indicated by the redC cross. Saturated pixels in the central regions have been masked out. Our data reveal a bright inner ring, a large gap and a smooth outer disk in polarized light. A brightness dip in the ring and a residual 0.5 AO feature 0 are indicated -0.5 by arrows. -1 b) Ur with 0.5 the same 0 scaling and-0.5 stretch as -1 for the Qr image. c) Intensity image also scaled with r2.FeaturesfromtheAOsystemandthetelescopespidersareclearlyseen.d)PolarcoordinatemappingofQ . R.A. offset (arcsecond) r Andrews et al. 2011; Hashimoto et al. 2011; 2012; The innermost, masked out region is less than 0.1′′ in diameter. The red line traces the peak brightness of the inner ring.

Quanz et al. 2013b; Havenhaus et al. 2014; Garuﬁ et al. 2013 10 (mJy/arcsec 2 ) 100 100 50 10

Total

G F Surface brightness (mJy/arcsec ) D intensity 2 Polarized E intensity A

P3 P2 P1 2 Surface brightness (mJy/arcsec ) C B 10 50 100 110 120 10 50 100 110 0 100 200 300 0 100 200 300 θ (degree) Figure 2. Magnified view of the inner PI images of AB Aur and their averaged azimuthal profiles. Top: magnified PI image with a coronagraphic occulting mask of 0′′. 3 diameter (left) and the features of the PI image (right). Central position (0, 0) is the stellar position. The outer and inner rings are denoted by the dashed ellipsoids. The solid ellipsoid indicates the wide ring gap. The dashed circles (A to G) represent small dips in the two rings. The filled diamond, circle, and square represent the geometric center of the inner ring, ring gap, and outer ring, respectively. The field of view in both images is 2. 0 2. 0. The solid circle in the left bottom inset ′′ × ′′ represents the spatial resolution of 0′′. 06. Bottom left: averaged azimuthal profiles of the outer ring for the PI (black) and reference PSF-subtracted I (red) images. The profile is averaged every 5◦ in position angle (corresponding to resolution) in the outer ring. Bottom right: same with the bottom left image, but for the inner ring with every 15◦ in position angle (corresponding to resolution) in the inner ring. (A color version of this figure is available in the online journal.)

Our observations are consistent with Perrin et al. (2009). early phase of global evolution, and possibly one or more unseen When we assume that a companion is 100% polarized in planets are being formed in the disk. the PI image, which is the faintest case as Oppenheimer One possible explanation for the non-axisymmetric structures et al. (2008), the upper limits of its mass at 5σ (the absolute is GI of the disk (e.g., Durisen et al. 2007). If Toomre’s magnitude of 11.7 at the H band) of the photon noise in Dip Q-parameter (deﬁned as Q csκ/πG!,wherecs, κ,and! = Aare5and6MJ for an age of 3 and 5 Myr, respectively are the sound speed, epicycle frequency, and surface density, (Baraffe et al. 2003). These derived upper limits of the respectively) is of the order of unity, GI occurs and a mode masses are consistent with that of 1 MJ inferred by the with a small number of arms is excited, that is, a pattern of the numerical simulations (Jang-Condell & Kuchner 2010). On surface density arises that may resemble what we have observed. the other hand, our upper limits for point sources in the dips However, this GI possibility may be rejected for AB Aur seen in the inner ring are 7 and 9 MJ for these ages due to (at present) because optically thin submillimeter observations higher photon noise. indicate that Toomre’s Q-parameter is of the order of 10 (Pietu´ et al. 2005). It may be noted that the disk mass estimate from The structures of AB Aur’s inner (22–120 AU) disk surface submillimeter emission has large uncertainties arising from the described above indicate that the disk is in an active and probably uncertainties in the optical properties of the dust particles.

4 3 systems with promising candidate planets in disks (at the moment) The planet candidate in the LkCa 15 disk

SMA 850 micron + Keck aperture masking (2.3 and 3.8 micron)

•Dust cavity R~40-50 AU (also in scattered light) •Companion candidate in the cavity at ~11 AU

Kraus & Ireland 2012; Andrews et al. 2011; see also Thalmann et al. 2011, 2014, 2015 First attempts to detect the circumplanetary disk around LkCa 15 b

VLA 7mm data

Isella et al. 2014 –11–

0.8 VLA CnB VLA B 7 mm 7 mm 0.4 + + HD169142 - sequential0 planet formation? + + −0.4 1.6 micron scattered light image 7 mm(a) VLA data (b) −0.8

0.8 VLA CnB+B+A VLA 7 mm 7 mm VLT H−Band

DEC offset (arcsec) 0.4 innerinner gapgap (cavity)(cavity) 0 + + ring ring 29 AU outer gap −0.4 outer gap

•Inner cavity <25 AU Fig. 1.— VLA images of the• 7 ~5 mm dustsigma thermal ‘overdensity’ emission in several array configurations. •Annular gap ~40-70 AU Panels (a) and (b) show, respectively, inside the the CnB cavity and B configuration~50 AU images. Panel (c) shows the image obtained by combining the CnB, B, and A configuration visibilities with a uvrange 1 <1500 k (rms=18 µJy beam ; beam=0.23⇤⇤ 0.16⇤⇤, PA=5⇥). Panel (d) shows an overlay ⇥ of the image shown in panel (c) (contours) and the VLT/NACO H-band (1.6 µm) polarized light image from Quanz et al. (2013) (color-scale). Saturated pixels in the central region of the H-band image have been masked out. In all panels, contour levels are 3, 3, 5, 7, 9, and 11 times the rms. Synthesized beams are plotted in the lower-right corners. The apparent Quanz et al. 2013b; Osorio et al. 2014 decrease of the 7 mm emission in the north and south edges of the source is most probably aconsequenceoftheelongatedbeam.ThelargercrossmarksthepositionoftheHD169142 star and the smaller one that of the protoplanet candidate. HD169142 - sequential planet formation?

1.6 micron scattered light image 3.8 micron high contrast image

•Inner cavity <25 AU •3.8 micron point source •Annular gap ~40-70 AU at ~20-23 AU •Not (yet) detected at shorter wavelengths •7mm source not detected

Quanz et al. 2013b; Reggiani, Quanz et al. 2014 (see also, Biller et al. 2014) 4 Avenhaus et al. P P P 5 P ⇥ ⇥ · 2006 Hband

0.5"

The Astrophysical Journal,791:136(7pp),2014August20 Brittain et al.

Table 3 Properties of Excess CO v 1–0 Emission = Date Scaled Equivalent Excess Equivalent Doppler Shift FWHM Position Angle Orbital Phase Red Blue band Widtha Width ofExcess ofExcess ofExcess ofExcessb Offset Offset s

2006 2 1 2 1 1 1 (10− cm− ) (10− cm− )(kms− )(kms− )(mas)(mas)

K 2003 Jan 7 4.50 0.14 40 0 12.7 3.3 14.0 3.3 ± ··· ··· ··· − ◦ ◦ ± ± 2006 Jan 14 5.69 0.59 1.19 0.61 +6 16 5 47 10 1.6 4.3 17.8 4.3 ± ± ± − ◦ ◦ ± ◦ ± ± 2010 Dec 23 6.39 0.57 1.89 0.58 1 1 12 60 97 7 5.7 4.8 25.9 4.8 ± ± − ± ◦ ◦ ± ◦ ± ± 2013 Mar 18 5.89 0.20 1.12 0.15 6 16 105133 10 10.9 0.9 35.8 0.9 ± ± − ± ◦ ◦ ± ◦ ± ± 0.5" Notes. a The spectra were scaled such that the average hot band line proﬁles observed in 2006 and 2010 had the same equivalent widths as the average line proﬁle observed in 2003. b The phase is measured counter clockwise from the northwest end of the semimajor axis of the disk.

vary relative to previous epochs (Figures 3(B) and 4(A)–(D)). (A) We analyze the CO v 1–0 emission using the procedure and 10 rationale outlined in Paper= II.Weﬁrstnormalizethespectrum so that the CO hotband lines have the same equivalent width as A. in the 20032003 spectrum. TableB. 3 shows the2006 scaled EW of the CO v 1–0 emission in the resulting spectrum. We then subtract the= 2003 spectrum to obtain the spectrum of the CO v 1–0 = 2013 HD100546 - sequential planet formationexcess emission again? component (Figure 4). The EW of the excess

Hband CO emission component and its velocity centroid and FWHM are shown in Table 3 where they are compared with the values from all earlier epochs. C. 2010 D. 2013 OH Emission As described in Paper II and summarized in Table 3, between 1.6 micron 2010: Black 2003 and 2006, the red side of the P26 line brightened, the spatial 0.5" 2013: Red offset of the red side of the line decreased, and the CO excess scattered light image High dispersed 4.6 micron spectroscopy 1 emission component had a velocity centroid of +6 1kms− (compare Figures 4(A) and (B)). Similarly, in 2010 the± P26 line brightened further, and the excess emission was centered near 1 zero velocity ( 1 1kms− ). In this part of the line proﬁle, (B) the spatial centroid− ± of the line became offset further to the east CO Emission E. 2006 (Figure 4(C)). Inv the=+6±1 2013 km s-1 epoch reportedE here, the blue side of 2003: Black p the P26 line is againφ=47±10 brightero than in 2003 and the excess is now o 2006: Red blueshifted ( 6 PA=1kms−5o E of N1). The spatial centroidPA=140 of the red side 2010: Blue − ± − 2003 2010of the line is comparable toφ that=0o in 2003 (Table 3), but the blue 2013: Green v =−1±1 km s-1 o pside of the line is now extendedPA=−40 further E of N to the east (Figure 4(D)). φ=97±7o PA=60o E of N band 4. DISCUSSION s 2013 2013 v =−6±1 km s-1 p 4.1. Orbital Analysis o

K φ=133±10 PA=105o EIn of NPaper II,wesuggestedthatthevariationsinthev 1–0 line emission could be explained by the presence of= a 50 au spatially concentrated source of CO emission that orbits the star within the disk wall. A schematic of this scenario is shown 0.5" in Figure 4(E). We can obtain a rough constraint on the orbit of the CO excess component given the velocity centroids observed Fig. 4.— Spectroastrometric signal of the P26 line and schematic of the geometry of the system. In Panels A–D the spectro-astrometric Figure 3. Multi-epoch observations of the of the OH (panelsignal(A)) of the P26 and line CO is plotted. Thein excess 2006, flux of the 2010, P26 line and is plotted 2013. below the Assuming spectro-astrometric a signal system in Panels inclination B–D. For each of (panel (B)) lines. In panel (A), the average of the OH emissionepoch lines the observed spectro-astrometric in signal is calculated from our excitation model with the excess emission added for the data acquired in 2006, 2010, and 2013 (red dot-dashed line).42 In◦ Panel(Ardila E, a schematic et al. of the2007 disk and;Pinedaetal. extra emission source is2014 presented.)andastellarmass The orbit is represented •Inner cavity <14 AU 2010• (black)Fundamental and 2013 (red) are plotted CO over onero-vibrational another. Bothby the lines black have dashed been line. The• innerSpectro-astrometric wall of the disk orange. The location of the source of thesignal emission excess is labeled with a black dot, scaled to a constant equivalent width. The difference betweenand these the uncertainty spectra in isthe phase of theof orbit 2.4 is representedM ,wefitacircularorbittothemeasuredvelocities by the red triangle. In 2003 we assume the emission is hidden by the near side of the circumstellar disk. The phase of the orbit is calculated⊙ from the Doppler shift of the excess emission assuming the disk is inclined Fig. 1.— NACO PDI results in H and Ks filter from epochs 2006 and 2013. From left to right: P ,capturingthestructureofthedisk,plotted above. While the equivalent width of the lines varied,42 theand shape the orbital of radius the is 12.5 AUwith (just inside the the orbital inner rim ofradius the disk).R Inand 2006, the the excess orbital emission pulled phase the center of the of light excess of the in •Brightness asymmetry lines red side of the line closer to theconsistent the center of the PSF. In 2010, with the excess emissionorbiting pulled both sides body of the line eastward along the slit ⇥ lines has not varied to within the signal to noise of our measurement.axis. In 2013, In the panel excess emission on2003 the blue as side freeof the line parameters. pulled the spectro-astrometric The result signal eastward.of a χ 2 fit (Figure 5)gives P ,whichisexpectedtobezeroanddominatedbynoise,P scaled by a factor of five to better show the noise signature, and P ,which(B) we plot the overlapping region of the CO spectra observed over four epochs. Hot-band lines static at ~10-12+1.5 AU +15◦ ⇤ ⇤ • R 12.9 AU and an orbital phase of φ 6◦ ,where The spectra have been scaled so that the equivalent width of the average of the 1.3 20◦ is identical to P in the absence of any noise and when there is no rotation of the polarization due to multiple-scattering eects (see also = − = − hotbandv=1-0 lines is constant. P26 While line the shape varies of the hotband lines has not changed φ 0◦ corresponds to the NW end of the semimajor axis. If ⇥ over• the four epochs spanning 2003–2013, the v 1–0 P26 line has varied. In = text). Positive values are in orange, negative values in blue. The grey area in the center represents positions where no data is available we adopt a higher inclination (e.g., 50◦;compareforexample 2006, the P26 line shows a red excess relative to= the 2003 spectrum. In 2010, 1 Quanz et al. 2011 and Panicetal.´ 2014), our best fit shifts to due to saturation eects. The red cross marks the position of the star. North is up and east is to the left in all images. The imagesthe are excess shows a minimal Doppler shift ( 1 1kms− ) relative to 2003. In − ± +1.6 +13◦ 2013, the P26 line shows a blueshifted excess. R 14.0 1.3 AU and an orbital phase of φ 15◦ . 1.62 ( 160 AU) on each side, they all show the same section of the disk. For reference, there is a scale in each of the P images. All = − = 15◦ (A color version of this figure is available in the online journal.) Hence, the velocity centroids at the three measured− epochs images scaled with r2. are consistent with circular motion and locate the excess source

3.1. Global Scattering Signature of 0.6⇥⇥. Avenhaus, Quanz et al. 2014; Quanz et al. 2011; Brittain et al. 2013,2014 4 With our new data, we confirm the basic disk structure The grains in the disk are preferentially backscattering already described in (Quanz et al. 2011): The major axis in polarization (scattering albedo multiplied with polar- of the disk runs in southeast-northwest direction, and ization fraction, which is what our data measure), which the brightest parts of the disk are along this axis. The makes the far (northeastern) side of the disk appear sig- northeastern part of the disk appears brighter compared nificantly brighter. Furthermore, the polarization e⇥- to the southwestern part. For the first time, we identify ciency in scattering usually peaks around 90 (e.g., Per- a dark lane on this forward-scattering side in all H and rin et al. 2009), which explains the two bright lobes in K filter observations including the cube mode observa- the southeast and northwest: The semi-major axis of the s disk runs along this direction, and the scattering angle tions between 0.2⇥⇥ and 0.6⇥⇥, while the scattered light picks up (in this representation scaled with r2) outside at these positions is close to 90 depending on the exact 4 Avenhaus et al. P P P 5 P ⇥ ⇥ · 2006 Hband

0.5" band s 2006 K

0.5"

2013 HD100546 - sequential planet formation again? Hband

1.6 micron scattered0.5" light image High contrast imaging band s 2013 K

50 au 0.5"

•Inner cavity <14 AU •Point source + plus extended emission at ~52 AU Fig. 1.— NACO PDI results in H and Ks ﬁlter from epochs 2006 and 2013. From left to right: P ,capturingthestructureofthedisk,•Brightness asymmetry •Very red; not detected shortward of 3.8 micron (yet) P ,whichisexpectedtobezeroanddominatedbynoise,P scaled by a factor of ﬁve to better show⇥ the noise signature, and P ,which •Teff ~ 930 K is⇤ identical to P in the absence of any noise and when there⇤ is no rotation of the polarization due to multiple-scattering eects (see also •R = 7 RJupiter text). Positive values⇥ are in orange, negative values in blue. The grey area in the center represents positions where no data is available due to saturation eects. The red cross marks the position of the star. North is up and east is to the left in all images. The images are 1.62 ( 160 AU) on each side, they all show the same section of the disk. For reference, there is a scale in each of the P images. All images scaled with r2.

3.1. Global Scattering Signature of 0.6⇥⇥. Avenhaus, Quanz et al. 2014; Quanz et al. 2011, 2013a, 2015; Currie et al. 2014 With our new data, we confirm the basic disk structure The grains in the disk are preferentially backscattering already described in (Quanz et al. 2011): The major axis in polarization (scattering albedo multiplied with polar- of the disk runs in southeast-northwest direction, and ization fraction, which is what our data measure), which the brightest parts of the disk are along this axis. The makes the far (northeastern) side of the disk appear sig- northeastern part of the disk appears brighter compared nificantly brighter. Furthermore, the polarization e⇥- to the southwestern part. For the first time, we identify ciency in scattering usually peaks around 90 (e.g., Per- a dark lane on this forward-scattering side in all H and rin et al. 2009), which explains the two bright lobes in K filter observations including the cube mode observa- the southeast and northwest: The semi-major axis of the s disk runs along this direction, and the scattering angle tions between 0.2⇥⇥ and 0.6⇥⇥, while the scattered light picks up (in this representation scaled with r2) outside at these positions is close to 90 depending on the exact What’s next? - Get more data…

ALMA cycle 3 simulations (345 GHz)

HD100546 HD169142 Take home messages

For 3 young stars we have observational evidence that young planets might orbit in their disks

If these are indeed forming planets then they are located between ~10-50 AU, i.e., at rather larger separations

The directly imaged planets have very red IR colors indicating the possible existence of warm circumplanetary material

More objects are expected to be found thanks to ongoing ALMA and high-contrast imaging campaigns

These objects allow us to constrain planet formation models with empirical data