MIRI and NIRCam Coronagraphy of the Beta Pictoris Debris Disk

This example science program presents an application of the high-contrast imaging Roadmap, demonstrating how to create a cross-instrument MIRI/NIRCam program to observe the debris disk around Beta Pictoris.

Example Science Program #35

Main article: HCI Roadmap
See also: Step-by-Step ETC Guide for NIRCam and MIRI Coronagraphy of the Beta Pictoris Debris DiskStep-by-Step APT Guide for NIRCam and MIRI Coronagraphy of the Beta Pictoris Debris Disk

This example science program provides a walk-through of a JWST observing program using the NIRCam and MIRI Coronagraphic imaging, focussing on the overarching goals of the JWST Guaranteed Time Observation (GTO) program "Coronagraphy of the Debris Disk Archetype Beta Pictoris" (PI: Chris Stark). This article discusses how to assess the feasibility and ultimately design a high-contrast imaging (HCI) observing program with JWST, and also links to further articles discussing how to navigate the Exposure Time Calculator (ETC) to determine exposure times required to meet the science goals, and how to set up the observation templates in the Astronomer Proposal Tool (APT). 



Science goals

The debris disk around Beta Pictoris (Beta Pic) is famous for being the first circumstellar disk to be spatially resolved. Since the discovery with IRAS of its thermal excess emission above that expected from the stellar photosphere in 1983, and subsequent ground-based coronagraphic images in 1984, generations of observations have delivered insights into its complex structure, the composition of its constituent particles and the physical processes that shape the disk. As one of the brightest and largest (in angular size) disks on the sky, it remains a compelling target for detailed investigations at unprecedented sensitivities with JWST.  

The science case described here is based on the "Coronagraphy of the Debris Disk Archetype Beta Pictoris" GTO Program. The goal of this program is to characterize the archetypical debris disk around Beta Pic with deep imaging in multiple filters across JWST’s entire wavelength range. Specific objectives include:

  • Measuring the disk structure, composition and interactions with planets.
  • Testing for the presence of water and CO2 ices and organic tholins (such as those on Titan).
  • Measuring color variations and asymmetries across the disk.
  • Probing the thermal emission from both the warm inner belt and outer cooler main disk.
  • Obtaining a comprehensive legacy dataset on this target, for analysis alongside similar data and/or on other debris disks studied using JWST.


Walkthrough of the JWST HCI roadmap

Main article: HCI Roadmap

The HCI roadmap guides readers through the process of designing a high-contrast imaging (HCI) observing program with JWST. Here we demonstrate this process, walking the user through the decisions made at each stage for this example science program.

Stage 1: Become familiar with the HCI capabilities and instrument-specific modes of JWST  

Main article: JWST High-Contrast Imaging
See also: Getting Started Guide

The first stage in the process of planning any HCI program with JWST is to become familiar with the JWST HCI capabilities and terminology. Observers should become acquainted to the various high-contrast imaging articles, in particular the observing modes and optics that enable HCI with JWST; as well as the particular primary performance metricsoperations and recommended strategies for HCI. Observers should also consult the JWST Getting Started Guide, which provides more general instructions for planning JWST observations.

Stage 2: Evaluate the required observations with respect to the performance limits and capabilities of the HCI observing modes

Main article: JWST High-Contrast Imaging
See also: MIRI Coronagraphic ImagingNIRCam Coronagraphic Imaging

For a given JWST HCI investigation, the intended science ultimately determines the choice of high-contrast imaging mode, depending on the wavelength(s) of interest and, to some extent, on contrast and separation of the science target from the central bright object (his star in this case).  Therefore, consider the following:

  1. What is the wavelength range of interest and how does this influence (or limit) the choice of instrument(s), mask(s) and filter(s)?
          Main articles: NIRCam Filters for CoronagraphyMIRI Coronagraphic imaging filters
          See also: NIRCam Coronagraphic Occulting Masks and Lyot StopsMIRI Coronagraph Masks

    In order to achieve the science goals of this program, multi-wavelength, high-spatial resolution imaging of the Beta Pic debris disk from the near- to mid-Infrared are required. Resolved images at multiple wavelengths enable detailed characterization of debris disks: images can provide an independent measurement of the spatial distribution of the dust, while the variation of its brightness with wavelength allows for the size distribution and composition of the dust to be constrained (e.g. Debes et al 2008; Rodigas et al 2015). Therefore, this program employs the NIRCam and MIRI coronagraphs to cover the wavelength range 1.8-23 μm.

    Using the NIRCam Coronagraphs will enable us to obtain images of Beta Pic with HST-like resolution at near-IR wavelengths, with great sensitivity. This program uses NIRCam’s F182M, F210M, F250M, F300M, F335M and F444W medium band filters (sensitive to the presence of water and CO ices, and organic tholins) to characterize the composition and spatial variations of the dust. In addition to revealing the disk in detail, the F444W observations enable the search for unknown, wide-separation (>10AU) planetary companions, reaching well below the mass of Saturn.

    Figure 1: Laboratory reflectance spectra of water ice, CO2 ice and Tholins, and filter throughput curves of NIRCam.

    Figure courtesy of Andras Gaspar et al. (NIRCam GTO).
    For the NIRCam observations, the round coronagraphic masks are used to obtain full azimuthal coverage of the disk, and allow study of its vertical structure.  The MASK210R coronagraphic mask is used for the two filters in the short wavelength (SW) channel (i.e. F182M and F210M) and MASK335R for all four filters in the long wavelength (LW) channel (i.e. F250M, F300M, F335M and F444W). The rational for using only MASK335R (as opposed to both MASK335R and MASK430R) for the LW observations is that it avoids the cost of performing target acquisition (TA) between a change in coronagraphs. 

     Any change of mask requires a new Target Acquisition (TA) with associated overheads (up to 15 minutes depending on the brightness of the star, generally longer for fainter stars).

    The MIRI Coronagraphs will enable imaging of faint disk structures close to the star that have been unresolvable until now. For MIRI, the coronagraphic imaging filters are associated directly with each coronagraph and are not interchangeable—selecting the filter selects the coronagraph. The F1550C coronagraphic filter is used to probe the thermal emission from the warm inner belt, and the broadband F2300C coronagraphic filter to image the thermal emission from the outer cooler main disk.

  2. Can choice of instrument(s) and mask-filter combination(s) achieve the required working angles?
          Main article: HCI Inner Working Angle

    With JWST coronagraphy, the achievable inner working angles (IWAs) vary with wavelength and type of coronagraphic mask. The design specification is IWA = Nλ/D, where the nominal aperture diameter is D = 6.5 m, λ is a fiducial wavelength, and N = 6 for the NIRCam round occulters, N = 3.3 for MIRI Lyot-type Coronagraph and N = 1 for MIRI's 4QPMs

    Specifically, the NIRCam MASK210R and MASK335R round occulters will allow imaging the disk outward of 0.4" and 0.64", respectively; while the MIRI
     4QPM at 15.5 μm and Lyot coronagraph at 23 μm probe the warm inner belt beyond 0.49" and the thermal emission of the cooler main disk beyond 2.16", respectively. 

  3. Are the observations feasible given the contrast limits of the instrument(s)?
          Main article: HCI Contrast Considerations

    The companion-to-host flux ratio expected to achieve for Beta pic is ~2x10−3 (Lagrange et al. 2000), which will be feasible given the achievable contrasts of NIRCam and MIRI.

  4. How important is the azimuthal coverage around the science target?
           Main articles: MIRI Coronagraph MasksNIRCam Coronagraphic Occulting Masks and Lyot Stops

    For NIRCam observations, the uninterrupted 360º fields of view provided by the round occulters make them the best choice for these disk observations and planet search. Because the Beta Pic disk is edge-on, care must be used to orientate the disk away from obscurations in the MIRI coronagraphic fields of view, including the boundaries of the 4QPM and the supporting struts for the Lyot coronagraph.

  5. Is it possible that the scientific goals can be achieved with non-coronagraphic PSF subtraction? 
          Main article: JWST Imaging

    The angular sensitivity and contrast ratios required by this program can not be achieved through regular imaging. Thus, this source requires observations with the coronagraphs for the combination of wavelength coverage and sensitivity.

Stage 3: Select a PSF calibration strategy

Main article: HCI PSF Reference Stars
See also: NIRCam Coronagraphic PSF Estimation

  1. Which observing technique(s) will be included in the PSF subtraction strategy?
        The Referenced Differential Imaging (RDI) technique? — Required          (tick)
        The Angular Differential Imaging (ADI) technique? — Recommended      (tick)    
        The Small Grid Dithering (SGD) technique? — Optional                             (error)

    In order to achieve the best contrast and utilize the smallest inner working angles of each coronagraph, a nearby and color- and flux-matched PSF reference source is observed, using contemporaneous and identically executed observation sequences. The 
    standard coronagraphic sequence for every instrument, mask and filter combination is employed: an initial observation orientated at a desired nominal aperture position angle (i.e. one that maximizes the spatial coverage of the disk); followed by a second observation with an aperture position angle ~10 degrees relative to the first observation; followed by an observation of the PSF reference star. Furthermore, all observations will be linked in a non-interruptible sequence to ensure the PSF calibrator is observed close in time to the science target. Lastly, because of the brightness of Beta Pic, the small grid dithering technique is likely not required

Stage 4: Assess target visibilities and allowed position angles 

Main article: JWST Coronagraphic Visibility Tool Help
See also: JWST Position Angles, Ranges, and OffsetsJWST Target Viewing ConstraintsJWST General Target Visibility Tool Help

  1. Familiarity with JWST position angles, coordinate systems, and pointing constraints.
          Main articles: JWST Position Angles, Ranges, and OffsetsJWST Instrument Ideal Coordinate SystemsJWST Observatory Coordinate System and Field of Regard

  2. Are there any viewing constraints on the target?
          Main article: JWST Target Viewing Constraints

    Coronagraphic observations have additional constraints that go beyond target visibility, such as the placement and orientation of known sources on the coronagraphic masks, or offsets between multi-roll observations. Indeed, some preplanning may save significant time and possibly wasted effort downstream, in the event that certain desired angles or offsets are not available due to observatory level constraints.

  3. What are the target visibilities and allowed position angles versus time?
          Main article: JWST Coronagraphic Visibility Tool Help


    The target visibilities and allowed position angles versus time can be determined using the JWST Coronagraphic Visibility Tool (CVT)—a GUI-based tool developed specifically for pre-planning and strategizing coronagraphic observations with NIRCam and MIRI. In addition to overall target visibility information, the CVT provides information on the location of assumed companions relative to instrumental structures, such as occulting bars in NIRCam or boundaries in the MIRI 4QPM coronagraphs, as a function of time, and shows how the instantaneous roll flexibility changes (from approximately ±3.5° to ±7° from nominal) over the visibility period. 

    After installing and opening the CVT, the CVT is used to determine the observability of Beta Pic. In the control panel, the SIMBAD Target Resolver retrieves Beta Pic's RA, Dec and Ecliptic coordinates, and then the Update Plot button calculates and displays the target’s visibility. The plot generated on the left shows the target's visibility windows, where the red highlights on the solar elongation line indicate the valid target's visibility windows, and the blue tracks show the allowed position angles for the selected instrument and mask over those windows (see Figure 2).

  4. Do the observations require any restrictions on the orientation of the instrument field of view (FOV)/ detector being referenced?
          Main article: CVT Help: Adding companions to the primary target

    In order to determine the ideal placement and orientation of the disk, the CVT is used to judge the extent of the disk in the coronagraphic fields of view. Beta Pic's mid-plane is at a PA of ~30°, with inner and outer radii of ~1.2" and 11", respectively (Apai et al. 2015). The CVT allows the placement of up to 3 companions relative to the primary target, so we define a companion PA of 30° and Sep of 1.2" (to represent the inner radius of the disk); a second companion with a PA of 32° and Sep of 11" (to represent the outer radius of the disk); and a third companion, diametrically opposed to the second, with a PA of 210° and Sep of 11" (representing the other side of the disk). For each planned observation, the corresponding instrument and mask are selected (see Figure 2).

    Because the observations are split into two separate groups/ sequences, slightly different orientations for the MIRI and NIRCam observations can be chosen. The aim is to determine orientations that maximize the spatial coverage of the disk, but that are not coincident with any obscurations in the coronagraphic fields of view.

    For the NIRCam observations, because the disk is edge-on, an orientation is chosen that places the disk mid-plane near the diagonal of the NIRCam coronagraph subarray to maximize spatial coverage, but avoids the ND spots. The ideal orientation would be at an aperture position angle (APA) of ~350°, and other orientations would sacrifice some of the science. Consequently, an APA range of 345°–360° will be suitable for the NIRCam observations.

    For MIRI, the disk is oriented at an angle of ~45° from the 4QPM axes, which corresponds to an APA of ~345°. Note that this orientation also avoids the two supporting struts in the mounting bracket of the Lyot coronagraph, which themselves block light in the FOV. The corresponding APA lies in the range of 340°–355°, placing the disk in quadrants 2 and 4 of the 4QPM (thus we will specify that TA is performed in quadrant 1).

    Figure 2: Coronagraphic Visibility Tool outputs for Beta Pictoris.

    Left: Observability of Beta Pictoris. Center: The field of view of the NIRCam 210R mask (red dashed line), where the red shaded areas represent the various obscurations due to hardware. The added companions' positions as a function of time within the visibility window(s) are marked as tracks with red, blue, and purple (see legend). Right: The field of view of the MIRI Lyot mask (red dashed line), where the blue shaded areas indicate the location of the 4QPM axes. The added companions' positions as a function of time are marked by blue, red and purple tracks. 


    Note that these specific PA range requirements are not completely rigid. In the event of a target acquisition issue or other scheduling problem, one could consider alternative orientations. For the MIRI observations in particular, the only requirement is that the disk mid-plane is oriented near ~45 deg from the 4QPM axes—there are several orientations acceptable, but only one choice is allowed in APT. For NIRCam, the orientation requested is ideal; however, alternative orientations could be considered if absolutely necessary. 

  5. How does the roll flexibility changes over the visibility period?
          Main article: JWST Target Viewing Constraints
          See also: JWST Position Angles, Ranges, and Offsets

    Given the observing restrictions determined above, this program adopts a relative roll angle between observations of 10° to 14°. The CVT is also used to check that the disk does not become incident with any of the instrumental obscurations following a 14° telescope roll from an orientation in the APA ranges defined above.

  6. Do the goals call for a larger roll offset on the science target than can be obtained instantaneously in a single visibility period?
          Main article:  HCI Coronagraphic Sequences: Larger roll offset case

    This program does not require the use of a larger roll offset.

Stage 5: Use the Exposure Time Calculator to determine observing parameters

Main article: JWST Exposure Time Calculator Overview
See also: HCI ETC Instructions

Once target visibility is confirmed and a PSF calibration strategy adopted, the JWST Exposure Time Calculator (ETC) is used to determine the optimal exposure specifications for the program. Step-by-step ETC calculation instructions can be found in the Step-by-Step ETC Guide for NIRCam and MIRI Coronagraphy of the Beta Pictoris Debris Disk article.

Stage 6: Select a Suitable PSF Calibrator

Main articles: HCI PSF Reference Stars

  1. What is the choice of PSF calibrator?
          Main article: Selecting PSF reference stars with Simbad
          See also: Selecting PSF reference stars with SearchCal 

    In the PSF calibration strategy developed above, the need for an appropriate PSF reference star was established. Using Simbad's Query by criteria form, a search for a star in the vicinity of Beta Pic with similar properties is performed using the following search expression:

    rah >= 04 & rah <= 07 & dec > -70 & dec < -40 & Kmag <= 4 & sptypes <= 'A9'

    The returned results are:

    Number of objects : 6
    
    #|       identifier        |typ|  coord1 (ICRS,J2000/2000)   |Mag V |Mag K |  spec. type   |#bib|#not
    -|-------------------------|---|-----------------------------|------|------|---------------|----|----
    1|* bet Pic                |*  |05 47 17.08769 -51 03 59.4412| 3.86 | 3.48 |A6V            |1149|   1
    2|* del Dor                |*  |05 44 46.37811 -65 44 07.9011| 4.36 | 3.71 |A7V            |  50|   0
    3|* alf Dor                |a2*|04 33 59.77719 -55 02 41.9243| 3.28 | 3.52 |B8IIIpSi       |  46|   0
    4|* nu. Pup                |Ce*|06 37 45.67135 -43 11 45.3602| 3.17 | 3.39 |B8III          |  35|   0
    5|* alf Car                |*  |06 23 57.10988 -52 41 44.3810|-0.74 |-1.35 |A9II           | 149|   0
    6|* alf Pic                |PM*|06 48 11.45512 -61 56 29.0008| 3.30 | 2.570|A8VnkA6        |  67|   0
    ================================================================================


    To identify Alpha Pictoris ("* alf Pic") as a potential PSF reference target, the following criteria is considered:

    • Well-known: Is the target a known good PSF reference star?
      Selecting a reference PSF source that has been perviously observed coronagraphically and found to be single, is recommended. "Good references" are usually stars that are not astrophysically contaminated (i.e., without additional astrophysical signal from a debris disk or companion). Alpha Pic is a known single star and has been successfully used as a PSF calibrator for Beta Pic in many HST observations.


    • Schedulability: Do the visibility windows of the science target and PSF calibrator overlap at the time of the desired observation?
      In order to observe the science target and PSF reference star in a contiguous, non-interruptible sequence, both objects should be observable at contemporaneously. With the restrictions on the observability Beta Pic known (from previous work in the CVT), the CVT is used to verify that Alpha Pic is indeed visible at the same time as Beta Pic, finding that there are two periods over which the targets' visibility windows overlap: Jan 1st–Apr 4th and Sept 27th–Dec 31st (see Figure 3).

    • Proximity: Is the PSF calibrator in relatively close proximity to the science target?
      The JWST PSF is expected to be time variable, which has important consequences on the choice of PSF reference targets. In order to minimize changes in the JWST wavefront between science and PSF reference star observations, a reference star that is in close temporal and physical proximity to the science target should be chosen. Choosing a nearby reference star also minimizes the telescope overheads (by reducing slew time). Alpha Pic has J2000 co-ordinates (ICRS) of 06 48 11.4551 (RA), -61 56 29.00 (Dec) and is located ~19° from Beta Pic (which has J2000 co-ordinates of 05 47 17.0877, -51 03 59.44).

    • Avoidance of Binary: Is the PSF calibrator a single and unresolved source?
      In order to ensure effective PSF subtraction, it is important to chose a star that is single and not astrophysically contaminated (i.e., without additional astrophysical signal from a debris disk or companion). Alpha Pic is a known non-binary star and so will appear optically single at JWST resolution. Using the Vizier Photometry viewer, it is verified that there is no obvious IR excess around Alpha Pic.

    • Spectral Type: Does the PSF calibrator share the same spectral properties as the science target?
      Spectral mismatch between a science target and its corresponding PSF reference star may degrade the fidelity of the PSF subtraction process. 
      Alpha Pic (A8V) is fairly close in spectral type to Beta Pic (A6V), which provides a more than adequate color match (given previous estimates of the impact of color mismatch on NIRCam coronagraphy contrast) to minimize chromatic differences between the reference PSF and target PSF. For the MIRI observations, color match is less important for stellar point-sources, since their photospheric spectral energy distributions follow a Rayleigh distribution at these wavelengths..

    • Brightness: Is the PSF calibrator similar in magnitude to the science target?
      Whenever possible, it is recommended to use a reference PSF that is at least as bright as the primary target. Strong preference for reference PSF sources brighter than the science target should be considered, so that the noise (and any background) is not scaled during the flux rescaling process. The difference in K mag between Alpha Pic (K=2.57) and Beta pic (K=3.48) is ~0.9. This will enable for a shorter exposure time on PSF star, and therefore provide savings in the total time of the program.

  2. Returning to the previous ETC workbook, what are the final exposure parameters for the PSF reference star observations?

    Because Alpha Pic is 0.9 mag brighter than the science target, in order to achieve similar photon noise level on the speckles we reduce the exposure times to be roughly half as long in each filter. For the MIRI coronagraphic observations in both F1550C and F2300C filters we reduce the number of Integrations per exposure to "30". For the NIRCam observations we reduce the number of integrations per exposure to "50" for the F182M and F210M observations; "40" for the F250M and F300M observations; and "20" for the F335M and F444W observations.

Stage 7: Finalize the observing strategy

Main article: HCI Roadmap
See also: HCI Coronagraphic SequencesMIRI Observing StrategiesNIRCam Observing Strategies

A series of technical decisions for the program (such as our PSF calibration strategy, exposure specifications, etc.) have been made, and now an observing strategy needs to be identified that incorporates each of these components, whilst also minimizing observing overheads and performance degradation. 

  1. What is the total number of observations require for the observing program?

    This program requires a set of 6 NIRCam coronagraphic observations: 

    • Beta Pic in the LW filters at one spacecraft orientation  LW Roll 1
    • Beta Pic in the LW filters at a different spacecraft orientation  LW Roll 2
    • Alpha Pic in the LW filters  LW Reference PSF
    • Beta Pic in the SW filters at one spacecraft orientation  SW Roll 1
    • Beta Pic in the SW filters at a different spacecraft orientation  SW Roll 2
    • Alpha Pic in the SW filters  SW Reference PSF

    and a set of 6 MIRI coronagraphic observations :

    • Beta Pic with F1550C at one spacecraft orientation  4QPM Roll 1
    • Beta Pic with F1550C at a different spacecraft orientation  4QPM Roll 2
    • Alpha Pic with F1550C  4QPM Reference PSF
    • Beta Pic with F2300C at one spacecraft orientation  Lyot Roll 1
    • Beta Pic with F2300C at a different spacecraft orientation  Lyot Roll 2
    • Alpha Pic with F2300C  Lyot Reference PSF


  2. How will the observations be organized?
          Main article: HCI Coronagraphic Sequences

    There are two strategies in which to schedule the set of observations. In the first approach, the observations made in each instrument are scheduled together in a non-interruptible sequence, at the orient in which the spatial coverage of the disk is maximized. Alternatively, by making a slight sacrifice in orientation and requiring that the NIRCam and MIRI observations be scheduled together in one long non-interruptible sequence (with the PSF reference observations placed between them) it is possible to save on overheads. However, this second approach puts very tight restrictions on the schedulability of the observations, resulting in a single two-day scheduling window. This is potentially problematic: if any observation failures were to occur that were not caused by the program itself (e.g., caused by an instrument or telescope operational problem, malfunction or safing event), there would not be another opportunity in which to repeat this sequence of observations within that observing cycle—the program would need to be deferred for at least another year. Thus, the first scheduling approach is adopted. This increases the schedulability of the observations from ~2 days per year to ~2 weeks and allows slightly more ideal instrument orientations, at the expense of slightly longer overheads. Note that if there is a target acquisition issue or something that prevents scheduling of the observations, there are other possible orientations that are available other than those provided. 

    The order in which the two sets of observations will be scheduled is as follows:

    Table 1. Beta Pictoris observation techniques with NIRCam and MIRI coronagraphs

    Observing Beta Pictoris with the NIRCam coronagraphs

    Observing Beta Pictoris with the MIRI Coronagraphs:

    Slew to PSF reference star

    • Observe PSF reference star with NIRCAM LW filters
    • Observe PSF reference star with NIRCAM SW filters

    Slew to science target 

    • Observe science target with NIRCAM SW filters

    Roll Observatory ~12° 

    • Observe science target with NIRCAM SW filters
    • Observe science target with NIRCAM LW filters

    Roll Observatory ~12° 

    • Observe science target with NIRCAM LW filters

    Slew to science target 

    • Observe science target with MIRI F2300C
    • Observe science target with MIRI F1550C 

    Roll observatory ~12° 

    • Observe science target with MIRI F1550C
    • Observe science target with MIRI F2300C

    Slew to PSF reference star 

    • Observe PSF reference star with MIRI F2300C
    • Observe PSF reference star with MIRI F1550C


    This order is chosen to minimize overheads while also minimizing time between reference PSF observations and science target observations.

Stage 8: Prepare our proposal in the Astronomers' Proposal Tool

Main article: Step-by-Step APT Guide for NIRCam and MIRI Coronagraphy of the Beta Pictoris Debris Disk
See also: JWST Astronomers Proposal Tool Overview

Once all other steps in the proposal planning process are completed, the program can be written, validated and submitted using in the JWST Astronomers Proposal Tool Overview (APT). A step-by-step guide for entering this example science program into the APT is provided in the Step-by-Step APT Guide for NIRCam and MIRI Coronagraphy of the Beta Pictoris Debris Disk article.



References

Apai D., Schneider G., Grady C. A., et al. 2015 ApJ 800 2
The inner disk structure, disk-planet interactions, and temporal evolution in the β Pictoris System: A two-epoch HST/STIS Coronagraphic Study

Augereau J. C., Nelson R. P., Lagrange A. M., et al. 2001 A&A 370 447
Dynamical modeling of large scale asymmetries in the β Pictoris dust disk

Debes, J. H., Weinberger, A. J., & Schneider, G. 2008 ApJL 673 L191 (ADS)
Complex organic materials in the circumstellar disk of HR 4796A

Lagrange, A.-M., Boccaletti, A., Milli, J., et al. 2012 A&A 542 A40 (ADS)
The position of β Pictoris b position relative to the debris disk

Larwood, J. D., & Kalas, P. G. 2001 MNRAS 323 402
Close stellar encounters with planetesimal discs: the dynamics of asymmetry in the βPictoris system

Milli, J., Lagrange, A.-M., Mawet, D., et al. 2014, A&A, 566, A91 (ADS)
Very deep images of the innermost regions of the β Pictoris debris disc at L

Mouillet, D., Larwood, J.D., Papaloizou, J. C. B., et al. 1997, MNRAS, 292, 896
A planet on an inclined orbit as an explanation of the warp in the β Pictoris disc

Rodigas, T. J., Stark, C. C., Weinberger, A., et al. 2015, ApJ 798 2
On the morphology and chemical composition of the HR 4796A debris disk

"Coronagraphy of the Debris Disk Archetype Beta Pictoris" GTO Program

Simbad entry for Beta Pic




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