Dissertation

bRing (Beta Pic b RING experiment)

University of Rochester

Siding Springs, Australia bRing team: Samuel Mellon (Ph.D. student, U. Rochester), Mike Culver (U. Rochester), Eric Mamajek (PI; U. Rochester, JPL/Caltech), Michael Ireland (Australia National U.)

Sutherland, South Africa bRing teamMatt Kenworthy (Leiden), Remko Stuik (Leiden), Jeb Bailey (Leiden), Patrick Dorval (Master's student, Leiden), Iva Laginja (STSI, previously Leiden), Steve Crawford (SAAO), Blaine Lomberg (SAAO, University of Cape Town)



Summary: The bRing experiment ("Beta Pic b Ring") consists of twin two-camera instruments which will monitor the bright star Beta Pictoris throughout 2017 and 2018 for signs of obscuration from circumplanetary dust associated with the young gas giant exoplanet Beta Pic b. The bRing instruments will be part of an international campaign to monitor the Beta Pic system in 2017-2018. The 2017-2018 Beta Pic transit season represents the first time that an imaged extrasolar planet will be monitored coming close to passing in front of its star. It will be the best opportunity yet for observational constraints on the late stages of gas giant planet formation and the nature of circumplanetary disks, which may spawn exomoons. The bRing experiment will comprise part of my Ph.D. dissertation.

The Instrument: bRing is a 2-camera robotic observatory designed by Remko Stuik (Leiden) based on a scaled-down version of the successful 5-camera MASCARA system (sited at La Palma and La Silla). The bRing box will contain computers which will process the data from the cameras and transmit processed photometric data back to Rochester and Leiden (approximate photometric accuracy <0.5%, cadence 5 minutes). The UR bRing instrument will be sited on a concrete platform adjacent to the ANU 16-inch telescope at Siding Springs Observatory.

Illustration of exterior of the 2-camera bRing instrument.
bRing occupies approximately a cubic meter of volume.
(R. Stuik, Leiden)

The Exoplanet: The young (23±3 million years; Mamajek & Bell 2014gas giant planet (mass ~12.7 times the mass of Jupiter; Wang et al. 2016) was discovered by Lagrange et al. (2016) via direct imaging in the infrared using the NaCo instrument on the Very Large Telescope (VLT). Beta Pic b is the closest, young imaged exoplanet at 19 parsecs; Beta Pic b orbits its star every ~22 years.

Composite image of star Beta Pictoris (light obscured), the exoplanet Beta Pic b, and the reflected light from the star's dusty debris disk. Beta Pic b will come within 10 milliarcseconds of passing in front of the star Beta Pic in mid-2017.
Image credit: ESO/A.-M. Lagrange et al.

The Transit: A direct transit of the exoplanet beta Pic b has been statistically ruled out, and is predicted to miss the star beta Pic by a scant 10 milliarcseconds (Wang et al. 2016). The region where the planet's gravitational influence dominates (its "Hill sphere") will transit the bright star Beta Pic betwen April 2017 and January 2018. Any circumplanetary material (disk, rings, exomoons, etc.) orbiting the exoplanet Beta Pic b would most likely orbit within about half of the Hill radius, which will transit the star between around 20 June 2017 and 12 November 2017.

Why Search? Theorists have long predicted that the gas giant planets in our own solar system must have circumplanetary disks of dust (and gas) early in their history in order to explain the existence and properties of the large, regular satellites (e.g. Galilean satellites around Jupiter). It is reasonable to suspect that beta Pic b may host circumplanetary material within its Hill sphere (<1.2 AU). First, the system is very young (~23 million years), and the star Beta Pic famously has a very dense circumstellar dusty debris disk. It is possible that rapid photometric variations of Beta Pic observed in 1981(!) - long before the discovery of either the exoplanet or the debris disk - may have been due to material associated with the exoplanet (Lecavelier des Etangs & Vidal-Madjar 2009). Evidence for circumplanetary disks have been seen around slightly younger systems (the transiting ring system associated with J1407b, the imaged accreting protoplanet LkCa 15b).  

Given that giant planets appear to be very common around stars in our Galaxy, exomoons are likely to be very common too. Observations with bRing and other instruments monitoring Beta Pic may provide strong constraints on the existence, size, and mass of circumplanetary material (moon-forming disk?) around a young gas giant planet. This would represent the first time that circumplanetary matter associated with an imaged exoplanet will have been seen passing in front of a star (and with plenty of time to prepare to observe it!). The star itself will act as a flashlight, whose dimming will inform us about the properties of the material orbiting the planet. Detecting such circumplanetary dust could provide insight into how and what kinds of exomoons form. These moons could be future places to search for life.

Progress
: The bRing/Siding Springs experiment was completed in the Department of Physics & Astronomy (Bausch & Lomb building) at University of Rochester in May and installed on site at Siding Springs Observatory, New South Wales, Australia in early-July (below). bRing/Sutherland is currently installed and going through initial testing. Photos of bRing UR in progress are attached to this page. A blog maintained by Lomberg (http://blaine.saao.ac.za/) documents the installation of bRing in Sutherland.
Cover Photo, Image may contain: outdoor and nature
Acknowledgments: The UR bRing experiment was completed with support from a University of Rochester University Research Award. Samuel Mellon is supported by funding from the DoD SMART scholarship program  (previously the NASA NExSS program). We would like to thank Mark Paup, Dave Mellon, and Ray Miller and the Zippo Tool Room staff from Zippo Manufacturing Company for donating their time and materials for some of the small parts manufacturing. We would also like to thank Joe and Debbie Bonvissuto from Freight Expediters for donating their time and service to bring in the outer bRing shell from the Netherlands.
ą
Samuel Mellon,
Jan 25, 2017, 9:32 AM
Ċ
Samuel Mellon,
Mar 7, 2018, 9:14 AM
ą
GPSbase.JPG
(1781k)
Samuel Mellon,
Feb 1, 2017, 7:41 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:32 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
Ċ
Qual.pdf
(4812k)
Samuel Mellon,
Feb 24, 2017, 6:44 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
ThumbsUp.JPG
(1849k)
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:33 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:40 AM
ą
Samuel Mellon,
Jan 25, 2017, 9:32 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:40 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:41 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:41 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:41 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:41 AM
ą
Samuel Mellon,
Feb 1, 2017, 7:41 AM
Comments