Cosmic Diary Marchis

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Flying through the binary trojan asteroid system (617) Patroclus

11 hours 28 min ago

Another day, another video!

This time I am posting a video of the binary L5 Trojan Asteroid (617) Patroclus-Menoetius. In collaboration, with the team at the California Academy of Sciences, we have created a model of this interesting binary asteroid system which shares its orbit with Jupiter.

In 2001, a group of astronomer discovered that the L5 Trojan asteroid (617) Patroclus is in fact made of two components. In 2006, using Laser Guide Star Adaptive Optics System at W.M. Keck Observatory, we showed that those two components orbit around the center of mass of the system in ~4 days at 680 km describing a circular orbit. We named the second component Menoetius, the argonaut father of Patroclus in the greek mythology.

From the estimate of the size (derived from various techniques including Spitzer observations of mutual events taken in 2010 and stellar occultation on October 2013), we found out that the components are less dense than icy water, with a grain density very close to satellites of giant planets (like Amalthea, moon of Jupiter).

The Binary Trojan Asteroid (617) Patroclus-Menoetius from Franck Marchis on Vimeo.

Because Patroclus has a different color and density than (624) Hektor, we speculated that it could be a captured Jupiter-Saturn asteroid which ended up in the gravitational well of the Sun-Jupiter system during the migration of the giant planets 3.7 Billion years ago. Its binary nature could be the result of tidal disruption when primitive asteroid had a close encounter with Jupiter before the capture.

Ultimately, we will need to send a spacecraft there to really understand this system. NASA has pre-selected the LUCY new discovery mission which could flyby this binary Trojan asteroid in 2033.

Clear Skies,

Franck M.

Visiting the L4 Trojan Asteroid (624) Hektor

May 23, 2016

I finally started uploading some of the animations of the talk that I gave last month at the California Academy of Sciences. Today let’s watch (624) Hektor, the binary and bilobed largest Jupiter-Trojan asteroids. This is a puzzling multiple asteroid system with a lot of mysteries (eccentric and inclined orbit of the moon, complex shape and structure for the primary, …). 

Our study based on AO observations collected over 8 years was published in 2014. The conclusion of our work is that 624 Hektor is probably a captured Kuiper-belt object and the moon formed a long time ago from the slow velocity encounter of the components.

The Largest Jupiter Trojan: 624 Hektor and its moon from Franck Marchis on Vimeo.

We will probably need to send a spacecraft over there to really understand this complex mini-geological world. The good news is that several space agencies, including JAXA and NASA, are thinking about that.

 

I would like to thank to my colleague Josef Durech,  Matija Ćuk, Julie Castillo, Frederic Vachier, Jerome Berthier and numerous more for their long-term contribution to this project. I also should include my sister Helene Marchis for making the first drawing of this system. Thanks as well to the California Academy of Sciences for making those great CGI videos and the director Ryan Wyatt for inviting me.

Clear skies,

Franck M.

Gravitational wave detection rumors may end on Feb 11

February 08, 2016

It is official. NSF, together with scientists from Caltech, MIT and the LIGO collaboration will give an update on their effort to detect gravitational waves.

What is LIGO? Check out this article published in Arstechnica by Eric Berger.

I am not going to speculate on the announcement and will simply wait for it. Joe Giaime a California Institute of Technology physicist who manages the lab and also a professor at Louisiana State University was pretty clear in the Arstechnica interview about the way this group works: “We’re really kind of old school,” he said. “We analyze our data. If there’s anything interesting we write it up in papers. We send the papers to the journals. If and only if there’s an interesting discovery that passes muster, and it has been accepted for publication by a journal, then we blab about it. Anything before that, you’re not going to get anything out of me.”

So if they indeed have detected those gravitational waves, we will also get a paper.

Computer simulation of a black hole collision. When two black holes merge into one, enormous amounts of energy are released in the form of gravitational waves.

Below the official announcement.

THE FOLLOWING ITEM WAS ISSUED JOINTLY BY THE CALIFORNIA INSTITUTE OF TECHNOLOGY IN PASADENA, THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY IN CAMBRIDGE, AND THE NATIONAL SCIENCE FOUNDATION IN ARLINGTON, VIRGINIA, AND IS FORWARDED FOR YOUR INFORMATION. FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE AMERICAN ASTRONOMICAL SOCIETY.

8 February 2016

** Contact details appear below. **

SCIENTISTS TO PROVIDE UPDATE ON THE SEARCH FOR GRAVITATIONAL WAVES THURSDAY

** Synopsis: 100 years after Einstein predicted the existence of gravitational waves, the National Science Foundation gathers scientists from Caltech, MIT, and the LIGO Scientific Collaboration to update the scientific community on efforts to detect them. **

Journalists are invited to join the National Science Foundation as it brings together scientists from Caltech, MIT, and the LIGO Scientific Collaboration (LSC) this Thursday at 10:30 a.m. EST (15:30 UTC/GMT) at the National Press Club for a status report on the effort to detect gravitational waves — or ripples in the fabric of spacetime — using the Laser Interferometer Gravitational-wave Observatory (LIGO).

This year marks the 100th anniversary of the first publication of Albert Einstein’s prediction of the existence of gravitational waves. With interest in this topic piqued by the centennial, the group will discuss their ongoing efforts to observe gravitational waves.

LIGO, a system of two identical detectors carefully constructed to detect incredibly tiny vibrations from passing gravitational waves, was conceived and built by MIT and Caltech researchers, funded by the National Science Foundation, with significant contributions from other U.S. and international partners. The twin detectors are located in Livingston, Louisiana, and Hanford, Washington. Research and analysis of data from the detectors is carried out by a global group of scientists, including the LSC, which includes the GEO600 Collaboration, and the VIRGO Collaboration.

When:

Thursday, Feb. 11, 2016

10:30 am US EST (7:30 am US PST, 15:30 UTC/GMT)

Where:

The National Press Club

Holeman Lounge

529 14th Street NW, 13th Floor

Washington, DC 20045

Media RSVP:

Seating is extremely limited, but an overflow room will be available where reporters can still ask questions and have access to additional subject matters to interview after the press conference. Only the first 50 journalists to arrive will be seated in the main room. All interested journalists should RSVP to any of the media contacts listed below to ensure press credentials are prepared ahead of time. A mult box will be available for broadcast media, and the Press Club is equipped with wireless access.

Live Webcast:

For press not based in the Washington, D.C. area, this event will be simulcast live online, and we will try to answer some questions submitted remotely. For details about how to participate remotely, please contact anyone listed below.

Contacts:

Tom Waldman

Caltech

+1 (626) 395-5832, cell: +1 (818) 274-2729

twaldman@caltech.edu

Kimberly Allen

MIT

+1 (617) 253-2702, cell: +1 (617) 852-6094

allenkc@mit.edu

Ivy Kupec

NSF

+1 (703) 292-8796, cell: +1 (703) 225-8216

ikupec@nsf.gov