No Halleymites in the Main Belt!

Today we have a guest post by Comet Hunters volunteer Peter Jalowiczor.

Peter Jalowiczor (left) with MSAS Chairperson Les Marsden (right)

I enjoy trawling through quality old vinyl to buy, and sometimes real gems can be found such the one I came across recently to my amazement (and some amusement): a 7“ vinyl single commemorating the return of Halley’s Comet in 1986 with a children’s book feel to the cover…

Yes, we’re real Halleymites from the Comet Halley and Yes, You’ve never heard of us before but we’ve been around the Galaxy for thousands of years…

How prophetic. I certainly have never heard of them. At the time Comet Halley came around in 1986, I was a first year Physics Student at the University of Sheffield. This astronomical event was big news. A few years later, I would engage in a slice of Postgraduate research for P/ Halley  under one of the academic staff who was a World expert in his field at the time.

But the Halleymites somehow kept quiet…

The Talk

Over thirty years later and we have Comet Hunters; it is a project I have contributed towards alongside other Zooniverse projects (mainly P4). By classifying images whenever there were a few minutes. Recently, I had the opportunity of collating materials from Comet Hunters for a talk to be given at my local Astronomical Society: the MSAS (the Mexborough and Swinton Astronomical Society). The society is situated ~20km from Sheffield (pop, 570,000), England and was founded in 1978.  Every Thursday evening is a social occasion centred on a lecture.  Members, such as me are encouraged to give talks. Usually about once a month, an academic visits the society to present on an aspect of Astronomy.

The evening was divided-up into four parts:

1. Q & A from the Planet Four talks at MSAS
2. Presentation – based largely on the blogs Peter Jalowiczor
3. Presentation – material kindly provided by Meg Schwamb
4. Q & A on the Comet Hunters’ Presentations

Q & A from the Planet Four talks at MSAS

This was a chance to review the Q & A to make sure anyone, who had missed these questions posted on the P4 blog

II.& III.    The Presentations

Started with an introduction to Comet Hunters as a citizen science project. The project was initiated to greatly increase the discovery rate of these objects. The first such object was found in 2006 and there are only 12 known at present.

This followed with a discussion about Asteroids and Comets with the distinct examples of Gaspra and Halley being given in these categories. However, where do we draw the distinction between these objects? Comets were always assumed to have come from the outer Solar System beyond the orbit of Neptune. Asteroids have generally thought to be from the Main Belt.

Next came a discussion of the two different searches: the HSC Survey or the Archival Data Search.  A discussion of the instruments: Suprime Cam and the Hyper Suprime-Cam used in the search for these objects.

The Subaru telescope – this also included Meg’s detailed description about life for Astronomers at this wonderful observatory; one of the best observing sites in the World. The difficulties experienced by Astronomers at such high altitudes over 4,600m asl. Anyone working at the summit of Mauna Kea cannot stay up longer there longer than 14 hours needing to descend to mid-altitude for safety and health reasons. Sandwiches left for more than 20 minutes become stale giving all the water to the air (as the one left by Meg). This prompted one of the members to jokingly suggest Rhyita might be a better option next time.  Another of the society members (not present) has travelled the world specifically visiting observatories and had the privilege of visiting the observatory in 2012 at the time of the transit of Venus.

Conclusions

• Hyper Suprime-Cam search launched in June 2016.
• 0ver 8,000 volunteers have contributed to the project to varying degrees, inspecting HSC for main belt comets.
• 4,877 main belt asteroids located in the HSC wide survey fields have been searched for cometary activity.
• Assuming a detection efficiency of 20% an upper limit of 1% is placed for the occurrence rate of MBCs in each of the sample of asteroids.
• Simulated MBC observations are planned to measure the detection efficiency.

Q & A

A variety of questions were asked following the two presentations. The Comet Hunters science team will try and answer these questions in a following blog post.

• Snow Line – how exactly is the boundary of the snow-line worked out? What is its relevance? It seems that there is water (albeit in different forms) such as lots here on the Earth both inside and outside the snowline?

• Regarding the MBCs isn’t there a possibility that the surface ices over geological time would have sublimated from the outside (of the object)? We would then be left with ice at the centre perhaps covered with rock/dust?

• Classification: What is the point of the reference images: the ones to the right of the main image when we are really looking at the central object?

• What is the file size from the updated camera (i.e. Hyper Suprime-Cam)?

• In the charts showing the ‘Tail Visible in One of the Images’ and ‘Tail Visible in Two of the Images’ what exactly does this data represent?

The presentations certainly opened up some debate during and after the talks. A number of members noted that if we look at the current definition of Comets and Asteroids, there does not seem to be a clear boundary.  How would Enceladus fit in this category? After all, it is ejecting water.

On an ending note, I also think that it is safe to say that there are no Halleymites in the Main Belt…

Audience at the MSAS meeting