Final Update

As anyone following the observing campaign will realise, it has not gone quite as expected… The lightcurve remains flat and without any hint of the ~30%-deep eclipse we predicted. 

To be frank, we got it wrong. We can now say that the eclipses seen in 2008 & 2011 around PDS 110 were not made by a periodic object, or at least, not one with dust that stuck around over 6 years. And we can say that thanks to the many fantastic observations from amateur and professional observers alike! So thanks very much for that.

The plan from here on out:

Professional observers: We can no longer expect you to contribute data. I’m sure your telescopes have other, more important targets that can be observed. Professional survey telescopes such as ASAS-SN will of course continue to monitor the star.

AAVSO: Voluntary amateur observations of the star will, we hope, continue. We still know this star has random (and probably aperiodic) eclipses which would be fantastic to observe again. 

The paper: There will be a paper, submitted in the next couple of months, detailing the lightcurves and the null result. All significant contributors of data will receive co-authorship. For professional observatories, this includes the list of original contributors to the facility (I will chase these up once I have the data).

Data: Rather than re-reducing many disparate image sets, we request reduced photometry. Either uploaded to AAVSO, to the google doc, or by email. Please upload photometry in the next couple of weeks, so we can analyse the whole dataset together!

What did cause the eclipses is still somewhat unclear, and I’m sure the observations taken have improved our knowledge of this mysterious young star greatly.

Once again, thanks for your contributions. Thanks especially to the largest AAVSO observers – G. Myers, C. Lopresti, J. Hambsch, U. Quadri & M. Deldem. And professional contributors M. Mallonn, J. McCormac, R. Sfair & A. Scholz.

Clear skies,

Hugh Osborn

What is it?

PDS 110 is a young star in Orion. We see evidence that a dust-enshrouded body eclipsed the star in 2008 & 2011, and believe it will do so again in September 2017, and we need you to help us monitor it!

  • Young – only ~10Myrs old
  • Bright – Magnitude 10.45 in V-band
  • F-type star, with 2.2 solar radii and 1.7 solar masses
  • Hosts a large circumstellar ring
  • Simbad link
  • Extremely similar dips in 2008 & 2011
  • Duration: 16±5 d and Depth: 26±6%
  • Suggest an orbital period of 808±2 d
  • Shearing makes loose dust clump an unlikely explanation
  • Next predicted eclipse: Sept 9th – 30th 2017
  • A dust cloud ~0.3 au in diameter
  • Dust held together by gravity of an unseen secondary with mass from 1.6-68 MJup 
  • Sharp gradients seen in eclipse may be due to moon-forming exorings around the body
  • Or, it may be aperiodic dimmings due to dust around the star
Read the paper (arXiv:1705.10346)

PDS 110 discovery data (with WASP and KELT)

How to help

We need astronomers across the world to detect and study the eclipse of PDS 110!

If you have:
● A telescope - amateur or professional
  • 200mm (7″) to 1m (40″) is ideal.
  • Having a CCD & being robotic both help!
  • (Almost) any location!
● Knowledge o​​​​f photometry / reduction
  • Minimal experience needed, but we will ask observers to process their own data
Then you may be able to help us!

We are teaming up with the American Association of Variable Star Observers (AAVSO) to coordinate the observations.

Why we need you

We have reason to believe that there is sharp structure in the eclipsing material.

This may even be exo-rings aroung a young exoplanet (similar to the eclipse of J1407, modelled on the right).

However, because of the position of PDS110, we cannot observe the brightness of the star for more than 3 hours from a single location.

Only with multiple observers can we achieve the near-continuous photometry needed to map this elusive object!

Observing PDS 110

Where to look

RA: 05 23 31.0105 ;   Dec: -01 04 23.702

AAVSO have finder charts with lists of good comparison stars available

Orion (and PDS 110) is observable across the world for between 1 and 3 hours before dawn each morning.

When to look

We expect central eclipse to be around 14th of September (plus or minus one week).

The eclipse will (if it happens) lasts ~16 days

That means we need measurements throughout September 2017

How to look (observing strategy)

This is up to you! 

Until a dip begins, one or two measurements per night is sufficient. If and when the eclipse starts, we may ask for increased cadence (sign up below for “triggered” email alerts).

If multiple filters are available we ask for broadly spaced filters (eg, B & R; B,V & z’, etc.)



Joining the Campaign

We are primarily using the AAVSO campaign to coordinate observations, and expect photometry to be submitted through the AAVSO WebObs tool.

Significant contributions of data to the campaign will be given co-authorship on the follow-up paper.

If you want to hear more about the campaign, receive triggered email alerts if & when the eclipse begins, join our Slack channel for organisation, or join our google spreadsheet of photometry (for AAVSO-free data uploads), then please sign up below: