Get Ready: 2015A Is Upon Us

The MagAO team is in the final stages of preparations for 2015A — Laird, Katie, and Jared depart for Chile this coming Saturday. We’re going down early to do some work on Clio and replace a motor. By the time we come home, nearly 7 weeks will have passed.

Our preparations have included laying in a winter’s worth of wasabi peas.

We have a highly unreliable supply chain when we are on MagAO ops. So we have to look out for ourselves. This is what 10 lbs of wasabi peas looks like. We’ll see how customs goes.

Over the next 2 months you can look forward to at least one post a day, from your favorite MagAO bloggers, including KT, Jared, Alycia, Kate, Kim, TJ, Jordan, and distinguished guest bloggers such as Hernan, Gabriel, Mauricio, and Alberto. It’s possible that we’ll have an occasional picture of a Viscacha or two. Also, we’ll make fun of Laird. A lot.

Now, speaking of bloggers, we’re adding a few rules regarding the “Post of the Day”. These are designed to add a little creative flair to the musical selections. Here are the new regulations:

MagAO Blog Song Of The Day Rules For 2015A
1) All posts of the day (posts with a Day X in the title) must contain a song of the day. Posts which do not comply are subject to arbitrary, punitive, and likely embarassing editing by anyone else with a password.
2) All songs posted must also be posted with a cover or remake of said song if it exists anywhere on the internet.
   a) A version of the song by the same artist, i.e. live or acoustic, does count technically, but does not meet the spirit of this requirement. Abuse of this leniency will be reviewed if necessary.
   b) Re-mixes (i.e. by a DJ) also count in a technical sense. Bloggers are expected to use their judgement as to whether substantial interpretive value is added by the re-mix.
   c) A derivative work which merely samples or uses the sound-and-feel of the prior work does not count
      c.1) An extrapolation of 2.c is that Blurred Lines can not be posted at any time for any reason.
   d) Parodies count (except for parodies of Blurred Lines).
      d.1) If a Weird Al parody exists, it does not meet this requirement.
      d.2) However, if the song has a Wierd Al parody, it *must* be posted, excepting Weird Al parodies of Blurred Lines (see Word Crimes).
      d.3) Songs generally felt to be self parodies (cf. Macklemore) must still have a second version posted.
   e) Covers by Chris Daughtry do not meet this requirement.
      e.1) However, if the song has been covered by Chris Daughtry, said cover *must* be posted.
      e.2) Though none is known to exist, a cover of Blurred Lines by Daughtry is still subject to rule 2.c.1 above.
   f) Though none is known to exist, should one be produced prior to the end of 2015A any musical production featuring both Weird Al and Chris Daughtry will not be subject to this rule, and can be posted by itself. Even if it is Blurred Lines.
   g) The intent of this rule is not to restrict choices to popular songs. If no second version exists, for instance in the case of a musical score from a soundtrack, then this rule does not apply. However, note that the MagAO team will be up all night, every night, for ~40 consecutive nights. That’s a lot of time to search the internet. You had better be sure (see rule 1).

To illustrate the proper way to post a song of the day, I present the following:

Beginning with the actual song (note the Family friendly version is preferred):

I hate that version. When I hear the song, I think it should sound more like this:

You aren’t restricted to one cover of course. Here’s another good one, which is also a hint at how to win the “best poster of cover songs” award.

The following is required for compliance (though it could be used multiple times in the coming months):

Finally, the following two videos help us illustrate the difference between a cover song and a parody video. This is a funny video with a cover song:

This is a parody video, not a parody song, and as such, does not meet the requirements above:

New Coronagraphs for 2015B (and 2015A)

We have just finished designing, and are fabricating, new vector apodizing phase plate (APP) coronagraphs for Clio2. We plan to install these during the last week of April, 2015, prior to the 2015A run. We will be commissioning and characterizing them at the beginning of the run. They will be available for observations on a shared-risk basis during 2015A and 2015B. In addition to the usual authorship procedures for MagAO, during 2015A and 2015B any observations with the APPs will include our collaborators at Leiden Observatory (6 additional authors) who have led the development this new type of APP.

The major improvment over previous generations of APPs is the use of liquid crystal technology, and the exploitation of polarization to allow 360 degree observations. We are procuring two new optics.

vAPP A: the first of the new vAPPs is designed to work at 2 lambda/D, with raw contrasts of 1e-5 or better out to roughly 1 arcsecond. This device will work from Ks to M’. We expect best performance in narrow filters. By splitting the beam with a half waveplate integral to the APP, two opposite dark holes are created. Here we show predicted raw PSF contrast including contamination from the other PSF. The simulated image shows the notional layout of the 2 vAPP PSFs on the Clio2 detector, at two different nod positions. All calculations shown here are by Gilles Otten at Leiden. NOTE: these calculations do not model effects such as non-common-path aberrations, residual wavefront errors, and various pupil features. On-sky performance will be worse than shown here.

Contrast at 90 degrees (middle of dark hole)
Contrast at 90 degrees (middle of dark hole)
Contrast at 140 degrees.
Contrast at 140 degrees.
Contrast at 170 degrees.
Contrast at 170 degrees.
Simulated vAPP PSF at 3.9 microns.
Simulated vAPP PSF at 3.9 microns.

vAPP B: the second device is primarily a technology demonstrator. It actually has two masks on one substrate. One mask will test a new fully 360 dark hole. The other mask will test using an APP for focal plane wavefront sensing.

Experimental 360 degree vAPP PSFs.
Experimental 360 degree vAPP PSFs.

New Results In The Chamaeleon

Now that the MagAO team has (mostly) recovered from our epic 6 week stay at LCO, we are turning our attention to processing all of the great data we’ve been taking. We’re also happy to announce two new publications based on MagAO data which have been accepted to the Astrophysical Journal, both of which looked at stars in the constellation Chamaeleon.

Ya-Lin Wu has been studying the young star CT Cha with VisAO. You can read about his results here.

Steph Sallum used Clio2, in combination with some other instruments, and used a resolution-boosting technique called non-redundant masking to take a look at T Cha. You can find out about her results here.

We have a bunch of other papers in the works, and we’re already starting to plan for our next run, which starts May 3rd. Stay tuned!

New Spatially Resolved Observations of the T Cha Transition Disk and Constraints on the Previously Claimed Substellar Companion

orbital
χ2 slices at the fixed contrast ratio for all L observations as well as 2013 NaCo Ks observations, with filled contours at 1 to > 4σ confidence limits. The line indicates a circular orbit in the plane of the outer disk. The ×s show the initial position of the putative companion from our re-reduction of the 2010 NaCo L data, while the circles show the predicted position(s) of a planet on the orbit. We plot two since the planet could be orbiting in either direction.

Abstract: We present multi-epoch non-redundant masking observations of the T Cha transition disk, taken at the VLT and Magellan in H, Ks, and L’ bands. T Cha is one of a small number of transition disks that host companion candidates discovered by high-resolution imaging techniques, with a putative companion at a position angle of 78 degrees, separation of 62 mas, and contrast at L’ of 5.1 mag. We find comparable binary parameters in our re-reduction of the initial detection images, and similar parameters in the 2011 L’, 2013 NaCo L’, and 2013 NaCo Ks data sets. We find a close-in companion signal in the 2012 NaCo L’ dataset that cannot be explained by orbital motion, and a non-detection in the 2013 MagAO/Clio2 L’ data. However, Monte-carlo simulations show that the best fits to the 2012 NaCo and 2013 MagAO/Clio2 followup data may be consistent with noise. There is also a significant probability of false non-detections in both of these data sets. We discuss physical scenarios that could cause the best fits, and argue that previous companion and scattering explanations are inconsistent with the results of the much larger dataset presented here.

Sallum, S., et al. “New Spatially Resolved Observations of the T Cha Transition Disk and Constraints on the Previously Claimed Substellar Companion”
ApJ, 801, 85, 2015     arxiv preprint

New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System

CT Cha in MagAO filters. Image contrasts are adjusted to bring out the objects.
Top row: unsaturated dataset showing the PSF. Middle row: reduced, saturated dataset
before any halo subtraction. Bottom row: primary’s halo removed by subtracting a rota-
tionally symmetric PSF.

Abstract:
We used the Magellan adaptive optics (MagAO) system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r’, i’, z’, and Ys. With our new photometry and Teff~2500 K derived from the shape of its K-band spectrum, we find that CT Cha B has Av = 3.4+/-1.1 mag, and a mass of 14-24 Mj according to the DUSTY evolutionary tracks and its 1-5 Myr age. The overluminosity of our r’ detection indicates that the companion has significant Halpha emission and a mass accretion rate ~6*10^-10 Msun/yr, similar to some substellar companions. Proper motion analysis shows that another point source within 2″ of CT Cha A is not physical. This paper demonstrates how visible wavelength AO photometry (r’, i’, z’, Ys) allows for a better estimate of extinction, luminosity, and mass accretion rate of young substellar companions.

Wu, Y.-L., et al. “New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System”
ApJ, 801, 4, 2015      arxiv preprint