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EXPRES

Yale Astronomy

Monsoon Season 2019

Aug 23, 2019 - Debra Fischer

The Lowell Observatory Discovery Channel Telescope (DCT) was shut down from July 8 to August 7 because of the seasonal monsoons in Arizona. We were supposed to begin observing on August 9, but the observatory was hit twice by lightening, wiping out the surge protection for all observatory instruments (what's that saying about lightening never striking the same place twice?). This slowed us down for a couple of days as we went into safety mode, but by August 13, we were back on sky with all systems go!

The shutdown gave us a welcome opportunity to catch up on a lot of work. On July 1, we had a catastrophic failure of the laser comb [1, 2, 3]. Luckily, Tilo Steinmetz had serendipitously arrived that same night from Menlo Systems in Germany for planned maintenance work on the comb. He spent three days repairing the motor for the reference switch, cleaning the fabry perot cavities, and swapping in a new photonic crystal fiber (PCF). The result of his work is a flat comb [4] that is performing beautifully.

We made a decision to shift the bandwidth of the comb to redder wavelengths to increase the lifetime of the PCF. To calibrate the blue wavelengths, we are collaborating with Andy Szentgyorgyi and David Phillips at Harvard. They are loaning us an etalon that will cover the blue wavelengths, supplementing the LFC. This will give us time to apply for funding for our own etalon as a permanent solution. We also made progress writing papers that are about to be submitted and rolled out several software upgrades.

We are warrier scientists. With stubborn persistence and team work, we have beaten one challenge after another to finally reach this point. What keeps us going is the thrill of discovery and we have some exciting new results:

  1. We are making real progress in reducing "red noise" - the photospheric velocities that add confusing noise to our data. This work was done with funding from the NSF ("Planet Whisperer") and NASA ("Extreme RV Precision: Separating Stellar Jitter from Orbital Velocities") with Prof Eric Ford (Penn State) and Prof Jessi Cisewski (Yale, Statistics and Data Science) and all of our postdocs and students. This progress will allow us to pull back the curtain of noise in the search for Earth-like planets. For most of my career, I have been told that this couldn't be done. We are doing it now!
  2. Our velocity precision on stars is now better than 20 centimeters per second at a signal-to-noise of 300. This is a factor of 5 improvement over the state of the art a year ago. After fitting for known planets in 55 Cnc, the residual scatter is about 60 centimeters per second and we will apply the methods mentioned above to further improve this. Look at the comparison of 1500 archival data points for 55 Cnc e spanning 20 years (Bourrier et al. 2018) with 14 nights of EXPRES data. [5]

It is worth noting that the discovery of new planets does not relieve our responsibility to care for Earth, "the only home we've ever known" (Carl Sagan). We are not looking for new planets because we expect to relocate. The Earth is running out of time. Global warming is caused by human activities and it must be addressed now; where now is today, this week, this year. If we do not aggressively combat climate change now, our habitat will be seriously compromised for hundreds of years and unable to support the diversity of life on Earth today. It is heartbreaking to watch [6, 7, 8] and difficult to understand the greed and willful ignorance that surrounds this issue. Please join scientists and informed citizens in fighting this imminent threat. A good place to start is to campaign and vote for thoughtful politicians who will prioritize climate change now. We all need to modify the overconsumption that typifies our lifestyles. We can do this by making wise, controlled, preemptive choices or we will have painful changes chaotically forced upon us. Ignoring climate change is not an option - it is time to go to battle for planet Earth.

August 23, 2019 Slideshow

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PCF fiber in the LFC begins to fail, 14 Jun 2019
Catastrophic failure of the PCF fiber in the LFC; beginning of the night on July 1, 2019
Catastrophic failure of the PCF fiber in the LFC; end of the night on July 1, 2019.
July 4, 2019: Refurbished LFC with a new PCF.
Before and after: 1500 Archival RVs over 20 years (Bourrier et al. 2018) vs 100 EXPRES RVs over 14 nights in Spring 2019 (Ong et al. 2019)
 A global emergency - there is no Planet B for us. Please act now.
A global emergency - there is no Planet B for us.
A global emergency - there is no Planet B for us.

About Us

DCT_lowell
Photo from Lowell Observatory

The EXPRES team works on the discovery of planets orbiting stars other than our Sun, or exoplanets.

EXPRES is a next generation spectrograph that aims to break the record on current measurement precision with the goal of detecting small, rocky planets - similar to Earth - orbiting nearby stars. The instrument blends high resolution and extraordinary stability to produce the highest fidelity data.

This journey began long ago; our hope is that EXPRES will help humanity to explore the unknowns in the galaxy.

EXPRES is possible thanks to...


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EXPRES Cast and Crew

  • Professors
    • Debra Fischer, Astronomy
    • Jessi Cisewski, Statistics
    • John Michael Brewer, SFSU
  • Research Scientists
    • Andrew Szymkowiak
    • Colby Jurgenson
    • Tyler McCracken
    • David Sawyer
  • Postdoctoral Associates and Fellows
    • Rachael Rottenbacher
  • Graduate Students
    • Allen Davis
    • Ryan Blackman
    • Ryan Petersburg
    • Lily Zhao
    • Joel Ong
  • Undergraduate Students
    • Christopher Leet
    • Yonatan Zeff
    • Abby Mintz
  • Collaborators
    • Sally Dodson-Robinson, University of Delaware
    • Lars Buchhave, Danish National Space Institute
    • Gregory Henry, Tennessee State University
  • We Would Like to Expressly Thank
    • Steve Girvin, Yale University
    • Pieter van Dokkum, Yale University
    • Gábor Fűrész, MIT
    • Andy Szentgyorgyi, Harvard
    • Francesco Pepe, Geneva Observatory
    • Matteo Genoni, Brera Astronomical Observatory
    • Giorgio Pariani, Brera Astronomical Observatory
    • Marco Riva, Brera Astronomical Observatory
    • Ben Hardesty, Lowell Observatory
    • Frank Cornelius, Lowell Observatory