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Yale Astronomy

CHIRON Spectrometer

The Yale exoplanet group, together with Andrei Tokovinin at CTIO, designed and built the CHIRON spectrometer. The initial commissioning was in January 2011; after upgrades that took place from October to May 2012, the spectrograph was recommissioned in July 2012. This instrument was funded by the NSF MRI program to PI Fischer with funding from the American Recovery and Reinvestment Act (ARRA). Observing time on CHIRON is available through the SMARTS consortium or through NOAO proposals.

Please cite Tokovinin et al. 2013 on publications and posters that make use of CHIRON spectra.

CHIRON is a fiber-fed Echelle spectrometer, that replaced the Echelle at the 1.5m SMARTS telescope in Chile with greatly enhanced throughput. Spectral resolution R=90,000 is achieved with an image slicer, however a R=90,000 and R=136,000 slit mask (that incurs larger light losses) is also available. The optical and optomechanical design combines critical parts developed in house with commercial components, in order to keep the cost reasonable while achieving high performance. After commissioning data showed that the RMS velocities for the stable star, Tau Ceti, were about 2 m/s - not "good enough." The team brainstormed to come up with a list of upgrades to improve the stability of the instrument.

From left to right: Christian Schwab, Andrei Tokovinin, Julien Spronck

We upgraded CHIRON with a new echelle grating in a vacuum enclosure, sol-gel coating of the large optics, an exposure meter for photon-weighted midpoint times (to make precise barycentric corrections), an octagonal fiber feed, staged temperature control of the instrument, extensive monitoring of pressure and temperature, nightly quality control reports (checks of FITS header information and spectral information). These upgrades collectively improved the stability of the instrumental profile and the velocity precision. Our new Doppler measurements of the stable star, Tau Ceti, showed RMS of 0.5 m/s over 10 nights after commissioning. This low RMS is observed in other ~2 week data sets, but we also see longer term low amplitude variations that could arise from the star, orbiting planets, or instrumental stability.

Analysis by D. Fischer
CHIRON is now being used to carry out to a high-cadence search for low mass planets around Alpha Centauri A and B and other stars in the southern hemisphere.

Technical documents for the CHIRON spectrometer can be found on Andrei Tokovinin's site.

Some CHIRON publications:

  1. Giguere, M. J., Fischer, D. A., Zhang, C. X. Y., Matthews, J. M., Cameron, C., Henry, G. W. 2016, "A combined spectroscopic and photometric stellar activity study of Epsilon Eridani with MOST and CHIRON"(accepted ApJ Jun 2016)
  2. Richardson, N. D., Madura, T. I., St-Jean, L., Moffat, A. F. J., Gull, T. R., Russell, C. M. P., Damineli, A., Teodoro, M., Corcoran, M. F., Walter, F. M. 2016, "To Infinity and beyond! The He I absorption variability across the 2014.6 periastron passage of eta Carinae" arXiv160603655
  3. Jones, M. I., Jenkins, J. S., Brahm, R., Wittenmyer, R. A., Olivares E., F., Melo, C. H. F., Rojo, P., Jordan, A., Drass, H., Butler, R. P., Wang, L. 2016, "Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars"A&A, 590, 38
  4. Kane, S. R., Wittenmyer, R. A., Hinkel, N. R., Roy, A., Mahadevan, S., Dragomir, D., Matthews, J. M., Henry, G. W., Chakraborty, A., Boyajian, T. S., Wright, J. T., Ciardi, D., Fischer, D. A., Butler, R. P., Tinney, C. G., Carter, B. D., Jones, H. R. A., Bailey, J., O'Toole, S. J. "Evidence for Reflected Light from the Most Eccentric Exoplanet Known"ApJ, 821, 65
  5. Jones, M. I., Jenkins, J. S., Rojo, P., Olivares, F., Melo, C. H. F. 2015, "Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP 67851c" A&A, 580, 14
  6. Ratajczak, M., Helminiak, K. G., Konacki, M. 2015, "Studies of Long Period Eclipsing Binaries"ASPC, 496, 311
  7. Mennickent, R. E., Djurasevic, G., Cabezas, M., Cseki, A., Rosales, J. Niemczura, E., Araya, I., Cure, M. 2015 "A spectroscopic and photometric study of the interacting binary and double period variable HD 170582"ASPC, 496, 175
  8. Feiden, G. A.; Stempels, E.; Hebb, L.; Mack, C. E., III; Chaboyer, B. 2015, "Spectroscopic Study of the Low Mass Benchmark Eclipsing Binary UV Piscium" ASPC, 496, 174
  9. Mehner, A., Davidson, K., Humphreys, R. M., Walter, F. M., Baade, D., de Wit, W. J., Martin, J., Ishibashi, K., Rivinius, T., Martayan, C., Ruiz, M. T., Weis, K. 2015, "Eta Carinae's 2014.6 spectroscopic event: Clues to the long-term recovery from its Great Eruption"A&A, 578, 122
  10. Waisberg, I. R., Romani, R. W. 2015, "Echelle Spectroscopy of Gamma-ray Binary 1FGL J1018.6-5856"ApJ, 805, 18
  11. Mennickent, R. E., Djurasevic, G., Cabezas, M., Cseki, A., Rosales, J. Niemczura, E., Araya, I., Cure, M. 2015 "A spectroscopic and photometric study of the interacting binary and double period variable HD 170582"IAUS, 307, 125
  12. Shore, S. N. (and 16 co-authors) 2014 "First high resolution ultraviolet (HST/STIS) and supporting optical spectroscopy (CHIRON/SMARTS, HRS/SALT) of V1369 Cen = Nova Cen 2013"ATel, 6413, 1
  13. Rittipruk, P., Yushchenko, A., Kang, Y. W. 2014, "Spectroscopic Analysis of Planetary Host Stars"ASPC, 482, 9
  14. Jones, M. I., Jenkins, J. S., Bluhm, P., Rojo, P., Melo, C. H. F. 2014, "The properties of planets around giant stars"A&A, 566, 113
  15. Brewer, J. M., Giguere, M., Fischer, D. A. 2013, "CHIRON TOOLS: Integrated Target Submission, Scheduling and Observing Systems for a High-Resolution Fiber-Fed Spectrograph"PASP, 126, 48
  16. Ratajczak, M., Heminiak, K. G., Konacki, M., Jordan A. 2013, "Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - V. Investigation of subgiants and giants: the case of ASAS J010538-8003.7, ASAS J182510-2435.5 and V1980 Sgr"MNRAS, 433, 2357
  17. Shore, S. N., De Gennaro Aquino, I., Schwarz, G. J., Augusteijn, T., Cheung, C. C., Walter, F. M., Starrfield, S. 2013, "The spectroscopic evolution of the Gamma-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae" A&A 553, 123
  18. Tokovinin, A. 2013, "Kappa Fornaci, A Triple Radio Star" AJ, 145 76
  19. Tokovinin, A., Fischer, D. A., Bonati, M., Giguere, M. J., Moore, P. Schwab, C., Spronck, J. F. P., Szymkowiak, A. 2013 "CHIRON - a Fiber Fed Spectrometer for Precise Radial Velocities" PASP, 125, 1336
  20. Schwab, C., Spronck, J. F. P., Tokovinin, A., Szymkowiak, A., Giguere, M., Fischer, D. A. 2012, "Performance of the CHIRON high-resolution Echelle spectrograph" SPIE 8446