Presentation on theme: "The Habitable Zone Planet Finder A high-resolution NIR spectrograph for the Hobby Eberly Telescope Suvrath Mahadevan Pennsylvania State University Larry."— Presentation transcript:
The Habitable Zone Planet Finder A high-resolution NIR spectrograph for the Hobby Eberly Telescope Suvrath Mahadevan Pennsylvania State University Larry Ramsey, Alex Wolszczan, Jason Wright (PSU), Michael Endl (UT), Bo Zhao (UF), Stephen Redman (PSU) On behalf of the HZPF Team
Earths & Super Earths around M stars 1 m/s 0.1 m/s Kasting et al M dwarfs lower mass and lower luminosity. HZ is closer, Doppler amplitude of a terrestrial planet is upto 10x higher that that around a G2V star HZ.
Earths & Super Earths around M stars Recommendations to develop NIR Precision RV techniques from ExoPTF and Blue Dots ExoPTF Lunine et al. 2008
Earths & Super Earths around M stars Jones et al Mid/Late M stars are attractive targets since RV amplitude of terrestrial planets is so much higher than around F, G, K. Much beyond M4 are as yet unprobed by precision RVs.
NIR follow-up observations can be very helpful when claiming detection of planets around young/active stars (Prato et al. 2008) Setiawan et al Claimed detection of planet around the young active star TW Hya shown to be due to activity induced RV effects – Huelamo et al Precision RVs in the NIR
NIR follow-up observations very important to confirm ground based astrometric candidates around low mass planets Zapatero Osorio et al Precision RVs in the NIR Vb10 Pravdo & Shaklan 2009 V= 17.3, H=9.22
Pathfinder : One that discovers a new course or way, especially through or into unexplored regions. Penn State NIR Pathfinder spectrograph is a lab test bed to explore challenges in precision NIR radial velocities. Initial Motivation was to retire some of the risk in the Gemini PRVS proposal, which it succeeded in doing. Now going beyond to explore more of the fundamental issues in NIR velocity extraction. Pathfinder is a lab prototype build as a testbed from existing and available parts. Uncooled, not highly temperature stabilized, uses a H1 array that is sensitive to 2.7um, so background is high. Still a VERY useful way to test RV precision, extraction, calibration techniques etc in what is still a somewhat unexplored domain at ~3- 5m/s precision. Will focus on the fiber fed simultaneous calibration approach. Penn State
R~40,000 coverage of Y, J, H bands- few orders a time. Fiber slicing/modal noise issues tested
Penn State The Big Issues in Precision NIR RVs Detector Issues: NIR detectors not as well characterized for RV work and low noise as CCDs Calibration Issues: What wavelength/velocity calibration is best in the NIR? Telluric Lines!!!! Instrinsic Stellar noise Solar Light Th-Ar Lamp
Penn State: On Sky Performance Achieve 7-10m/s rms scatter on Sunlight with two different configurations and simultaneous Th-Ar calibration. Suggests detector issues like persistence and parasitic ghosting are not a killer at ~< 10m/s. This is short term stability. Solar daytime observations affected by clouds. Sun not a point source Ramsey et al Also ~6.5m/s stability results presented by Dreizler et al. with CRIRES + gas cell
The Big Issues Telluric Lines Calibration & Instrument Tracking NIR Detectors The Big Issues: Calibration Simultaneous Calibration with Th- Ar a logical option since obviously Th-Ar works in the visible to <1m/s NIR lineslists of Th-Ar made by Kerber et al 2008 for CRIRES No lack of Lines, issue is that Ar lines are much much brighter, and not as stable. Can sub-array readout with an NIR array, but still scattered light Frequency comb is certainly useful, but in terms of providing a well spaced grid, not in terms of stability- 1cm/s stability is not needed at the moment in the NIR Th lines are stable enough. Issue is the argon/ faint nature of the Th lines. Are there other lamps/sources we can use? Freq. Comb Steinmetz et al. 2008
The Big Issues Telluric Lines Calibration & Instrument Tracking NIR Detectors The Big Issues: Calibration Exploring Other lamps. Thorium 232 Th Uranium 238 U Heavy Element Yes Yes 0 nuclear spin Yes Yes Long ½ life Yes Yes Many Lines Yes Yes Mononucleide Yes NO (0.7% 235 U) Th/Ar Th/Ne U/Ar U/Ne In parts of the Y band that we have tested these lamps with pathfinder U seems to have significantly more lines than Th, and Ne has fewer than Ar. Further exploration of U/Ne and effect of 235U to be explored.
Other calibration systems include telecom gas cells for wavelength references, and conventional or fiber Fabry Perots to provide a grid of lines across the spectrum Mahadevan et al NIST Gas cells from Telecom. Micron optics. Temperature stabilization essential The Big Issues: Calibration
The Hobby Eberly Telescope is a 9m optical telescope in McDonald Observatory Texas Wide Field upgrade for the HETDEX will make pupil ~ 10m, significantly increase efficiency, guiding accuracy, mirror phasing etc. Post 2012 ONLY fiber fed instruments possible on the HET. HET is a non-steerable primary, can only observe objects for ~1hr around airmass 1.35 Fully queue scheduled, good for spectroscopic surveys like RV monitoring The Habitable Zone Planet Finder (HZPF) is a facility class NIR high resolution instrument that we have proposed to the NSF Major Research Instrumentation Program in August 2009 Derives its Heritage from PRVS/Gemini Study Niche Instrument-No moving parts Optimized for RVs Primary Science Goal is M dwarf planet search The HZPF on the HET
Design Concept is a White Pupil Echelle with a ZnSe Grism Cross Disperser. Primary disperser is a 200 x 800mm R4 echelle. Fast f/2 camera. Cooled but not cryogenic. No liquid nitrogen, no K band. Large beam – 150mm diameter. Spectral Resolution R > 50,000
The HZPF on the HET Coverage of Y, J and H bands. H2RG with 1.7μm cutoff LBLN Deep Depletion CCD covers Y to allow cross-comparison of velocities Upgrade path in future is a 4k x 4k H4RG-15 (when available), with CCD retired Optics designed for wide field to accommodate this path 3.5px sampling of R~50,000 resolution allows higher resolution if necessary
The HZPF on the HET Blue circle- Mike Endls ongoing M dwarf program at the HET Red circle- from Jenkins et al. 2009, late M dwarfs whose vsini is being meaured with HET to build a suitable target list for the HZPF
The HZPF on the HET SubsystemComponentEfficiency TelescopePrimary and SAC0.750 Fibre Feed1.2 seeing0.650 Fiber 30m Double Scrambler0.700 SlitSlit Losses SpectrographOrder Blocking Filter0.850 Collimator X 3, Echelle0.700 Spectrum mirror0.990 ZnSe Grism Camera Optics0.900 DetectorDetector QE (J)0.880 Total 4.8% R>50,000 Efficiency model of the HZPF Instrument in J band Will be used to survey ~300 stars at ~1-3m/s, acquiring radial velocity points on each stars, and more on anything that looks interesting Will likely be a bright time complement to the HET Dark Energy Survey (HETDEX) Possibility of sharing the focal plane with HETDEX being explored. HZPF is a fiber fed NIR spectrograph that we think can meet the recommendation of the ExoPTF within the cost cap of the NSF MRI-R 2 proposal. Tradeoffs in Resolution/Efficiency still ongoing. HET is a big fast telescope, making the instrument beam size large as well. Acknowledge significant heritage, discussion with PRVS & UPF teams!
The Big Issues Telluric Lines Calibration & Instrument Tracking NIR Detectors The NIR Precision RV spectrographs CRIRES with a gas cell on 8m VLT T-EDI on 5m Palomar PRVS, originally proposed for Gemini, not funded HZPF on the HET UPF (UKIRT Planet Finder), for UKIRT CARMENES for Calar Alto NAHUAL for the 10m GTC HDU/IRCS for Subaru (Si Immersion Grating) WINERED for Subaru ? (ZnSe Immersion Grating) SIMPLE for EELT FIRST for Apache Point Observatory 3.5 m (Si Immersion Grating) Combination of gas cell/simultaneous fiber calibration approaches. Wavelength coverage typically subset of μm. In various states of proposal/funding, and anticipated times of first light range from
The Big Issues Telluric Lines Calibration & Instrument Tracking NIR Detectors Summary NIR RVs are now < 10m/s from prototypes/initial feasibility tests results, multiple groups attempting to develop cross-dispersed high-resolution NIR spectrographs Very important for discovering the low-mass planet population around mid- late M stars, confirming astrometric detection expected in next few years, and confirming candidates from dedicated ground/space based surveys looking at low mass stars. Even if transits detected, RVs provide confirmation and mass estimates. Important to have the radius AND mass when attempting to characterize the atmosphere of potential terrestrial planets. Synergy with existing optical precision RV to help disentangle stellar activity from planetary signals. Pathfinder setup to explore issues and possible solutions to <3m/s in the NIR, which will feed into development of the HZPF on the HET