An Error Budget for Precise Radial Velocities from Keck-HIRES - - PowerPoint PPT Presentation

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An Error Budget for Precise Radial Velocities from Keck-HIRES - - PowerPoint PPT Presentation

Jun 16, 2023 133 likes •1.08k views

An Error Budget for Precise Radial Velocities from Keck-HIRES Andrew W . Howard Townes Fellow, UC Berkeley California Planet Search Team: Geoff Marcy, Debra Fischer, John Johnson, Jason Wright, Howard Isaacson, Julien Spronck, Jeff Valenti,

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SLIDE 1

An Error Budget for Precise Radial Velocities from Keck-HIRES

Andrew W . Howard Townes Fellow, UC Berkeley

California Planet Search Team: Geoff Marcy, Debra Fischer, John Johnson, Jason Wright, Howard Isaacson, Julien Spronck, Jeff Valenti, Jay Anderson, Nikolai Piskunov, more!

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SLIDE 2

ASTRO2010

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SLIDE 3

ASTRO2010

Three primary science objectives for the next decade:

  • 1. Search for the first stars, galaxies,

and black holes

  • 2. Seek nearby habitable planets.
  • 3. Advance our understandings of the

fundamental physics of the universe.

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SLIDE 4

ASTRO2010

“This survey is recommending a program to explore the diversity and properties of planetary systems around other stars, and to prepare for the long-term goal of discovering and investigating nearby, habitable planets.” - page 7-7 “Using existing large ground-based or new dedicated mid-size ground-based telescopes equipped with a new generation of high- resolution spectrometers in the optical and near-infrared, a velocity goal of 10 to 20 centimeters per second is realistic.” - page 7-8

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ASTRO2010

“This survey is recommending a program to explore the diversity and properties of planetary systems around other stars, and to prepare for the long-term goal of discovering and investigating nearby, habitable planets.” - page 7-7 “Using existing large ground-based or new dedicated mid-size ground-based telescopes equipped with a new generation of high- resolution spectrometers in the optical and near-infrared, a velocity goal of 10 to 20 centimeters per second is realistic.” - page 7-8

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ASTRO2010

“This survey is recommending a program to explore the diversity and properties of planetary systems around other stars, and to prepare for the long-term goal of discovering and investigating nearby, habitable planets.” - page 7-7 “Using existing large ground-based or new dedicated mid-size ground-based telescopes equipped with a new generation of high- resolution spectrometers in the optical and near-infrared, a velocity goal of 10 to 20 centimeters per second is realistic.” - page 7-8

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SLIDE 7

ASTRO2010

To prepare for direct imaging, “NASA and NSF should support an aggressive program of ground-based high-precision radial velocity surveys

  • f nearby stars to identify potential candidates” - page 1-8
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SLIDE 8

ASTRO2010

Top Ground-based Recommendations (Large Projects):

  • 1. LSST
  • 2. Mid-scale Innovations Projects - including

“Develop RV surveys and spectrometers to determine the properties of extrasolar planets”

  • 3. Giant Segmented Mirror Telescope (TMT or GMT)
  • 4. ACTA (Cerenkov Telescope)
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SLIDE 9

ASTRO2010

SIM-Lite could characterize 50 nearby planetary systems down to an Earth-mass Rejected for 3 reasons:

  • 1. Large cost ($1.9B)
  • 2. Time to launch (8.5 yr)
  • 3. Target-finding for direct missions can

be done partially by RV with "challenging but achievable precision below 10 cm/s" SIM-Lite

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SLIDE 10

ASTRO2010

PRV Workshop Describe instrumental diffjculties

↓

Value

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Keck/HIRES

Keck 1 Telescope Iodine Cell

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SLIDE 12

HIRES

!

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SLIDE 13

HIRES

!

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SLIDE 14

HIRES

!

I2

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SLIDE 15

HIRES

!

I2 Slit

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SLIDE 16

HIRES

!

Guider I2 Slit

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HIRES

!

Guider Collimator I2 Slit

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SLIDE 18

HIRES

!

Guider Collimator E c h e l l e G r a t i n g I2 Slit

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SLIDE 19

HIRES

!

Guider Collimator E c h e l l e G r a t i n g Cross-disperser I2 Slit

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HIRES

!

Guider Collimator E c h e l l e G r a t i n g Cross-disperser I2

{

Camera Slit

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HIRES

!

Guider Collimator E c h e l l e G r a t i n g Cross-disperser CCD Dewar I2

{

Camera Slit

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Echelle Spectrum

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Iobs(") = k[TI 2(")# IS(" + $")] %PSF

RVs with Iodine

Dop

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Pushing down to K < 2 m/s

Star: HD 156668 (K3V) distance = 24 pc V = 8.3 [Fe/H] = 0.05 quiet Planet: M sin i = 4.15 ME P = 4.6455 d e = 0 (fixed)

Howard et al. 2010, ApJ (submitted), arXiv 1003:3444

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Pushing down to K < 2 m/s

Star: HD 156668 (K3V) distance = 24 pc V = 8.3 [Fe/H] = 0.05 quiet Planet: M sin i = 4.15 ME P = 4.6455 d e = 0 (fixed)

Howard et al. 2010, ApJ (submitted), arXiv 1003:3444

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SLIDE 26

Pushing down to K < 2 m/s

Star: HD 156668 (K3V) distance = 24 pc V = 8.3 [Fe/H] = 0.05 quiet Planet: M sin i = 4.15 ME P = 4.6455 d e = 0 (fixed)

Howard et al. 2010, ApJ (submitted), arXiv 1003:3444

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SLIDE 27

HIRES and HARPS

HD 156668 b (HIRES) GJ 581 e (HARPS)

RMS = 1.53 m/s K = 1.85 m/s

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SLIDE 28

HIRES and HARPS

HD 156668 b (HIRES) GJ 581 e (HARPS)

RMS = 1.53 m/s K = 1.85 m/s

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SLIDE 29

HIRES and HARPS

HD 156668 b (HIRES) GJ 581 e (HARPS)

RMS = 1.53 m/s K = 1.85 m/s

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SLIDE 30

Standard Stars

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SLIDE 31

Standard Stars

The best standards have an RMS of 1.5-2.0 m/s.

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Standard Stars

The best standards have an RMS of 1.5-2.0 m/s. These are almost always late G / early K dwarfs.

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SLIDE 33

Standard Stars

The best standards have an RMS of 1.5-2.0 m/s. These are almost always late G / early K dwarfs. We do not explicitly average

  • ver P-modes; Texp ~ 1-5 min
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SLIDE 34

!

Standard Stars

!

HD 10700 (Tau Ceti)

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Standard Stars

!

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Standard Stars

!

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SLIDE 37

Standard Stars

!

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Standard Stars

!

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SLIDE 39

2 4 6 8 10 Velocity RMS (m/s) 10 20 30 40 Number of Stars

HIRES Velocity RMS

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SLIDE 40

Velocity RMS

HIRES HARPS

2 4 6 8 10 Velocity RMS (m/s) 10 20 30 40 Number of Stars

Mayor and Udry, 2008,

  • Phys. Scr. T130, 014010

GK stars in Eta-Earth Survey Known planets removed

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SLIDE 41

Velocity RMS

HIRES HARPS

2 4 6 8 10 Velocity RMS (m/s) 10 20 30 40 Number of Stars

Mayor and Udry, 2008,

  • Phys. Scr. T130, 014010

2-3.5 m/s 1-3 m/s

GK stars in Eta-Earth Survey Known planets removed

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SLIDE 42

Challenge: Stability and Precision at 0.3-0.5 m/s

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Sources of RV Errors

Instrumental

(and modeling)

Astrophysical Poisson

(0.5-1.0 m/s)

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SLIDE 44

Sources of RV Errors

Instrumental

(and modeling)

Astrophysical Poisson

(0.5-1.0 m/s)

Not Limiting

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SLIDE 45

Sources of RV Errors

Instrumental

(and modeling)

Astrophysical Poisson

(0.5-1.0 m/s)

Not Limiting see talks today

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SLIDE 46

Sources of RV Errors

Instrumental

(and modeling)

Astrophysical Poisson

(0.5-1.0 m/s)

Not Limiting see talks today This Talk see also talks by Valenti, Spronck

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SLIDE 47

HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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Intentional Mis-guiding

Guide Middle Guide Low Guide High Extreme mis-guiding -> 4 m/s

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!

Intentional Mis-guiding - PSF Asymmetry

PSF shape changes with mis-guiding

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Intentional Mis-guiding - PSF Asymmetry

PSF shape changes with mis-guiding

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! ! ! ! ! ! ! ! !

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!

Normal Guiding - PSF Variations

Jay Anderson, STSCI

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Normal Guiding - PSF Variations

Jay Anderson, STSCI

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!

Normal Guiding - PSF Variations

Jay Anderson, STSCI

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Normal Guiding - PSF Variations

Jay Anderson, STSCI

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!

Normal Guiding - PSF Variations

Jay Anderson, STSCI

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!

Normal Guiding - PSF Variations

Jay Anderson, STSCI

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HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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!

Hartmann Mask Tests

Hartmann Mask

!

Standard Collimator Mask

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!

Vignetting

Dewar shadow

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!

HIRES Vignetting

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!

ThAr Spectra

No Hole With Hole

R ~ 150,000 R = 60,000

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!

Iodine Spectra

R ~ 150,000 R = 60,000 No Hole With Hole

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!

Vignetting & Pupil Illumination

Intentional mis-guiding along spatial direction → varying continuum

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HIRES RV Errors Summary So Far:

HIRES PSF will vary due to two effects:

  • 1. The non-uniformly imaged slit that is

imaged on the CCD

  • 2. The non-uniform pupil illumination of the

imperfect HIRES optics by the knife-edge effect on the pupil when the telescope is not in perfect focus.

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SLIDE 67

HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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SLIDE 68

Lick Test Fiber

Julien Spronck - Yale

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Lick Test Fiber

Julien Spronck - Yale

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Breadboard

Lick Test Fiber

Julien Spronck - Yale

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Fiber Slit Mean Pixel Shift Guiding (-1: left, 0: center, +1: right)

  • 2
  • 1

1 2 0.6 0.4 0.2 0.0

  • 0.2
  • 0.4
  • 0.6

Fiber Input - Lick Mis-guiding Tests

PSF Stability: ~1.0 pixel → <0.01 pixels

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SLIDE 72

Image of Fiber output

Lick Test Fiber

Julien Spronck - Yale

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SLIDE 73

Keck Fiber Scrambler

Julien Spronck - Yale

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Keck Fiber Scrambler

Julien Spronck - Yale

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SLIDE 75

See Julien Spronck’ s Talk

  • n Wednesday

“Fiber Scrambling at Lick and Keck Observatory”

Julien Spronck

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HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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A-band (O2) at 760 nm

Scattered Light < 70/4e4 = 0.002 Intrinsically Black? Probably No.

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A-band (O2) at 760 nm

Scattered Light < 70/4e4 = 0.002 Intrinsically Black? Probably No.

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Scattered Light - Laser Tests

Laser Exposures by Grant Hill (Keck Observatory) Stacked Image by Jeff Valenti (STScI)

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SLIDE 80

Scattered Light - Laser Tests

Laser Exposures by Grant Hill (Keck Observatory) Stacked Image by Jeff Valenti (STScI)

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Entire Laser Profile on Log Scale

1.3% of LSF is

  • utside ±7 pixels

6328.16 Å 5939.32 Å 5433.65 Å Red Laser Yellow Laser 5433.65 Å

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SLIDE 82

Entire Laser Profile on Log Scale

6328.16 Å 5939.32 Å 5433.65 Å Red Laser Yellow Laser Blue Laser

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SLIDE 83

Entire Laser Profile on Log Scale

10X Error Convolved Iodine Iodine 10X LSF LSF

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HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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Sky Contamination - Faint Stars

Kepler-8, V=13.9 mag (45 min, full moon) 4 Echelle orders: Moonlight, Sky lines, Cosmic rays

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Sky Contamination - Faint Stars

Kepler-8, V=13.9 mag (45 min, full moon) 4 Echelle orders: Moonlight, Sky lines, Cosmic rays

Column cut

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Sky Contamination - Faint Stars

Full Moon, Clear skies: Sky is ~3% of 14th mag star (3 arcsec long slit)

0.8” seeing

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Sky Contamination - Faint Stars

Full Moon, Clear skies: Sky is ~3% of 14th mag star (3 arcsec long slit)

0.8” seeing

Stellar Orders

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Sky Contamination - Faint Stars

Full Moon, Clear skies: Sky is ~3% of 14th mag star (3 arcsec long slit)

0.8” seeing

Sky Stellar Orders

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Sky Contamination - Faint Stars

Full Moon, Clear skies: Sky is ~3% of 14th mag star (3 arcsec long slit)

0.8” seeing

Sky Stellar Orders

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Sky subtraction

Sky Sky Star

Cosmic ray

Subtract median sky value from each pixel in extraction region Essential for V ≥ 10 for 1 m/s

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Summary: HIRES RV Errors

Guiding Zonal aberrations / vignetting Fibers (The Solution!) Scattered light - HIRES Sky subtraction for faint targets

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Questions?