ripl radio interferometric planet search
Download
Skip this Video
Download Presentation
RIPL Radio Interferometric Planet Search

Loading in 2 Seconds...

play fullscreen
1 / 29

RIPL Radio Interferometric Planet Search - PowerPoint PPT Presentation


  • 257 Views
  • Uploaded on

RIPL Radio Interferometric Planet Search. Geoffrey Bower UC Berkeley. Collaborators: Alberto Bolatto (UMD), Eric Ford (UFL), Paul Kalas, Anna Treaster, Vince Viscomi (UCB). MM Wavelength T Tauri Outburst in Orion. 2 nd most luminous stellar radio outburst

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'RIPL Radio Interferometric Planet Search' - Rita


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
ripl radio interferometric planet search

RIPLRadio Interferometric Planet Search

Geoffrey Bower

UC Berkeley

Collaborators: Alberto Bolatto (UMD), Eric Ford (UFL),

Paul Kalas, Anna Treaster, Vince Viscomi (UCB)

mm wavelength t tauri outburst in orion
MM Wavelength T Tauri Outburst in Orion
  • 2nd most luminous stellar radio outburst
  • Briefly, brightest object in nebula
  • Required long baselines for detection
  • Magnetized T Tauri outburst
  • Contemporaneous with X-ray outburst
  • Many such objects likely to be found by CARMA & ALMA

BIMA A configuration images

(Bower, Plambeck, Bolatto, Graham, de Pater, McCrady, Baganoff 2004)

orion nebula parallax w star gmr a
Orion Nebula Parallaxw/Star GMR-A

D=389 pc +/- 5%

<0.1 mas/epoch

Sandstrom, Peek, Bower, Bolatto,

Plambeck 2007

Astro-ph/0706.2361

requirements of a planet survey
Requirements of a Planet Survey
  • Low mass, nearby star
    • Astrometric displacement ~ 1 mas
  • Nonthermal radio emission
    • S ~ 1 mJy
    • F ~ GHz
    • Positional stability < 0.1 mas
  • Stable Image
    • Active, but not too active
vla m dwarf flux survey
VLA M dwarf Flux Survey
  • 174 X-ray selected nearby M dwarfs
  • 10 minute VLA observations with 50 microJy rms
  • 40 detections of 29 stars
  • Rough agreement X-ray-radio correlation
  • No distinction between early and late types

Bower, Bolatto, Ford, Kalas 2009, ApJ, in press

stars are variable
Stars are Variable

EV Lac

Osten et al 2005

pilot survey
Pilot Survey
  • 7 stars
  • 3 epochs
  • < 10 days
    • Hipparcos errors ~ 1 mas/y
    • Error over 10 days < 0.1 mas
  • Test
    • Detectability
    • Image stability

8000 km baselines

3 cm wavelength

1 mas resolution

Astrometry ~ beam/SNR

results from pilot study apparent motion of gj 4247
Results from Pilot Study:Apparent Motion of GJ 4247

15 mas

26 March 2006

25 March 2006

23 March 2006

Comparison of radio positions (points) with predictions from Hipparcos astrometry (solid line) reveal noise-limited rms residuals ~0.1 milliarcseconds, approximately 1 stellar diameter.

Bower, Bolatto, Ford, Kalas 2009, ApJ, in press

pilot study results
Pilot Study Results

GJ 4247

GJ 896A

Residuals are sensitivity limited

~0.2 mas

GJ 65B

results from pilot study constraints on companion masses
Results from Pilot Study:Constraints on Companion Masses

Planet Mass (Mjup)

Semi-major Axis (AU)

  • Agreement with optical astrometry sets upper limit on acceleration and therefore companion masses
    • Mp < 3 – 10 MJup @ 1 AU
  • Sensitivity is limited by the short lever arm of VLBA observations: ~10 days
  • RIPL will extend this lever arm by factor of 100

Bower, Bolatto, Ford, Kalas 2009, ApJ, in press

ripl radio interferometric planet search16
RIPLRadio Interferometric Planet Search
  • 30 stars
  • 12 epochs/4 years
  • VLBA + GBT
  • 512 Mb/s
  • 2 hours on source + 2 hours calibration
  • 25 microJy rms
    • 4 x lower than pilot survey
  • 1392 hours total

Key question: What is fraction of long-period planets around low mass stars?

ripl sample
RIPL Sample
  • 30 Stars
  • M1 – M8
  • V = 9.6 – 15.8 mag
  • S_6cm = 0.1 – 6 mJy
  • D = 2.7 – 9.5 pc
  • 11 are members of known binary or multiple systems
current status
Current Status
  • Observing began Oct 2007
    • Approximately 4 observations/month
  • Expected completion in mid-2011
  • 40% complete
  • Pipeline processing underway (see poster by Vince Viscomi)
  • All stars detected
    • 60% of stars detected in every epoch
benefits of astrometric detection
Benefits of Astrometric Detection
  • Unique method
  • Breaks degeneracy of RV searches for mass, inclination angle, and ascending node
  • Probes low mass, active stars that are difficult to study with RV method
  • Planet fraction of low mass stars poorly determined
  • Detects planets that can be studied with extreme AO
  • Ties radio and optical astrometric reference frame
future directions for radio astrometry planets
Future Directions for Radio Astrometry & Planets
  • Bandwidth upgrade for VLBA
    • 512 Mb/s  8 Gb/s
    • 4 x sensitivity
    • Calibrator density increases by 8 x
    • In-beam calibrators
    • 10 microarcsec accuracy  Neptune mass planets
  • Square Kilometer Array
    • 100 x sensitivity
    • 3000-5000 km baselines
    • 1 microarcsec accuracy  Earth mass sensitivity
summary
Summary
  • Radio astrometry is sensitive to sub-Jupiter mass planets around M dwarfs
  • We can already exclude BD companions to three stars based on only three measurements
  • RIPL survey will probe low mass, active star parameter space
ad