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Project NIRRVS: Precise Near-Infrared Radial Velocities

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Peter Plavchan

on 15 June 2015

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Transcript of Project NIRRVS: Precise Near-Infrared Radial Velocities

Project NIRRVS: Precise Near-Infrared Radial Velocities
Peter Plavchan
Assistant Professor
Missouri State University
70% of main sequence stars are M dwarfs

M dwarfs span a factor of 5 in Mass/Radius, ~103 in Luminosity
All of AFGK stars span a factor of ~2.5 in Radius, ~5 in mass, ~300 in Luminosity

The M Dwarf Opportunity

Leger et al. 2009

Charbonneau et al. 2010

The M Dwarf Opportunity

GJ 1214

55 Cnc

The M Dwarf Opportunity
~ Visible RV limit

The M Dwarf Opportunity

Howard et al. 2012

The smallest planets in the Kepler
sample are predominantly found
around low-mass stars

Stellar Mass
The NEW M Dwarf Opportunity

α Cen B

Dumusque et al., 2012

The small planetary RV signal is comparable to numerous periodic perturbing stellar jitter signals - spot modulation & magnetic activity cycles
Spoiling the M Dwarf Opportunity

-> Observe in the near-infrared, where M dwarfs put out much of their bolometric luminosity

M dwarfs are red, V-K > ~3.5
Only 4 >M4 with V<12
Spoiling the M Dwarf Opportunity

Planet signal

ΔTspot = 200 K
Reiners et al. 2009

2800 K

3700 K

5700 K

Bonus: Stellar Activity is Wavelength Dependent

NIR Spectroscopy -> NIR PRVs

~14” or ~35 cm

We are using CSHELL on IRTF as a testbed for several NIR RV techniques, adapted from the visible

Project NIRRVS

This work is part of a long-term plan to upgrade NIRSPEC on Keck II (R~50k, 250 nm), and to enable PRVs on iSHELL on IRTF (2016; R~70k, 250 nm)

Project NIRRVS









Why has methane been missed?
Telluric methane!
By using an isotopologue or deuterated methane, the reduced mass changes.
The ro-vibrational lines shift by ~10 nm!

Choice of gas: METHANE

Gas cell assembled and integrated at IRTF


The IRTF on Mauna Kea

Pilot data (2010 - 2012) 1,400 spectra for 14 targets of young moving group M dwarfs

We obtained 56 IRTF nights in 2014.
Targeted bright nearby M dwarfs not previously surveyed by HARPS / CPS visible planet search teams

1,000+ spectra for 22 targets

For 2014 data we get S/N ~ 200 per night per target

AT Mic A - 39 m/s
12 Myr rapidly rotating M dwarf

GJ 15A: rms = 27 m/s
M2V “stable” star

Howard et al. 2014

Our data: from MSU student Nick Ogden:
Upper limit of 51 m/s: <93 MEarth

A planet around GJ 15A?

GJ 876 - An M dwarf with two resonant Jovian planets

P = 2.2 days
Msini < Saturn mass
FAP ~ 10%

A possible planet?

Another possible planet?

We have carried out a survey of 14 young low mass stars @ ~30-60 m/s photon noise, and 22 M dwarfs @ ~20-30 m/s photon noise

We are in the process of writing 3 papers!

Five years of effort has gone into our pipeline

Comparing young and nearby M dwarfs sample results in progress…

Two planet candidates rejected by follow-up observations

Proposals submitted for fall to observe our best candidates

Project NIRRVs Summary

Looking towards the future, we have made the gas cells for iSHELL, which will replace CSHELL in 2016, and we hope to get to < 5 m/s precision with iSHELL due to the increased spectral grasp alone.

The increased efficiency, resolution, no fringing, and smaller number of bad pixels will provide further improvements.

We have also delivered the gas cells for NIRSPEC on the Keck telescope, for which a MRI upgrade proposal is pending.


Transits are deeper
Habitable Zones are closer
RV amplitudes are larger
Candidate/Known RV variables
Full transcript