What is NAHUAL?
Description
NAHUAL (Near-infrAred High-resolUtion spectrogrAph for pLanet hunting)
is a project intended to develop a near-infrared high-resolution echelle
spectrograph for a 10-m class telescope.
The main scientific objective of the instrument is to measure the radial
velocity (RV) with very high precision (goal of 1 m/s) in the near infrared.
This will facilitate the detection of exoplanets of low mass (possibly of rocky
type) around cool stars and brown dwarfs with spectral types K, M and L (M-type
stars are the most numerous in the solar vicinity and in the Milky Way).
This can be achieved because of two fundamental reasons:
- Up to now, exoplanets have mostly been detected around nearby
Sun-like stars with the wobble radial velocity (RV) method using optical
spectrographs. In the infrared, the signal-to-noise ratio (SNR) is
increased with respect to the optical for spectral types K, M and L, and
hence it is expected to improve the precision in RV measurement roughly
linearly with the gain in SNR. When the stellar mass diminishes, the RV
amplitude increases for the wobble due to an exoplanet. Therefore, for a
given precision in the measurent it is possible to detect exoplanets of
smaller mass in the infrared that in the optical.
- In the infrared, the contrast between the photosphere and the
magnetic spots that are the cause of the noise in the measurements of RV
diminishes.
The spots produce asymmetries in the profiles of the spectral lines.
Therefore, we expect to increase the sensitivity in the exoplanet
detection in young low-mass stars and brown dwarfs using NAHUAL.
NAHUAL will also offer to the community a new facility for a great variety of
scientific programs, as for example: detailed studies of the atmospheres and
cool stars, chemical composition, studies of stellar activity (particularly by
means of measurements of magnetic field using the Zeeman effect),
characterization of protoplanetary discs, asteroseismology, and characterisation
of gamma-ray bursts.
Motivation
NAHUAL is mainly thought to measure RV variations in M dwarfs with the goal of
detecting life-bearing rocky planets around them.
This is a new niche of Modern Astrophysics that requires an instrument with the
unique capabilities of NAHUAL that, in general, will allow the science community
to perform:
- Radial velocity searches for planets around ultracool dwarfs
- Radial velocity searches for planets around young red stars
- Dynamical studies of protoplanetary discs
- Dynamical studies of pre-planetary nebulae stars
- Chemical composition of Solar System bodies
- Magnetic fields in red objects
- Asteroseismology of red stars
- Gamma ray burst afterglow spectroscopic studies
Nahualli, Nagual and Tezcatlipoca
A Nahual or Nagual (both pronounced /na-wál/) is, among
Mesoamerican indigenous, a human being or a god who has the power to magically
adopt animal forms.
For example, Tezcatlipoca's nahual was the jaguar (Panthera onca, the
third-largest feline after the tiger and the lion).
Tezcatlipoca, "Lord of the Near and the Night" and "Possessor of the Sky and the
Earth", was a central deity in Aztec religion together with Quetzalcoatl.
The word Nahual comes from the Nahuatl word nawalli, which was
interpreted by the Spanish invaders and their priesthood as "practitioner of
harmful magic".
In modern rural Mexico, Nahuals are thought to shapeshift into animals at night
and hunt innocent victims.
Instead of it, our NAHUAL will hunt
exoplanets at night!
