J. A. Caballero's Humboldt-Foundation
Research Stay in Germany
Renewed
"Blaue Erden bei roten Zwergen" – Heidelberg, Göttingen,
Hamburg, Tautenburg
CARMENES (Calar Alto high-Resolution search for M dwarfs with
Exoearths with Near-infrared and optical Échelle Spectrographs,
http://carmenes.caha.es/) is a next-generation instrument being built
for the Zeiss 3.5 m telescope at the Calar Alto Observatory
(Andalusia, Spain) by a consortium of German and Spanish
institutions. In plain English, it is a complex machine to look for
planets like our Earth around close, small, red stars, dubbed M
dwarfs.
In detail, CARMENES consists of two separated spectrographs
covering the wavelength ranges from 0.5 to 1.0 µm and from 1.0 to
1.7 µm with spectral resolutions R = 82,000, each of which shall
perform high-accuracy radial-velocity measurements (∼1 m s-1) with
long-term stability. The fundamental science objective of CARMENES
is to carry out a radial-velocity survey of ∼300 late-type mainsequence stars with the goal of detecting low-mass planets in their
habitable zones. We aim at being able to detect 2 MEarth planets in
the habitable zone of M5V stars. Habitable planets have liquid water
on their surfaces and are expected to be blue, which explains the title
of this research project: “Blue earths near red dwarfs”. The
CARMENES first light is expected to occur in Summer 2015.
The consortium that builds CARMENES is made of the Max-PlanckInstitut
für
Astronomie
Heidelberg,
Landessternwarte
Königstuhl Heidelberg, Institut für Astrophysik Göttingen,
Thüringer Landessternwarte Tautenburg and Hamburger
Sternwarte, together with the Observatory of Calar Alto and five
research institutions and universities in Spain. In total, we are about
130 researchers and engineers in Germany and Spain.
Dr. Caballero is the CARMENES deputy project manager,
communication manager, webmaster, leader of the data work
package, and responsible of numerous managerial, engineering, and
scientific tasks. Only a few months ahead of the first tests at the
Observatory, and less than a year ahead of the start of the survey, it
becomes critical to define the list of M dwarfs that CARMENES will
observe. One of the main Dr. Caballero’s scientific tasks is to
coordinate the preparation of the CARMENES input catalogue,
which is a comprehensive, exhaustive compilation of M dwarfs and
stellar data from which the CARMENES science team will carefully
choose the best, brightest, latest, slowest-rotator, single, M-dwarf
targets. An incorrect star choice translates into lower probabilities of
discovering new exoearths.
CARMENCITA, the CARMENES Cool star Information and daTa
Archive, is that M-dwarf database from where we will choose our best
target sample. CARMENCITA currently catalogues over 2200 M dwarfs
visible from the Calar Alto Observatory. For each star, we tabulate
dozens of parameters compiled from the literature or measured by us
with new data, such as: accurate astrometry, spectral typing,
photometry in 20 bands from the ultraviolet to the mid-infrared,
rotational and radial velocities, X-ray count rates and hardness ratios,
close and wide multiplicity data, basic stellar parameters derived from
sythetic model fits, etc. It is being continuously updated with the
most precise parameters. The private on-line catalogue, including
preparatory science observations (i.e., high-resolution imaging, lowand high-resolution spectroscopy), will be eventually public as a
CARMENES legacy and will represent a worldwide cornerstone in the
investigation of cool stars in the solar neighbourhood.
While the CARMENCITA data compilation is centralized at the Dr.
Caballero’s location in Madrid, key parts of the analysis are also
distributed among the other institutions involved in CARMENES, both
in Spain and Germany. The aim of this proposal for a HumboldtFoundation Renewed Research Stay in Germany is to allow Dr.
Caballero to complete the best CARMENES input catalogue in
close collaboration with colleagues at the five German
centres:
• Institut für Astrophysik Göttingen (host: Prof. A. Reiners).
Maximum priority will be given to the analysis, interpretation
and publication of the preparatory high-resolution spectra
obtained with telescopes in Chile, Spain and USA, and the study
of stellar activity.
• Landessternwarte Königstuhl Heidelberg (host: Prof. A.
Quirrenbach). Work will be focused on the CARMENCITA visual
interface of the “golden sample”, i.e. the stars that today have
the highest chances to be observed.
• Hamburger Sternwarte (host: Prof. J. H. M. M. Schmidt).
Efforts will be devoted to create the largest compendium of M
dwarfs with X-ray emission from ROSAT data, which will be in
turn an excellent input catalogue for eROSITA.
• Max-Planck-Institut für Astronomie (host: Prof. R. Mundt).
We will draw a plan on how to maximize the synergies between
the Planet and Star Formation group at MPIA and the
CARMENES consortium for the science exploitation phase.
• Thüeringer Landessternwarte Tautenburg (host: Dr. E. W.
Guenther). We will investigate how the tools and instruments
used successfully in radial-velocity monitoring by the TLS team
can be implemented in parallel to the CARMENES survey.
This is a step-by-step process that cannot be accomplished in a single
stay, but in five dedicated stays approximately in the same order
as listed. For preparing the next step, a gap between two consecutive
stays of about one month is needed. Because of Dr. Caballero’s
commitmments (CARMENES deputy project manager, supervisor of
PhD students and lecturer of master courses in Madrid, member in
international boards), each stay will be one week long (from
Monday morning to Friday afternoon). Such relatively short stays
have the benefit of maximizing efficiency and minimizing travel
expenses, but force to have a well pre-defined stay schedule.
In the case of the stay at the Institut für Astrophysik Göttingen
with Prof. A. Reiners, Prof. S. Dreizler, Dr. S. V. Jeffers, Dr. U.
Lemke, Dr. M. Zechmeister, F. Bauer, A. Lamert, C. Marvin, V.-M.
Passegger, L.-F. Sarmiento and S. Schäfer, the main Dr. Caballero’s
tasks will be to check:
• Status of the reduction and preliminary analysis of all the
FEROS, CAFÉ and HRS spectra (he coordinated the
observations in Chile and Spain).
• Target coordinates and names and to help preparing a log-table
of observations.
• Derived spectral types, and to compare with previous
measurements and look for outliers.
• Derived rotational velocities, and to compare with previous
measurements, help plotting them versus rotation periods and
activity indicators (Hα pseudo-equivalent width, X-ray flux) and
help defining a spectral type-dependent vsini upper limit for
CARMENES selection.
• Derived effective temperatures, surface gravities and
metallicities, and to compare with spectral indices sensitive to
those parameters (e.g., TiO5 bands, Na doublet, zeta index),
look for outliers and help with interpretation.
• Single-epoch and multi-epoch radial velocities and draw a plan
on how to use them for making a comprehensive kinematics
analysis.
• Derived Hα pseudo-equivalent widths, and to study the
accretion-chromosphere emission boundary and Hα variability
in multi-epoch observations.
• In-preparation manuscripts for the Astronomy & Astrophysics
journal on the analysis of the high-resolution spectra, or to edit
or help editing them.
• Status of the automatic data pipeline development (a piece of
software needed since the CARMENES first light).
• Status of the NIR+VIS Fabry-Pérot etalon (a piece of hardware
needed for an accurate wavelength calibration of the
CARMENES spectra).
Dr. Caballero will be working with F. Bauer, A. Lamert, C. Marvin,
V.-M. Passegger, L.-F. Sarmiento and S. Schäfer to provide them with
information that they will need for their PhD theses.