Exoplanet research at the
Thüringer Landessternwarte Tautenburg
News: Heavy Metal Planet Discovered
More information about the discovery can be found in the
ESO Science BLOG, and in the
Press releases of the Thüringer Landessternware Tautenburg
Team members: Artie Hatzes,
Eike W. Guenther, Silvia Sabotta, David Wöckel, Michael
Hartmann, Michaela Döllinger
Although the detection of extrasolar planets was impossible until the
end of the 20th century, the idea that such objects exist was
discussed since the dawn of modern astronomy. For example, the book
'Entretiens sur la pluralite des mondes' (Dialogue about the
plurality of the worlds) written by Bernhard le Bovier de Fontenelle
in 1686 became very popular. Also, Isaac Newton (1643-1727) and
Immanuel Kant (1724-1804) discussed the idea of extrasolar planets.
Since the discovery of the first extrasolar planets at the end of the
20th century there has been a tremendous increase in both
observational discoveries and theoretical work in this field of
research. Although many of the extrasolar planets found up to now are
gas-giants, the number of planets with masses below 10 MEarth is
growing rapidly. Particularly exciting was in 2009 the discovery of
CoRoT-7b the first rocky exoplanet outside the solar-system.
The Thüringer Landessternwarte Tautenburg is engaged in two large
surveys that are particularly focusing on the detection of low-mass
planets, and new planets are routinely found. Particularly interesting
are the transiting ones, for which mass and radius can be
determined. The determination of the mass and radius is currently the
best way to find out what the composition of these planets are. Do
rocky planets have an Earth-like composition, or are they very
different. Thanks to the new discoveries and new instruments, it also
now becomes possible to study the atmospheres of planets, certainly an
exciting field of research.
The space telescopes
(operating from December 27, 2006 to November 2, 2012)
(operating since March 7, 2009)
with their very high photometric precision revolutionized
our knowledge of exoplanets. We are now looking forward to the
CHEOPS (launch 2018),
TESS (launch 2018),
JWST (launch 2018).
The golden era of exoplanet research will come with the
PLATO in 2024/2026.
CARMENES (Calar Alto
high-Resolution search for M dwarfs with Exo-earths with Near-infrared
and optical Echelle Spectrographs) is a new instrument for the 3.5m
telescope at the Calar Alto Observatory, that was built by a
consortium of eleven Spanish and German institutions including the
Thüringer Landessternwarte Tautenburg.
The CARMENES instrument consists of two separate echelle spectrographs
covering the wavelength range from 550nm to 1700nm at a spectral
resolution of R = 82,000. This instrument is fed by fibers from the
Cassegrain focus of the telescope. Both spectrographs are housed in
temperature-stabilized vacuum tanks, to enable a long-term 1 m/s
radial velocity precision employing a simultaneous calibration with
two Fabry-Perots that are calibrated with ThAr, Th-Ne and U-Ne
emission line lamps. The contribution of the Thüringer
Landessternwarte Tautenburg to the project was building the two
calibration units. CARMENES has been optimized for a search for
terrestrial planets in the habitable zones (HZs) of low-mass stars,
which may well provide our first chance to study environments capable
of supporting the development of life outside the Solar System. With
its unique combination of optical and near-infrared echelle
spectrographs, CARMENES will provide better sensitivity for the
detection of low-mass planets than any comparable instrument, and a
powerful tool for discriminating between genuine planet detections and
false positives caused by stellar activity. The CARMENES survey of 300
M dwarfs has started in January 2017.
CARMENES has now made its first discoveries.
New planet was found
in the GJ1148-system and it was found that the claimed planet
of GJ15A with a period of 11.4 days does not exist. See
for more details. Previously discovered planets
in GJ176, GJ436, GJ536, GJ1148, GJ581 and GJ876 were confirmed.
See also this
press release, and
Transiting exoplanets are benchmark objects. Like an eclipsing binary
star, a transiting exoplanet offers unique opportunities for a rich
variety of follow-up studies due to its favourable orbital
geometry. It is possible to measure a planet's fundamental bulk
properties like mass and radius, study its atmosphere photometrically
or spectroscopically, and measure the alignment between the planet's
orbit and the host star's spin axis. More so than eclipsing binary
stars, transiting exoplanets are difficult to detect. Wide-field
ground-based transit surveys have detected hundreds of hot Jupiters,
but the sensitivity of these surveys falls off quickly at longer
orbital periods and smaller planet radii. Space telescopes like
Kepler with their very high photometric precision revolutionized
our knowledge of exoplanets. The survey with the Kepler telescope is
now extended K2 mission.
The KESPRINT team is analysing the light-curves, and carrying follow-up
observations with ground-based telescopes in order to determine the
stellar parameters and to measure the masses of the planets. The
KESPRINT teams has made already many discoveries, a particularly
exciting one was the discovery of the planets of
HD3167. HD3167 is a bright (V=8.9 mag) K0V star. HD3167b, an
ultra-short-period (0.96 days) super-Earth, and HD3167c, a
mini-Neptune on a relatively long-period orbit (29.85 days). With a
mass of 5.7 MEarth, a radius of 1.6 REarth, and a mean density of 8
gcm-3, HD3167b joins the small group of ultra-short-period planets
known to have rocky terrestrial compositions. This planet thus
resembles CoRoT-7b but the star is much brighter, allowing very
detailed studies. HD3167c has a mass of 8 MEarth and a radius of 2.7
REarth, yielding a mean density of 2.2 gcm-3, indicative of a planet
with a composition comprising a solid core surrounded by a thick
atmospheric envelope. The rather large pressure scale height (350 km)
and the brightness of the host star makes HD3167c an ideal target for
atmospheric characterization via transmission spectroscopy across a
broad range of wavelengths.
Our main work-horses are the FIES, HARPS, HAPS-N and the CARMENES
spectrographs. FIES is at the 2.6m Nordic Optical Telescope (NOT),
HARPS-N at the 3.5m Telescopio Nazionale "Galileo" (TNG), both
telescopes are at the Observatorio del Roque de los Muchachos. HARPS
at the 3.6m telescope at La Silla, and CARMENES at the 3.5m telescope
at Calar Alto.
Dome of the NOT at the Observatorio del Roque de los Muchachos.
That is where FIES is.
Dome of the TNG at the Observatorio del Roque de los Muchachos.
That is where HARPS-N is.
Dome of the 3.6m telescope at La Silla.
That is where HARPS is.
Dome of the 3.5m telescope at Calar Alto observatory.
That is where CARMENES is.
Seeing monitor at Calar Alto observatory.
The Thüringer Landessternwarte Tautenburg is involved in
upgrading the near-infrared spectrograph CRIRES on the VLT
CRIRES+. The upgrade project CRIRES+, transforms this VLT
instrument into a cross-dispersed spectrograph to increase the
wavelength range that is covered simultaneously by a factor of ten. In
addition, a new detector focal plane array of three Hawaii 2RG
detectors with a 5.3 mum cut-off wavelength will replace the existing
detectors, a new spectroparimetric unit will be added and the
calibration system will be enhanced.
This instrument will have great potentials for the studies of planets
orbiting cool stars and studies of the atmospheres of planets.