Publications (46)
Long-term stellar activity of M dwarfs: A combined K2 and TESS study of two early M-type stars
St. Raetz, B. Stelzer
Studies of the rotation and activity of M type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution. Using the outstanding photometric…
Flares and rotation of M dwarfs with habitable zones accessible to TESS planet detections
B. Stelzer, M. Bogner, E. Magaudda +1
We characterize the magnetic activity of M dwarfs to provide the planet community with information on the energy input from the star; in particular, in addition to the frequency of…
Refining Parameters of the XO-5 Planetary System with High-Precision Transit Photometry
G. Maciejewski, M. Seeliger, Ch. Adam +2
Studies of transiting extrasolar planets offer an unique opportunity to get to know the internal structure of those worlds. The transiting exoplanet XO-5 b was found to have an ano…
Constraints on a second planet in the WASP-3 system
G. Maciejewski, A. Niedzielski, A. Wolszczan +30
There have been previous hints that the transiting planet WASP-3 b is accompanied by a second planet in a nearby orbit, based on small deviations from strict periodicity of the obs…
Long-Term Photometry of IC 348 with the YETI Network
D. J. Fritzewski, M. Kitze, M. Mugrauer +29
We present long-term photometric observations of the young open cluster IC 348 with a baseline time-scale of 2.4 yr. Our study was conducted with several telescopes from the Young…
YETI observations of the young transiting planet candidate CVSO 30 b
St. Raetz, T. O. B. Schmidt, S. Czesla +32
CVSO 30 is a unique young low-mass system, because, for the first time, a close-in transiting and a wide directly imaged planet candidates are found around a common host star. The…
A Possible Detection of Occultation by a Proto-planetary Clump in GM Cephei
The YETI Collaboration, W. P. Chen, S. C. -L. Hu +41
GM Cep in the young (~4 Myr) open cluster Trumpler 37 has been known to be an abrupt variable and to have a circumstellar disk with very active accretion. Our monitoring observatio…
YETI follow-up observations of the T Tauri star CVSO30 with transit-like dips
R. Bischoff, St. Raetz, M. Fernández +13
The T Tauri star CVSO30, also known as PTFO8-8695, was studied intensively with ground based telescopes as well as with satellites over the last decade. It showed a variable light…
Transit observations at the observatory in Grossschwabhausen: XO-1b and TrES-1
M. Vanko, St. Raetz, M. Mugrauer +9
We report on observations of transit events of the transiting planets XO-1b and TrES-1 with the AIU Jena telescope in Grossschwabhausen. Based on our IR photometry (in March 2007)…
Planetary transit observations at the University Observatory Jena: TrES-2
St. Raetz, M. Mugrauer, T. O. B. Schmidt +14
We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-Teleskop-Kamera at the University Observatory Jena. Between March 2…
Ground-based transit observations of the HAT-P-18, HAT-P-19, HAT-P-27/WASP-40 and WASP-21 systems
M. Seeliger, M. Kitze, R. Errmann +46
As part of our ongoing effort to investigate transit timing variations (TTVs) of known exoplanets, we monitored transits of the four exoplanets HAT-P-18b, HAT-P-19b, HAT-P-27b/WASP…
Transit timing variation and activity in the WASP-10 planetary system
G. Maciejewski, D. Dimitrov, R. Neuhaeuser +13
Transit timing analysis may be an effective method of discovering additional bodies in extrasolar systems which harbour transiting exoplanets. The deviations from the Keplerian mot…
Observations of the transiting planet TrES-2 with the AIU Jena telescope in GroÃschwabhausen
St. Raetz, M. Mugrauer, T. O. B. Schmidt +9
We have started high precision photometric monitoring observations at the AIU Jena observatory in Grossschwabhausen near Jena in fall 2006. We used a 25 cm Cassegrain telescope equ…
Planetary transit observations at the University Observatory Jena: XO-1b and TrES-1
St. Raetz, M. Mugrauer, T. O. B. Schmidt +9
We report on observations of transit events of the transiting planets XO-1b and TrES-1 with a 25 cm telescope of the University Observatory Jena. With the transit timings for XO-1b…
Photometric monitoring of the young star Par 1724 in Orion
R. Neuhaeuser, A. Koeltzsch, St. Raetz +12
We report new photometric observations of the 200000 year old naked weak-line run-away T Tauri star Par 1724, located north of the Trapezium cluster in Orion. We observed in the br…
On the nature of the candidate T-Tauri star V501 Aurigae
M. VaÅko, G. Torres, L. Hambálek +18
We report new multi-colour photometry and high-resolution spectroscopic observations of the long-period variable V501 Aur, previously considered to be a weak-lined T-Tauri star bel…
Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30
T. O. B. Schmidt, R. Neuhäuser, C. Briceño +11
We surveyed the 25 Ori association for direct-imaging companions. This association has an age of only few million years. Among other targets, we observed CVSO 30, which has recentl…
Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
E. Magaudda, B. Stelzer, K. R. Covey +3
We present a sample of 14 M dwarf stars observed with XMM-Newton and Chandra, for which we also computed rotational periods from Kepler Two-Wheel (K2) Mission light curves. We comp…
The Great Flare of 2021 November 19 on AD Leo. Simultaneous XMM-Newton and TESS observations
B. Stelzer, M. Caramazza, St. Raetz +2
We present a detailed analysis of a superflare on the active M dwarf star AD Leonis. The event presents a rare case of a stellar flare observed simultaneously in X-rays (with XMM-N…
Revisiting parameters for the WASP-1 planetary system
G. Maciejewski, J. Ohlert, D. Dimitrov +8
We present thirteen new transit light curves for the WASP-1 b exoplanet. Observations were acquired with 0.5 - 1.2-m telescopes between 2007 and 2013. Our homogeneous analysis, whi…
New transit observations for HAT-P-30 b, HAT-P-37 b, TrES-5 b, WASP-28 b, WASP-36 b, and WASP-39 b
G. Maciejewski, D. Dimitrov, L. Mancini +14
We present new transit light curves for planets in six extrasolar planetary systems. They were acquired with 0.4-2.2 m telescopes located in west Asia, Europe, and South America. W…
Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin
G. Maciejewski, D. Dimitrov, M. Seeliger +38
The transiting planet WASP-12 b was identified as a potential target for transit timing studies because a departure from a linear ephemeris was reported in the literature. Such dev…
A search for transit timing variation
G. Maciejewski, R. Neuhaeuser, St. Raetz +3
Photometric follow-ups of transiting exoplanets (TEPs) may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then anal…
Photometric analysis of the eclipsing binary 2MASS 19090585+4911585
St. Raetz, M. Vanko, M. Mugrauer +11
We report on observations of the eclipsing binary 2MASS 19090585+4911585 with the 25 cm auxiliary telescope of the University Observatory Jena. We show that a nearby brighter star…
Towards the Rosetta Stone of planet formation
G. Maciejewski, R. Neuhaeuser, R. Errmann +18
Transiting exoplanets (TEPs) observed just about 10 Myrs after formation of their host systems may serve as the Rosetta Stone for planet formation theories. They would give strong…
Variability of young stars: Determination of rotational periods of weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region
A. Koeltzsch, M. Mugrauer, St. Raetz +11
We report on observation and determination of rotational periods of ten weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region. Observations were carried out with th…
Transit timing variation in exoplanet WASP-3b
G. Maciejewski, D. Dimitrov, R. Neuhaeuser +7
Photometric follow-ups of transiting exoplanets may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing v…
First eROSITA study of nearby M dwarfs and the rotation-activity relation in combination with TESS
E. Magaudda, Stelzer B., St. Raetz +1
We present the first study of nearby M dwarfs with the ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Russian Spektrum-Roentgen-Gamma mission (SRG). To this…
High-precision photometry of WASP-12 b transits
G. Maciejewski, R. Errmann, St. Raetz +3
The transiting extrasolar planet WASP-12 b was found to be one of the most intensely irradiated exoplanets. It is unexpectedly bloated and is losing mass that may accrete into the…
Follow-up photometry of TrES-3
M. Vanko, G. Maciejewski, M. Jakubik +7
We present new observations of the transiting system TrES-3 obtained from 2009 to 2011 at several observatories. The orbital parameters of the system were re- determined and a new…
The rotation-activity relation of M dwarfs: From K2 to TESS and PLATO
St. Raetz, B. Stelzer, A. Scholz
Studies of the rotation-activity relation of late-type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution. We study the rotation-act…
WASP-14 b: Transit Timing analysis of 19 light curves
St. Raetz, G. Maciejewski, M. Seeliger +11
Although WASP-14 b is one of the most massive and densest exoplanets on a tight and eccentric orbit, it has never been a target of photometric follow-up monitoring or dedicated obs…
Investigation of a transiting planet candidate in Trumpler 37: an astrophysical false positive eclipsing spectroscopic binary star
R. Errmann, G. Torres, T. O. B. Schmidt +50
We report our investigation of the first transiting planet candidate from the YETI project in the young (~4 Myr old) open cluster Trumpler 37. The transit-like signal detected in t…
Analysis of new high-precision transit light curves of WASP-10 b: starspot occultations, small planetary radius, and high metallicity
G. Maciejewski, St. Raetz, N. Nettelmann +4
The WASP-10 planetary system is intriguing because different values of radius have been reported for its transiting exoplanet. The host star exhibits activity in terms of photometr…
Transit analysis of the CoRoT-5, CoRoT-8, CoRoT-12, CoRoT-18, CoRoT-20, and CoRoT-27 systems with combined ground- and space-based photometry
St. Raetz, A. M. Heras, M. Fernández +2
We have initiated a dedicated project to follow-up with ground-based photometry the transiting planets discovered by CoRoT in order to refine the orbital elements, constrain their…
CoRoT-18 b: Analysis of high-precision transit light curves with starspot features
St. Raetz, A. M. Heras, P. Gondoin +4
When a planet occults a spotty area on a stellar surface, the flux increases and a characteristic feature in a light curve - a bump - is observed. Among the planets detected by the…
Complete X-ray census of Mdwarfs in the solar Neighborhood I. GJ 745 AB: Coronal-hole Stars in the 10 pc Sample
M. Caramazza, B. Stelzer, E. Magaudda +4
We have embarked in a systematic study of the X-ray emission in a volume-limited sample of M dwarf stars, in order to explore the full range of activity levels present in their cor…
Rotation-activity relations and flares of M dwarfs with K2 long- and short-cadence data
St. Raetz, B. Stelzer, M. Damasso +1
Using light curves obtained by the K2 mission, we study the relation between stellar rotation and magnetic activity with special focus on stellar flares. Our sample comprises 56 br…
Young Exoplanet Transit Initiative (YETI)
R. Neuhäuser, R. Errmann, A. Berndt +80
We present the Young Exoplanet Transit Initiative (YETI), in which we use several 0.2 to 2.6m telescopes around the world to monitor continuously young (< 100 Myr), nearby (< 1 kpc…
First eROSITA-TESS results for M dwarfs: Mass dependence of the X-ray activity rotation relation and an assessment of sensitivity limits
E. Magaudda, B. Stelzer, St. Raetz
We present a study of the activity-rotation relation for M dwarf stars, using new X-ray data from the ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Russian…
Transit timing of TrES-2: a combined analysis of ground- and space-based photometry
St. Raetz, G. Maciejewski, Ch. Ginski +21
Homogeneous observations and careful analysis of transit light curves can lead to the identification of transit timing variations (TTVs). TrES-2 is one of few exoplanets, which off…
Transitions in magnetic behavior at the substellar boundary
E. Magaudda, B. Stelzer, R. A. Osten +3
We aim at advancing our understanding of magnetic activity and the underlying dynamo mechanism at the end of the main-sequence. To this end, we collected simultaneous X-ray and rad…
The search for transiting planets using the YETI network
R. Errmann, St. Raetz, M. Kitze +2
To search for young transiting planets in continuous light curves, we monitor young open clusters (2-200 Myr) with the YETI network. Here we report the first transiting candidates…
New photometric observations of the transiting extrasolar planet TrES-3b
M. VaÅko, M. JakubÃk, T. KrejÄová +7
We present new transit observations of the transiting exoplanet TrES-3b obtained in the range 2009 -- 2011 at several observatories. The orbital parameters of the system were redet…
No variations in transit times for Qatar-1 b
G. Maciejewski, M. Fernández, F. J. Aceituno +11
The transiting hot Jupiter planet Qatar-1 b was presented to exhibit variations in transit times that could be of perturbative nature. A hot Jupiter with a planetary companion on a…
Diagnosing the Clumpy Protoplanetary Disk of the UXor Type Young Star GM Cephei
P. C. Huang, W. P. Chen, M. Mugrauer +29
UX Orionis stars (UXors) are Herbig Ae/Be or T Tauri stars exhibiting sporadic occultation of stellar light by circumstellar dust. GM\,Cephei is such a UXor in the young (~M…