Publications (75)
Long-term variations in the X-ray activity of HR 1099
V. Perdelwitz, F. H. Navarrete, J. Zamponi +6
Although timing variations in close binary systems have been studied for a long time, their underlying causes are still unclear. A possible explanation is the so-called Applegate m…
X-ray accretion signatures in the close CTTS binary V4046 Sgr
H. M. Günther, C. Liefke, J. H. M. M. Schmitt +2
We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr. The He-like triplets of O VII, Ne IX, and Si XIII are clearly detected. Similar to the CTTS TW…
Neon and oxygen in low activity stars: towards a coronal unification with the Sun
J. Robrade, J. H. M. M. Schmitt, F. Favata
The disagreement between helioseismology and a recent downward revision of solar abundances has resulted in a controversy about the true neon abundance of the Sun and other stars.…
X-rays from RU Lupi - Accretion and winds in CTTS
J. Robrade, J. H. M. M. Schmitt
Using three XMM-Newton observations we study the X-ray emission of RU Lup, a accreting and wind-driving CTTS. In comparison with other bright CTTS we study possible signatures of a…
The SRG X-ray orbital observatory, its telescopes and first scientific results
R. Sunyaev, V. Arefiev, V. Babyshkin +39
The orbital observatory Spectrum-Roentgen-Gamma (SRG), equipped with the grazing-incidence X-ray telescopes Mikhail Pavlinsky ART-XC and eROSITA, was launched by Roscosmos to the L…
Coronal and chromospheric activity of Teegarden's star
B. Fuhrmeister, J. H. M. M. Schmitt, A. Reienrs +10
Teegarden's star is a late-type M-dwarf planet host, typically showing only rather low levels of activity. In this paper we present an extensive characterisation of this activity a…
SRG/eROSITA 3D mapping of the ISM using X-ray absorption spectroscopy
E. Gatuzz, J. Wilms, A. Zainab +6
We present a detailed study of the hydrogen density distribution in the local interstellar medium (ISM) using the X-ray absorption technique. Hydrogen column densities were precise…
X-raying the Sco-Cen OB association: The low-mass stellar population revealed by eROSITA
J. H. M. M. Schmitt, S. Czesla, S. Freund +2
We present the results of the first X-ray all-sky survey (eRASS1) performed by the eROSITA instrument on board the Spectrum-Roentgen-Gamma (SRG) observatory of the Sco-Cen OB assoc…
X-ray properties of active M dwarfs as observed by XMM-Newton
J. Robrade, J. H. M. M. Schmitt
We present a comparative study of X-ray emission from a sample of active M dwarfs with spectral types \hbox{M3.5 - M4.5} using XMM-Newton observations of two single stars, AD Leoni…
Multiepoch, multiwavelength study of accretion onto T Tauri: X-ray versus optical and UV accretion tracers
P. C. Schneider, H. M. Günther, J. Robrade +2
Classical T Tauri stars (CTTSs) accrete matter from the inner edge of their surrounding circumstellar disks. The impact of the accretion material on the stellar atmosphere results…
The auroral radio emission of the magnetic B-type star rho OphC
P. Leto, C. Trigilio, C. S. Buemi +19
The non-thermal radio emission of main-sequence early-type stars is a signature of stellar magnetism. We present multi-wavelength (1.6-16.7 GHz) ATCA measurements of the early-type…
Spatially resolved X-ray emission of EQ Pegasi
J. Robrade, J. -U. Ness, J. H. M. M. Schmitt
We present an analysis of an XMM-Newton observation of the M dwarf binary EQ Pegasi with a special focus on the the spatial structure of the X-ray emission and the analysis of ligh…
Discovery of a Supercluster in the eROSITA Final Equatorial Depth Survey: X-ray Properties, Radio Halo, and Double Relics
V. Ghirardini, E. Bulbul, D. N. Hoang +27
We examine the X-ray, optical, and radio properties for the members clusters of a new supercluster discovered during the SRG/eROSITA Performance Verification phase. In the 140 deg2…
eROSITA Science Book: Mapping the Structure of the Energetic Universe
A. Merloni, P. Predehl, W. Becker +22
eROSITA is the primary instrument on the Russian SRG mission. In the first four years of scientific operation after its launch, foreseen for 2014, it will perform a deep survey of…
The high energy spectrum of Proxima Centauri simultaneously observed at X-ray and FUV wavelengths
B. Fuhrmeister, A. Zisik, P. C. Schneider +6
The M dwarf Proxima~Centauri is known to be magnetically active and it hosts a likely Earth-like planet in its habitable zone. Understanding the characteristics of stellar radiatio…
The Abell 3391/95 galaxy cluster system: A 15 Mpc intergalactic medium emission filament, a warm gas bridge, infalling matter clumps, and (re-) accelerated plasma discovered by combining SRG/eROSITA data with ASKAP/EMU and DECam data
T. H. Reiprich, A. Veronica, F. Pacaud +44
We used dedicated SRG/eROSITA X-ray, ASKAP/EMU radio, and DECam optical observations of a 15 sq.deg region around the interacting galaxy cluster system A3391/95 to study the warm-h…
51 Pegasi - a planet-bearing Maunder minimum candidate
K. Poppenhaeger, J. Robrade, J. H. M. M. Schmitt +1
We observed 51 Peg, the first detected planet-bearing star, in a 55 ks XMM-Newton pointing and in 5 ks pointings each with Chandra HRC-I and ACIS-S. The star has a very low count r…
eROSITA all-sky survey - stars and optical loading
J. Robrade, K. Dennerl, M. J. Freyberg +1
The paper investigates how bright stars cause optical loading in the eROSITA all‑sky X‑ray survey, characterizes the resulting spurious sources, and provides conversion factors and…
MN Lup: X-rays from a weakly accreting T Tauri star
H. M. Guenther, U. Wolter, J. Robrade +1
Young T Tauri stars (TTS) are surrounded by an accretion disk, which over time disperses due to photoevaporation, accretion, and possibly planet formation. The accretion shock on t…
Altair - the 'hottest' magnetically active star in X-rays
J. Robrade, J. H. M. M. Schmitt
The A7 star Altair is one of the hottest magnetically active stars. Its proximity to the Sun allows a detailed investigation of a corona in X-rays for a star with a shallow convect…
Doppler imaging an X-ray flare on the ultrafast rotator BO Mic - A contemporaneous multiwavelength study using XMM-Newton and VLT
U. Wolter, J. Robrade, J. H. M. M. Schmitt +1
We present an analysis of contemporaneous photospheric, chromospheric and coronal structures on the highly active K-dwarf star BO Mic (Speedy Mic). We localize a moderate flare in…
The eROSITA Final Equatorial-Depth Survey (eFEDS). The stellar counterparts of eROSITA sources identified by machine learning and Bayesian algorithms
P. C. Schneider, S. Freund, S. Czesla +3
Stars are ubiquitous X-ray emitters and will be a substantial fraction of the X-ray sources detected in the on-going all-sky survey performed by the eROSITA instrument aboard the S…
eROSITA's cool star population explained
J. H. M. M. Schmitt, P. C. Schneider, S. Czesla +2
The rotation-activity connection is the standard paradigm for interpreting chromospheric and coronal activity in late-type stars, namely, stars with outer convection zones. This pa…
The eROSITA Final Equatorial-Depth Survey (eFEDS): The variability catalogue and multi-epoch comparison
Th. Boller, J. H. M. M. Schmitt, J. Buchner +10
The 140 square degree Final Equatorial-Depth Survey (eFEDS) field, observed with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) aboard the Spectrum-Roentgen…
Quiescent and flaring X-ray emission from the nearby M/T dwarf binary SCR 1845-6357
J. Robrade, K. Poppenhaeger, J. H. M. M. Schmitt
We investigate an XMM-Newton observation of SCR 1845-6357, a nearby, ultracool M8.5/T5.5 dwarf binary. The binary is unresolved in the XMM detectors, however the X-ray emission is…
X-ray emission from the M9 dwarf 1RXS J115928.5-524717 - Quasi-quiescent coronal activity at the end of the main sequence
J. Robrade, J. H. M. M. Schmitt
Methods: We analyse an XMM-Newton observation of 1RXS J115928.5-524717, an ultracool dwarf with spectral type M9 and compare its X-ray properties to those of other similar very lat…
Coronal and chromospheric emission in A-type stars
Hans Moritz Günther, Carl Melis, J. Robrade +3
Cool stars on the main sequence generate X-rays from coronal activity, powered by a convective dynamo. With increasing temperature, the convective envelope becomes smaller and X-ra…
A deep XMM-Newton X-ray observation of the Chamaeleon I dark cloud
J. Robrade, J. H. M. M. Schmitt
Methods. The northern-eastern fringe of the Chameleon I dark cloud was observed with XMM-Newton, revisiting a region observed with ROSAT 15 years ago. Centered on the extended X-ra…
The nature of the 2014-2015 dim state of RW Aur revealed by X-ray, optical, and NIR observations
P. C. Schneider, H. M. Günther, J. Robrade +7
The binary system RW Aur consists of two classical T~Tauri stars (CTTSs). The primary recently underwent its second observed major dimming event (mag). We present new…
HST FUV imaging of DG Tau: Fluorescent molecular hydrogen emission from the wide angle outflow
P. C. Schneider, J. Eisloeffel, M. Guedel +4
One of the best-studied jets from all young stellar objects is the jet of DG Tau, which we imaged in the FUV with HST for the first time. These high spatial resolution images were…
X-ray to NIR emission from AA Tauri during the dim state - Occultation of the inner disk and gas-to-dust ratio of the absorber
P. C. Schneider, K. France, H. M. Günther +5
AA Tau is a well-studied, nearby classical T Tauri star, which is viewed almost edge-on. A warp in its inner disk periodically eclipses the central star, causing a clear modulation…
X-ray emission from classical T Tauri stars: Accretion shocks and coronae?
H. M. Guenther, J. H. M. M. Schmitt, J. Robrade +1
Classical T Tauri stars (CTTS) are surrounded by actively accreting disks. According to current models material falls along the magnetic field lines from the disk with more or less…
The stellar content of the ROSAT all-sky survey
S. Freund, S. Czesla, J. Robrade +2
We present and apply a method to identify the stellar content of the ROSAT all-sky survey (RASS). We performed a crossmatch between the RASS sources and stellar candidates selected…
Evidence for radio and X-ray auroral emissions from the magnetic B-type star rho Oph A
P. Leto, C. Trigilio, F. Leone +20
We present new ATCA multi-wavelength radio measurements (range 2.1-21.2 GHz) of the early-type magnetic star rho Oph A, performed in March 2019 during 3 different observing session…
The high-energy environment of the heavy sub-Earth GJ 367 b indicates likely complete evaporation of its atmosphere
K. Poppenhaeger, L. Ketzer, N. Ilic +5
The planet GJ 367 b is a recently discovered high-density sub-Earth orbiting an M dwarf star. Its composition was modelled to be predominantly iron with a potential remainder of a…
The stellar corona-chromosphere connection. A comprehensive study of X-ray and Ca II IRT fluxes from eROSITA and Gaia
S. Freund, S. Czesla, B. Fuhrmeister +4
Stellar activity can be observed at different wavelengths in a variety of different activity indicators. We investigated the correlation between coronal and chromospheric emissions…
X-ray emission from the remarkable A-type star HR 8799
J. Robrade, J. H. M. M. Schmitt
We present a Chandra observation of the exceptional planet bearing A5V star HR 8799, more precisely classified as a kA5hF0mA5 star and search for intrinsic X-ray emission. We clear…
DN Tauri - coronal activity and accretion in a young low-mass CTTS
J. Robrade, M. Guedel, H. M. Guenther +1
We present a deep XMM-Newton observation of DN Tau, a young M0-type accreting CTTS and investigate its X-ray properties and X-ray generating mechanisms. Specifically we examine the…
X-ray activity cycles in stellar coronae
J. Robrade, J. H. M. M. Schmitt, A. Hempelmann
We present updated results from the ongoing XMM-Newton monitoring program of moderately active, solar-like stars to investigate stellar X-ray activity cycles; here we report on the…
Counterpart identification and classification for eRASS1 and characterisation of the AGN content
M. Salvato, J. Wolf, T. Dwelly +44
[abridged] Accurately accounting for the AGN phase in galaxy evolution requires a large, clean AGN sample. This is now possible with SRG/eROSITA. The public Data Release 1 (DR1, Ja…
The SRG/eROSITA All-Sky Survey DR2: Cumulative X-ray catalogues from the first three surveys and multi-wavelength counterparts in the western Galactic hemisphere
M. E. Ramos-Ceja, G. Lamer, M. Salvato +111
The paper presents the second data release of the SRG/eROSITA all‑sky survey, providing catalogues of nearly two million X‑ray sources (point‑like and extended) from the first thre…
HST FUV C IV observations of the hot DG Tauri jet
P. C. Schneider, J. Eisloeffel, M. Guedel +4
Protostellar jets are tightly connected to the accretion process and regulate the angular momentum balance of accreting star-disk systems. The DG Tau jet is one of the best-studied…
New X-ray observations of IQ Aurigae and alpha2 Canum Venaticorum - Probing the magnetically channelled wind shock model in A0p stars
J. Robrade, J. H. M. M. Schmitt
We present new X-ray observations of the A0p stars alpha^2 CVn (log Lx < 26.0 erg/s) and IQ Aur (log Lx = 29.6 erg/s) and find that their X-ray luminosities differ by at least thre…
Further X-ray detections of Herbig stars
B. Stelzer, J. Robrade, J. H. M. M. Schmitt +1
The interpretation of X-ray detections from Herbig Ae/Be stars is disputed as it is not clear if these intermediate-mass pre-main sequence stars are able to drive a dynamo and ensu…
The stellar content of the XMM-Newton slew survey
S. Freund, J. Robrade, C. Schneider +1
We present a detailed analysis of the stellar content of the current version of the XMM-Newton slew survey (XMMSL2). Since stars emit only a small fraction of their total luminosit…
ESO-Athena Synergy White Paper
P. Padovani, F. Combes, M. Diaz Trigo +29
The Advanced Telescope for High ENergy Astrophysics (Athena) is the X-ray observatory mission selected by ESA within its Cosmic Vision 2015-2025 programme to address the Hot and En…
Coronal activity cycles in action - X-rays from alpha Centauri A/B
J. Robrade, J. H. M. M. Schmitt
We report on the coronal activity cycles of our stellar neighbors alpha Centauri A/B. The binary has been monitored with XMM-Newton since 2002 to study the long-term evolution of c…
The eROSITA DR1 variability catalogue
Th. Boller, M. Salvato, J. Buchner +14
With its first All-Sky Survey (eRASS1), the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spectrum-Roentgen-Gamma (SRG) mission has offered an unp…
Detection of Saturnian X-ray emission with XMM-Newton
J. -U. Ness, J. H. M. M. Schmitt, J. Robrade
The giant planet Saturn was observed by XMM-Newton in September 2002. We present and analyse these XMM-Newton observations and compare our findings to the Chandra observations of S…
The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
A. Merloni, G. Lamer, T. Liu +142
The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying the sky in December 2019, with the aim of producing all-sky X-ray source lists and sk…
The eROSITA X-ray telescope on SRG
P. Predehl, R. Andritschke, V. Arefiev +90
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on the Spectrum-Roentgen-Gamma (SRG) mission, which was successfully launched on July 1…
The SRG/eROSITA all-sky survey -- Identifying the coronal content with HamStar
S. Freund, S. Czesla, P. Predehl +6
The first eROSITA all-sky survey (eRASS1) performed on board the Spectrum-Roentgen-Gamma mission (SRG) provides more than 900,000 X-ray sources in the 0.2 - 2.3 keV band located in…
Quiescent X-ray emission from the M9 dwarf LHS 2065
J. Robrade, J. H. M. M. Schmitt
We investigate an archival XMM-Newton observation of LHS 2065, an ultracool dwarf with spectral type M9. We clearly detect LHS 2065 at soft X-ray energies in less than 1 h effectiv…
Outstanding X-ray emission from the stellar radio pulsar CU Virginis
J. Robrade, L. M. Oskinova, J. H. M. M. Schmitt +2
We present X-ray observations of CU Vir performed with XMM-Newton and Chandra. With Lx = 3 x 10^28 erg/s the source is moderately X-ray bright, but its spectrum is extremely hard c…
X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Tri
V. Perdelwitz, S. Czesla, J. Robrade +2
Close binary systems provide an excellent tool to determine stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most…
X-ray counterparts to stellar MeerKAT Galactic-plane compact radio sources
O. D. Egbo, P. J. Groot, D. A. H. Buckley +5
Radio emission from magnetically active stars arises mainly from non-thermal processes and complements high-energy X-ray emission. Sensitive, wide-field radio and X-ray surveys now…
The SRG/eROSITA all-sky survey: Cosmology constraints from cluster abundances in the western Galactic hemisphere
V. Ghirardini, E. Bulbul, E. Artis +46
The cluster mass function traces the growth of linear density perturbations and provides valuable insights into the growth of structures, the nature of dark matter, and the cosmolo…
eROSITA X-ray scan of the eta Chamaeleontis cluster
J. Robrade, S. Czesla, S. Freund +2
The nearby young open cluster eta Chamaeleontis has been observed by eROSITA/SRG during its CalPV phase for 150 ks. The eROSITA data were taken in the field-scan mode, an observing…
The X-ray view of the Hyades cluster: updated
S. Freund, J. Robrade, P. C. Schneider +1
We revisit the X-ray properties of the main-sequence Hyades members and the relation between X-ray emission and stellar rotation. As input catalog for Hyades members, we combined t…
Fifteen years in the high-energy life of the solar-type star HD 81809. XMM-Newton observations of a stellar activity cycle
S. Orlando, F. Favata, G. Micela +5
Aims. The data set of the long-term XMM-Newton monitoring program of HD 81809 is analyzed to study its X-ray cycle, to investigate if the latter is related to the chromospheric one…
''Forbidden" stars in the eROSITA all-sky survey: X-ray emission from very late-type giants
J. H. M. M. Schmitt, M. Hünsch, P. C. Schneider +4
We present the results of the first X-ray all-sky survey (eRASS1) performed by the eROSITA instrument onboard the Spectrum-Roentgen-Gamma (SRG) mission on X-ray emitting red giants…
X-rays from Alpha Centauri - The darkening of the solar twin
J. Robrade, J. H. M. M. Schmitt, F. Favata
We present first results from five XMM-Newton observations of the binary system Alpha Centauri, which has been observed in snapshot like exposures of roughly two hours each during…
Discovery and origin of the radio emission from the multiple stellar system KQVel
P. Leto, L. M. Oskinova, C. S. Buemi +20
KQVel is a binary system composed of a slowly rotating magnetic Ap star with a companion of unknown nature. In this paper, we report the detection of its radio emission. We conduct…
The near-infrared companion to HD94660 (=KQ Vel)
M. Schöller, C. A. Hummel, S. Hubrig +4
The Bp star HD94660 is a single-lined spectroscopic binary. Some authors have suggested that the unseen companion of at least 2M_sun may be a compact object. We intend to study thi…
Coronal activity cycles in nearby G and K stars - XMM-Newton monitoring of 61 Cygni and Alpha Centauri
J. Robrade, J. H. M. M. Schmitt, F. Favata
We use X-ray observations of the nearby binaries 61 Cyg A/B (K5V and K7V) and Alpha Cen A/B (G2V and K1V) to study the long-term evolution of magnetic activity in weakly to moderat…
Coronal properties of planet-bearing stars
K. Poppenhaeger, J. Robrade, J. H. M. M. Schmitt
Do extrasolar planets affect the activity of their host stars? Indications for chromospheric activity enhancement have been found for a handful of targets, but in the X-ray regime,…
eROSITA on SRG: a X-ray all-sky survey mission
N. Cappelluti, P. Predehl, H. Boehringer +23
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late…
X-rays from accretion shocks in T Tauri stars: The case of BP Tau
J. H. M. M. Schmitt, J. Robrade, J. -U. Ness +2
We present an XMM-Newton observation of the classical T Tauri star BP Tau. In the XMM-Newton RGS spectrum the O {\sc vii} triplet is clearly detected with a very weak forbidden lin…
The X-ray catalogue of FGK stars within 10 pc: The coronal temperature-brightness relation explained with the RTV scaling law
M. M. Bennedik, B. Stelzer, M. Caramazza +3
The authors compile an X‑ray catalog of FGK main‑sequence stars within 10 pc, derive coronal temperatures and X‑ray fluxes from eROSITA, XMM‑Newton and ROSAT data, and show that th…
XMM-Newton X-ray spectroscopy of classical T Tauri stars
J. Robrade, J. H. M. M. Schmitt
We present results from a comparative study of XMM-Newton observations of four classical T Tauri stars (CTTS), namely BP Tau, CR Cha, SU Aur and TW Hya. In these objects coronal, i…
The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
H. Brunner, T. Liu, G. Lamer +35
Context. The eROSITA X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) observatory combines a large field of view and collecting area in the energy range 0.2 to $\si…
A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
P. Leto, C. Trigilio, J. Krticka +20
In this paper, we present the analysis of incoherent non-thermal radio emission from a sample of hot magnetic stars, ranging from early-B to early-A spectral type. Spanning a wide…
Proxima Centauri -- the nearest planet host observed simultaneously with AstroSat, Chandra and HST
S. Lalitha, J. H. M. M. Schmitt, K. P. Singh +6
Our nearest stellar neighbour, Proxima Centauri, is a low mass star with spectral typedM5.5 and hosting an Earth-like planet orbiting within its habitable zone. However, the habita…
Soft coronal X-rays from β Pictoris
H. M. Günther, S. J. Wolk, J. J. Drake +3
A type stars are expected to be X-ray dark, yet weak emission has been detected from several objects in this class. We present new Chandra/HRC-I observations of the A5 V star β Pi…
The corona -- chromosphere connection studied with simultaneous eROSITA and TIGRE observations
B. Fuhrmeister, J. Robrade, J. N. Gonzalez-Perez +3
Stellar activity is inherently time variable, therefore simultaneous measurements are necessary to study the correlation between different activity indicators. In this study we com…