D. Froebrich
A5083438596- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Phase Equilibria and Thermodynamics
- Atomic and Molecular Physics
- Reservoir Engineering and Simulation Methods
- Advanced Thermodynamic Systems and Engines
- Superconducting Materials and Applications
- Adaptive optics and wavefront sensing
- Space Exploration and Technology
- Image Processing Techniques and Applications
- Geomagnetism and Paleomagnetism Studies
- Remote Sensing and LiDAR Applications
- Laser-Plasma Interactions and Diagnostics
- Superconducting and THz Device Technology
- Historical Geography and Cartography
University of Kent
2015-2024
Dublin Institute For Advanced Studies
2003-2007
Thüringer Landessternwarte Tautenburg
2000-2003
The APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) is an unbiased 870 μm submillimetre survey inner Galactic plane (|ℓ| < 60° with |b| 1|$_{.}^{\circ}$|5). It largest and most sensitive ground-based wavelength to date has provided a large systematic inventory all massive, dense clumps in (≥1000 M⊙ at heliocentric distance 20 kpc) includes representative samples earliest embedded stages high-mass star formation. Here, we present first detailed census properties (velocities,...
We used star density maps obtained from 2MASS to obtain a sample of clusters in the entire Galactic Plane with |b|<20deg. A total 1788 cluster candidates are identified this survey. Among those 681 previously known open and 86 globular clusters. statistical analysis indicates that our 1021 new has contamination about 50%. Star parameters by fitting King profile density. These statistically identify probable sample. detailed investigation projected distribution Galaxy demonstrates they...
We present wide-field near-infrared (IR) images of the DR21/W75 high-mass star-forming region, obtained with Wide Field Camera (WFCAM) on United Kingdom Infrared Telescope. Broad-band JHK and narrow-band H2 1-0S(1) are compared to archival mid-IR from Spitzer Space Telescope, 850-μm dust-continuum maps Submillimeter Common User Bolometer Array (SCUBA). Together these data give a complete picture dynamic star formation across this extensive which includes at least four separate sites in...
This paper defines the UK Infra-Red Telescope (UKIRT) Hemisphere Survey (UHS) and release of remaining ~12,700 sq.deg J-band survey data products. The UHS will provide continuous J K-band coverage in northern hemisphere from a declination 0 deg to 60 by combining existing Large Area Survey, Galactic Plane Clusters conducted under UKIRT Infra-red Deep Sky (UKIDSS) programme with this new additional area not covered UKIDSS. released includes imaging source catalogues over area, which, together...
Context. Since July 2014, the Gaia mission has been engaged in a high-spatial-resolution, time-resolved, precise, accurate astrometric, and photometric survey of entire sky. Aims. We present Science Alerts project, which operation since 1 June 2016. describe system developed to enable discovery publication transient events as seen by . Methods. outline data handling, timings, performances, we detection algorithms filtering procedures needed manage high false alarm rate. identify two classes...
GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50 years of study. In this paper, we present observations X-ray and optical domains after obtained by GRANDMA Collaboration (which includes from 30 professional amateur telescopes) Insight-HXMT Collaboration. We study afterglow with empirical fitting GRANDMA+HXMT data, augmented data literature up to 60 days. then model numerically, using a Bayesian approach, HXMT-LE observations, that augment Swift-XRT additional...
ABSTRACT During the pre-main-sequence (pre-MS) evolution stage of a star, significant amounts stellar mass are accreted during episodic accretion events, such as multidecade FUor-type outbursts. Here, we present near-infrared spectroscopic follow-up study 33 high-amplitude (most with ΔKs &gt; 4 mag) variable sources discovered by Vista Variables in Via Lactea (VVV) survey. Based on spectral features, 25 classified eruptive young objects (YSOs), including 15 newly identified FUors, six...
VISTA Variables in the V\'{\i}a L\'actea (VVV) is one of six ESO Public Surveys operating on new 4-meter Visible and Infrared Survey Telescope for Astronomy (VISTA). VVV scanning Milky Way bulge an adjacent section disk, where star formation activity high. One principal goals to find clusters different ages. In order trace early epochs cluster we concentrated our search directions those known regions, masers, radio, infrared sources. The disk area covered by was visually inspected using...
Accretion in young stellar objects (YSOs) is at least partially episodic, i.e. periods with high accretion rates ('bursts') are interspersed by quiescent phases. These bursts manifest themselves as eruptive variability. Here we present a systematic survey for YSOs aiming to constrain the frequency of bursts. We compare mid-infrared photometry from Spitzer and WISE separated ~5 yr two samples YSOs, nearby star forming regions Galactic plane, each comprising about 4000 sources. All which...
We present the discovery of 816 high amplitude infrared variable stars ($\Delta K_{\rm s} >$ 1 mag) in 119 deg$^2$ Galactic midplane covered by Vista Variables Via Lactea (VVV) survey. Almost all are new discoveries and about 50$\%$ YSOs. This provides further evidence that YSOs commonest plane. In 2010-2014 time series likely we find variability increases towards younger evolutionary classes (class I flat-spectrum sources) except on short timescales ($<$25 days) where this trend is...
In a companion work (Paper I) we detected large population of highly variable Young Stellar Objects (YSOs) in the Vista Variables Via Lactea (VVV) survey, typically with class I or flat spectrum spectral energy distributions and diverse light curve types. Here present infrared spectra (0.9--2.5 $\mu$m) 37 these variables, many them observed bright state. The confirm that 15/18 sources eruptive curves have signatures high accretion rate, either showing EXor-like emission features ($\Delta$v=2...
Abstract We report on the source Gaia 17bpi and identify it as a new, ongoing FU Ori–type outburst, associated with young stellar object. The optical light curve from exhibited 3.5 mag rise appearing to plateau in mid-/late 2018. Mid-infrared observations NEOWISE also show >3 that occurred two stages, second one coincident brightening, first preceding brightening by ∼1.5 yr. model outburst having started between October December of 2014. This wavelength-dependent aspect star...
The formation of stars is inextricably linked to the structure their parental molecular clouds. Here we take a number nearby giant clouds (GMCs) and analyse column density mass distributions. This investigation based on four new all-sky median colour excess extinction maps determined from 2MASS. span range spatial resolution factor eight. allows us determine cloud properties at common scale 0.1pc, as well study dependence properties. We find that low turbulence dominated part can be fit by...
We are studying the column density distribution of all nearby giant molecular clouds. As part this project, we generated several all-sky extinction maps. They calculated using median near-infrared colour excess technique applied to data from Two-Micron All-Sky Survey. Our large-scale approach allows us fit spline functions extinction-free regions in order accurately determine values. Two types maps presented: (i) with a constant noise and variable spatial resolution (ii) noise. standardAV...
We present the goals and preliminary results of an unbiased, near-infrared, narrow-band imaging survey first galactic quadrant (10° < l 65°; −13 b +13). This area includes most giant molecular clouds massive star forming regions in Northern hemisphere. The is centred on 1–0 S(1) rovibrational line H2, a proven tracer hot, dense gas star-forming regions, around evolved stars, supernova remnants. observations complement existing upcoming photometric surveys (Spitzer-GLIMPSE, UKIDSS-GPS,...
Context. An earlier analysis of the Milky Way Star Cluster (MWSC) catalogue revealed an apparent lack old (t ≳ 1 Gyr) open clusters in solar neighbourhood (d ≲ kpc).
We use deep multi-epoch near-IR images of the VISTA Variables in V\'ia L\'actea (VVV) Survey to search for RR Lyrae stars towards Southern Galactic plane. Here we report discovery a group close together VVV tile d025. Inspection and PSF photometry reveals that most these are likely belong globular cluster, matches position previously known star cluster FSR\,1716. The stellar density map field yields $>100$ sigma detection this candidate is centered at equatorial coordinates...
Abstract The Hubble UV Legacy Library of Young Stars as Essential Standards (ULLYSES) Director’s Discretionary Program low-mass pre-main-sequence stars, coupled with forthcoming data from Atacama Large Millimeter/submillimeter Array and James Webb Space Telescope, will provide the foundation to revolutionize our understanding relationship between young stars their protoplanetary disks. A comprehensive evaluation physics disk evolution planet formation requires intricate relationships mass...
We have performed a comprehensive search of VISTA Variables in the Via Lactea (VVV) database 9.5 yr light curves for variable sources with $\Delta K_s \ge 4$ mag, aiming to provide large sample high amplitude eruptive young stellar objects (YSOs) and detect unusual or new types infrared source. find 222 transient Galactic bulge disc, most which are discoveries. The mainly comprises novae, YSOs, microlensing events, Long Period Variable stars (LPVs) few rare unclassified sources....
Context. The ESO public survey VISTA Variables in the Vía Láctea (VVV) surveyed inner Galactic bulge and adjacent southern disk from 2009–2015. Upon its conclusion, complementary VVV extended (VVVX) has expanded both temporal as well spatial coverage of original area, widening it 562 to 1700 sq. deg., providing additional epochs JHK s filters 2016–2023. Aims. With completion VVVX observations during first semester 2023, we present here observing strategy, a description data quality access,...
<i>Aims. <i/>A census of molecular hydrogen flows across the entire Orion A giant cloud is sought. With this paper we aim to associate each flow with its progenitor and associated core, so that characteristics outflows outflow sources can be established.<i>Methods. <i/>We present wide-field near-infrared images A, obtained Wide Field Camera, WFCAM, on United Kingdom Infrared Telescope. Broad-band K narrow-band H<sub>2<sub/> 1-0S(1) a contiguous ~8 square degree region are compared mid-IR...
Until now, it has been impossible to observationally measure how star cluster scaleheight evolves beyond 1 Gyr as only small samples have available. Here, we establish a novel method determine the of sample using modelled distributions and Kolmogorov–Smirnov tests. This allows us with 25 per cent accuracy for 38 clusters or more. We apply our investigate temporal evolution scaleheight, homogeneously selected sub-samples Kharchenko et al. (MWSC), Dias (DAML02), WEBDA, Froebrich (FSR)....
We report the discovery and characterisation of a deeply eclipsing AM CVn-system, Gaia14aae (= ASSASN-14cn). was identified independently by All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al. 2014) Gaia Science Alerts project, during two separate outbursts. A third outburst is seen in archival Pan-STARRS-1 (PS1; Schlafly 2012; Tonry Magnier 2013) ASAS-SN data. Spectroscopy reveals hot, hydrogen-deficient spectrum with clear double-peaked emission lines, consistent an accreting...