A5074837101- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- Advanced Combustion Engine Technologies
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Atomic and Molecular Physics
- Astrophysics and Cosmic Phenomena
- Space Exploration and Technology
- Gamma-ray bursts and supernovae
- Chemical Thermodynamics and Molecular Structure
- Geophysics and Gravity Measurements
- Bee Products Chemical Analysis
- Advanced Chemical Physics Studies
- Global Energy and Sustainability Research
- Phase Equilibria and Thermodynamics
- Geomagnetism and Paleomagnetism Studies
- Tribology and Lubrication Engineering
- Astronomical and nuclear sciences
- High-pressure geophysics and materials
Centro de Astrobiología
2011-2024
University of Leeds
2014-2018
Clemson University
2013-2014
Universidad Autónoma de Madrid
2011-2013
Unidades Centrales Científico-Técnicas
2010-2013
Consejo Superior de Investigaciones Científicas
2010-2013
UK Astronomy Technology Centre
2010
Royal Observatory
2010
European Space Astronomy Centre
2010
Herbig Ae/Be stars span a key mass range that links low and high stars, thus provide an ideal window from which to explore their formation. This paper presents VLT/X-Shooter spectra of 91 HAeBes; the largest spectroscopic study HAeBe accretion date. A homogeneous approach determining stellar parameters is undertaken for majority sample. Measurements ultra-violet (UV) are modelled within context magnetospheric accretion, allowing direct determination rates. Multiple correlations observed...
We use Gaia Data Release 2 (DR2) to place 252 Herbig Ae/Be stars in the HR diagram and investigate their characteristics properties. For all known with parallaxes DR2, we collected atmospheric parameters photometric extinction values from literature. To these data added near- mid-infrared photometry, H$\alpha$ equivalent widths line profiles, binarity status. In addition, developed a variability indicator Gaia's DR2 information. provide masses, ages, luminosities, distances, variabilities...
This work aims to derive accretion rates for a sample of 38 HAeBe stars. We apply magnetospheric (MA) shock modelling reproduce the observed Balmer excesses. look possible correlations with strength Halpha, [OI]6300, and Brgamma emission lines. The median mass rate is 2 x 10^-7 Msun yr^-1 in our sample. model fails large excesses shown by four hottest stars (T* > 12000 K). Macc propto M*^5 Lacc L*^1.2 sample, scatter. Empirical calibrations relating luminosities are provided. slopes...
We observed a sample of 20 representative Herbig Ae/Be stars and 5 A-type debris discs with PACS onboard Herschel, as part the GAS in Protoplanetary Systems (GASPS) project. The observations were done spectroscopic mode, cover far-infrared lines [O i], [C ii], CO, CH+, H2O, OH. have i] 63 μm detection rate 100% for 0% discs. 145 line is only detected 25% CO J = 18–17 45% (and fewer cases higher transitions) stars, while ii] 157 μm, we often find spatially variable background contamination....
We describe a large-scale far-infrared line and continuum survey of protoplanetary disk through to young debris systems carried out using the ACS instrument on Herschel Space Observatory. This Open Time Key program, known as GASPS (Gas Survey Protoplanetary Systems), targeted ∼250 stars in narrow wavelength regions covering [OI] fine structure at 63 μm brightest such objects. A subset targets were also surveyed [OI]145 μm, [CII] 157 well several transitions H2O high-excitation CO lines...
This work presents a spectroscopic study of 163 Herbig Ae/Be stars. Amongst these, we present new data for 30 objects. Stellar parameters such as temperature, reddening, mass, luminosity and age are homogeneously determined. Mass accretion rates determined from $\rm H\alpha$ emission line measurements. Our is complemented with the X-Shooter sample previous studies update results using Gaia DR2 parallaxes giving total 78 objects stellar mass rates. In addition, an additional 85 HAeBes We...
Herbig Ae/Be stars are intermediate-mass pre-main sequence surrounded by circumstellar dust disks. Some observed to produce jets, whose appearance as a of shock fronts (knots) suggests past episodic outflow variability. This "jet fossil record" can be used reconstruct the history. We present first optical near-infrared (NIR) VLT/X-shooter spectra jet from Ae star HD 163296. determine physical conditions in knots, well their kinematic "launch epochs". Knots formed simultaneously on either...
Context. Debris discs are thought to be formed through the collisional grinding of planetesimals, and can considered as outcome planet formation. Understanding properties gas dust in debris help us comprehend architecture extrasolar planetary systems. Herschel Space Observatory far-infrared (IR) photometry spectroscopy have provided a valuable dataset for study composition. This paper is part series papers devoted PACS observations young stellar associations. Aims. work aims at studying Beta...
Context. Herbig Ae/Be stars (HAeBes) have so far been studied based on relatively small samples that are scattered throughout the sky. Their fundamental stellar and circumstellar parameters statistical properties were derived with heterogeneous approaches before Gaia . Aims. Our main goal is to contribute study of HAeBes from largest sample such sources date, for which determined homogeneously analysis spectral energy distributions (SEDs) EDR3 parallaxes photometry. Methods. Multiwavelength...
The intermediate-mass pre-main sequence Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. study of general properties these objects is hampered by fact that few mostly serendipitously discovered sources known. Our goal identify new candidates create a homogeneous well defined catalogue objects. We have applied machine learning techniques 4,150,983 with data from Gaia DR2, 2MASS, WISE, IPHAS or VPHAS+. Several observables...
The evolution of young stars and disks is driven by the interplay several processes, notably accretion ejection material. Critical to correctly describe conditions planet formation, these processes are best probed spectroscopically. About five-hundred orbits Hubble Space Telescope (HST) being devoted in 2020-2022 ULLYSES public survey about 70 low-mass (M<2Msun) (age<10 Myr) at UV wavelengths. Here we present PENELLOPE Large Program that carried out ESO Very (VLT) acquire,...
We present detailed model fits to observations of the disc around Herbig Ae star HD 163296. This well-studied object has an age ~ 4 Myr, with evidence a circumstellar extending out 540AU. use radiation thermo-chemical code ProDiMo gas and dust in 163296, attempt determine properties by fitting observational line continuum data. These include new Herschel/PACS obtained as part open-time key program GASPS (Gas Protoplanetary Systems), consisting detection [OI]63mic upper limits for several...
Planets are formed in disks around young stars. With an age of ~10 Myr, TW Hya is one the nearest T Tauri stars that still surrounded by a relatively massive disk. In addition large number molecules has been found disk, making perfect test case survey with <i>Herschel<i/>–PACS to directly study their gaseous component. We aim constrain gas and dust mass circumstellar disk Hya. observed fine-structure lines [O i] [C ii] as part open-time program GASPS. complement this continuum data...
Line spectra of 68 Taurus T Tauri stars were obtained with the Herschel-PACS (Photodetector Array Camera & Spectrometer) instrument as part GASPS (Gas Evolution in Protoplanetary Systems) survey protoplanetary discs. A careful examination line scans centred on [OI] 63.18 microns fine-structure unveiled a at 63.32 micron some these spectra. We identify this transition ortho-water. It is detected confidently (i.e., >3 sigma) eight sources, i.e., 24% sub-sample gas-rich Several statistical...
Context. The mass accretion rate (Ṁacc) is a key parameter that has not accurately been determined for wide sample of Herbig Ae/Be (HAeBe) stars until recently.
Herbig Ae/Be stars lie in the mass range between low and high young stars, therefore offer a unique opportunity to observe any changes formation processes that may occur across this boundary. This paper presents medium resolution VLT/X-Shooter spectra of six drawn from sample 91 targets, VLT/CRIRES five chosen based on presence CO first overtone bandhead emission their spectra. The X-Shooter survey reveals detection rate (7 per cent), consisting objects mainly spectral type B. A positive...
The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties Pre-Main Sequence(PMS) above low-mass range ($<2{\rm\thinspace M_{\odot}}$) and those bordering high-mass ($>8{\rm\thinspace M_{\odot}}$). This paper is second in a series exploring accretion 91 HAeBes with Very Large Telescope/X-shooter spectra. Equivalent width measurements are carried out on 32 different lines, spanning UV to NIR, order obtain their line luminosities. luminosities were compared luminosities, which...
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 analysed 337 multi-epoch optical spectra of 38 Herbig Ae/Be (HAeBe) stars to gain insights into the variability behaviour circumstellar (CS) atomic gas. Equivalent widths (EWs) and line fluxes Halpha, [OI]6300, HeI5876 NaID lines were obtained for each spectrum; Halpha width at 10% peak intensity (W10) profile shapes also measured classified. The mean strengths relative variabilities quantified star. Simultaneous photometry was used estimate fluxes. present a homogeneous spectroscopic...
HD 142527 is a young pre-main sequence star with properties indicative of the presence giant planet or/and low-mass stellar companion. We have analyzed an X-Shooter/Very Large Telescope spectrum to provide accurate parameters and accretion rate. The analysis spectrum, together constraints provided by SED fitting, distance (140 +- 20 pc) use evolutionary tracks isochrones, lead following set T_eff = 6550 100 K, log g 3.75 0.10, L_*/L_sun 16.3 4.5, M_*/M_sun 2.0 0.3 age 5.0 1.5 Myr. This...
Correlations between the accretion luminosity and emission line luminosities (Lacc Lline) of pre-main-sequence (PMS) stars have been published for many different spectral lines, which are used to estimate rates. Despite origin those correlations is unknown, this could be attributed direct or indirect physical relations formation mechanism. This work shows that all (near-UV/optical/near-IR) Lacc–Lline result fact stellar (L*) correlated, not necessarily related with line. Synthetic...
At the distance of 99-116 pc, HD141569A is one nearest HerbigAe stars that surrounded by a tenuous disk, probably in transition between massive primordial disk and debris disk. We observed fine-structure lines OI at 63 145 micron CII line 157 with PACS instrument onboard Herschel Space Telescope as part open-time large programme GASPS. complemented atomic observations archival Spitzer spectroscopic photometric continuum data, ground-based VLT-VISIR image 8.6 micron, 12CO fundamental...