Near infrared high resolution spectroscopy and spectro-astrometry of gas in disks around Herbig Ae/Be stars

AbstractHα high resolution spectroscopy combined with detailed numerical models is used to probe the physical conditions, such as density, temperature, and velocity of Be star disks. Models have been constructed for Be stars over a range in spectral types and inclination angles. We find that a variety of line shapes can be obtained by keeping the inclination fixed and changing density alone. This is due to the fact that our models account for disk temperature distributions self-consistently from the requirement of radiative equilibrium. A new analytical tool, called the variability ratio, was developed to identify emission-line stars at particular stages of variability. It is used in this work to quantify changes in the Hα equivalent widths for our observed spectra.

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Multi-Wavelength High-Resolution Spectroscopy for Exoplanet Detection: Motivation, Instrumentation and First Results

Geosciences ◽

10.3390/geosciences8080289 ◽

2018 ◽

Vol 8 (8) ◽

pp. 289 ◽

Cited By ~ 1

Author(s):

Serena Benatti

Keyword(s):

High Resolution ◽

Near Infrared ◽

Giant Planet ◽

High Resolution Spectroscopy ◽

M Dwarfs ◽

Low Mass Stars ◽

First Results ◽

Multi Wavelength ◽

Low Mass ◽

Rocky Planets

Exoplanet research has shown an incessant growth since the first claim of a hot giant planet around a solar-like star in the mid-1990s. Today, the new facilities are working to spot the first habitable rocky planets around low-mass stars as a forerunner for the detection of the long-awaited Sun-Earth analog system. All the achievements in this field would not have been possible without the constant development of the technology and of new methods to detect more and more challenging planets. After the consolidation of a top-level instrumentation for high-resolution spectroscopy in the visible wavelength range, a huge effort is now dedicated to reaching the same precision and accuracy in the near-infrared. Actually, observations in this range present several advantages in the search for exoplanets around M dwarfs, known to be the most favorable targets to detect possible habitable planets. They are also characterized by intense stellar activity, which hampers planet detection, but its impact on the radial velocity modulation is mitigated in the infrared. Simultaneous observations in the visible and near-infrared ranges appear to be an even more powerful technique since they provide combined and complementary information, also useful for many other exoplanetary science cases.

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On the synergy between Ariel and ground-based high-resolution spectroscopy

Experimental Astronomy ◽

10.1007/s10686-021-09824-7 ◽

2022 ◽

Author(s):

Gloria Guilluy ◽

Alessandro Sozzetti ◽

Paolo Giacobbe ◽

Aldo S. Bonomo ◽

Giuseppina Micela

Keyword(s):

High Resolution ◽

Near Infrared ◽

Major Axis ◽

High Resolution Spectroscopy ◽

Correlation Technique ◽

Temperature Structure ◽

Low Resolution ◽

Semi Major Axis ◽

Species Discovery ◽

Orbital Parameters

AbstractSince the first discovery of an extra-solar planet around a main-sequence star, in 1995, the number of detected exoplanets has increased enormously. Over the past two decades, observational instruments (both onboard and on ground-based facilities) have revealed an astonishing diversity in planetary physical features (i. e. mass and radius), and orbital parameters (e.g. period, semi-major axis, inclination). Exoplanetary atmospheres provide direct clues to understand the origin of these differences through their observable spectral imprints. In the near future, upcoming ground and space-based telescopes will shift the focus of exoplanetary science from an era of “species discovery” to one of “atmospheric characterization”. In this context, the Atmospheric Remote-sensing Infrared Exoplanet Large (Ariel) survey, will play a key role. As it is designed to observe and characterize a large and diverse sample of exoplanets, Ariel will provide constraints on a wide gamut of atmospheric properties allowing us to extract much more information than has been possible so far (e.g. insights into the planetary formation and evolution processes). The low resolution spectra obtained with Ariel will probe layers different from those observed by ground-based high resolution spectroscopy, therefore the synergy between these two techniques offers a unique opportunity to understanding the physics of planetary atmospheres. In this paper, we set the basis for building up a framework to effectively utilise, at near-infrared wavelengths, high-resolution datasets (analyzed via the cross-correlation technique) with spectral retrieval analyses based on Ariel low-resolution spectroscopy. We show preliminary results, using a benchmark object, namely HD 209458 b, addressing the possibility of providing improved constraints on the temperature structure and molecular/atomic abundances.

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Polarimetry and Physics of Be Star Envelopes (Review paper)

Symposium - International Astronomical Union ◽

10.1017/s0074180900037621 ◽

1982 ◽

Vol 98 ◽

pp. 77-93 ◽

Cited By ~ 1

Author(s):

George V. Coyne ◽

Ian S. McLean

Keyword(s):

High Resolution ◽

Near Infrared ◽

Theoretical Models ◽

Geometrical Parameters ◽

Be Stars ◽

Intermediate Band ◽

Wide Range ◽

Recent Developments ◽

Be Star ◽

Polarization Studies

A review of the most recent developments in polarization studies of Be stars is presented. New polarization techniques for high-resolution spectropolarimetry and for near infrared polarimetry are described and a wide range of new observations are discussed. These include broadband, intermediate-band and multichannel observations of the continuum polarization of Be stars in the wavelenght interval 0.3–2.2 microns, high resolution (0.5 Å) line profile polarimetry of a few stars and surveys of many stars for the purposes of statistical analyses. The physical significance of the observational material is discussed in the light of recent theoretical models. Emphasis is placed on the physical and geometrical parameters of Be star envelopes which polarimetry helps to determine.

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Be Phenomena in Young Early-type Stars: Various Forms of Interaction between the Star and the Circumstellar Gaseous Envelope

International Astronomical Union Colloquium ◽

10.1017/s0252921100056116 ◽

2000 ◽

Vol 175 ◽

pp. 344-347

Author(s):

M. Pogodin

Keyword(s):

High Resolution ◽

Stellar Wind ◽

Main Sequence ◽

Stellar Surface ◽

High Resolution Spectroscopy ◽

Evolutionary Status ◽

Be Stars ◽

Early Type ◽

Early Type Stars ◽

Gaseous Envelope

AbstractNew results of high-resolution spectroscopy of four pre-main sequence Ae/Be stars are presented. An analysis of parameters of lines originating in different regions of the circumstellar (CS) envelope (Hα, Hβ, He I 5876, DNal) allows to reconstruct a picture of the interaction between the star and the CS environment which can be displayed in different forms. At least two separate processes seem to impact the structural and kinematical properties of the envelope: the stellar wind from the stellar surface and the matter infall onto the star from the CS media. A possible relation between these two phenomena is discussed in the framework of different models. Some similarity between observational phenomena in Herbig Ae/Be and classical Be stars is noted in spite of their difference in evolutionary status.

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Results from six multiwavelength campaigns to study short-term FUV flux variability and phase-dependent mass loss in Be stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900215106 ◽

1994 ◽

Vol 162 ◽

pp. 284-286

Author(s):

Geraldine J. Peters

Keyword(s):

High Resolution ◽

Mass Loss ◽

High Resolution Spectroscopy ◽

Be Stars ◽

Short Term ◽

The Past ◽

Flux Variability ◽

Optical Region ◽

Dependent Mass

During the past six years we have carried through seven multiwavelength, multisite campaigns to investigate the cause for short-term (rapid) photometric and spectroscopic variability in Be stars and assess its importance in driving the mass loss in these objects. These campaigns usually included simultaneous observations in the UV with the IUE and Voyager spacecraft and optical region with ground-based telescopes worldwide (photometry, high resolution spectroscopy, and polarimetry). Typically 10–25 observers from 5–9 countries participated. Stars that have been observed include λ Eri, ω Ori, o And, ∊ Cap, 28 Cyg, η Cen, 48 Lib, ζ Tau, ψ Per, and 2 Vul. We briefly summarize some of the results from the UV study here. Additional results from the ground-based data are given in other papers in this volume by D. Gies, M. Hahula, J. Percy, and D. McDavid.

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Searching for H2 emission from protoplanetary disks using near- and mid-infrared high-resolution spectroscopy

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308016827 ◽

2007 ◽

Vol 3 (S249) ◽

pp. 359-368

Author(s):

A. Carmona ◽

M. E. van den Ancker ◽

Th. Henning ◽

Ya. Pavlyuchenkov ◽

C. P. Dullemond ◽

...

Keyword(s):

Surface Layer ◽

High Resolution ◽

Near Infrared ◽

Protoplanetary Disks ◽

High Resolution Spectroscopy ◽

Disk Model ◽

Mid Infrared ◽

T Tauri ◽

Hα Emission ◽

Ir Emission

AbstractThe mass and dynamics of protoplanetary disks are dominated by molecular hydrogen (H2). However, observationally very little is known about the H2. In this paper, we discuss two projects aimed to constrain the properties of H2 in the disk's planet forming region (R<50AU). First, we present a sensitive survey for pure-rotational H2 emission at 12.278 and 17.035 μm in a sample of nearby Herbig Ae/Be and T Tauri stars using VISIR, ESO's VLT high-resolution mid-infrared spectrograph. Second, we report on a search for H2 ro-vibrational emission at 2.1228, 2.2233 and 2.2477 μm in the classical T Tauri star LkHα 264 and the debris disk 49 Cet employing CRIRES, ESO's VLT high-resolution near-infrared spectrograph.VISIR project: none of the sources show H2 mid-IR emission. The observed disks contain less than a few tenths of MJupiter of optically thin H2 at 150 K, and less than a few MEarth at T>300 K. % and higher T. Our non-detections are consistent with the low flux levels expected from the small amount of H2 gas in the surface layer of a Chiang and Goldreich (1997) Herbig Ae two-layer disk model. In our sources the H2 and dust in the surface layer have not significantly departed from thermal coupling (Tgas/Tdust<2) and the gas-to-dust ratio in the surface layer is very likely <1000.CRIRES project: The H2 lines at 2.1218 μm and 2.2233 μm are detected in LkHα 264. An upper limit on the 2.2477 μm H2 line flux in LkHα 264 is derived. 49 Cet does not exhibit H2 emission in any of observed lines. There are a few MMoon of optically thin hot H2 in the inner disk (∼0.1 AU) of LkHα 264, and less than a tenth of a MMoon of hot H2 in the inner disk of 49 Cet. The shape of the 1–0 S(0) line indicates that LkHα disk is close to face-on (i<35o). The measured 1–0 S(0)/1–0 S(1) and 2–1 S(1)/1–0 S(1) line ratios in LkHα 264 indicate that the H2 is thermally excited at T<1500 K. The lack of H2 emission in the NIR spectra of 49 Cet and the absence of Hα emission suggest that the gas in the inner disk of 49 Cet has dissipated.

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