A Comparative Anatomy of Dusty Disks Imaged by NICMOS

Using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope we have conducted a coronagraphic imaging survey of 18 main sequence stars with large infrared excesses, searching for circumstellar dust (debris) in scattered light. Dusty disks with radial and hemispheric brightness anisotropies and complex morphologies, both possibly indicative of dynamical interactions with unseen planetary mass companions, were spatially resolved and imaged around three young (≲ 10Myr old) stars. From these observations we describe the debris systems around: a) HR 4796A (A0V), a 70 AU radius ring less than 14 AU wide with unequal ansal flux densities; b) HD 141569A (Herbig Ae/Be), a 400 AU radius disk with a 40 AU wide gap; and c) TW Hya (K7 T-Tauri), a pole-on circularly symmetric disk with a radial break in its surface density of scattering particles. Additionally, our non-detection of scattered light and high precision photometry of a fourth system of similar age, HD 98800 A/B, coupled with mid and thermal IR measurements, greatly constrain a likely model for the debris about the B component.

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A Detailed Study of the GG Tau Circumbinary Disk

Symposium - International Astronomical Union ◽

10.1017/s0074180900225278 ◽

2001 ◽

Vol 200 ◽

pp. 245-248

Author(s):

Caer-Eve McCabe ◽

Andrea M. Ghez

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Hubble Space Telescope ◽

Binary Star ◽

Infrared Images ◽

Space Telescope ◽

Spatially Resolved

We present near-infrared images of the circumbinary disk surrounding the pre–main-sequence binary star, GG Tau A, obtained with NICMOS aboard the Hubble Space Telescope. These images have a SNR ∼25 times higher than previous ground-based measurements, which allows the spatially resolved disk to be explored in detail. The geometry of the ring implies that the circumbinary disk is not intrinsically circular, possibly due to interactions with the central binary star. Overall, the circumbinary disk is redder than the central binary, with the amount of red excess increasing with wavelength. Significant variations in color over the 13 arcsec2 covered by the disk are also observed, raising the possibility that disk inhomogeneities are present.

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An Analysis of HST/FOS Spectra of Spatially Resolved Compact OB Systems in the LMC

Symposium - International Astronomical Union ◽

10.1017/s0074180900221323 ◽

2001 ◽

Vol 205 ◽

pp. 312-313

Author(s):

E. Niemczura ◽

H. Cugier

Keyword(s):

Main Sequence ◽

Hubble Space Telescope ◽

Large Magellanic Cloud ◽

Main Sequence Stars ◽

Space Telescope ◽

Multiple Systems ◽

Spatially Resolved ◽

Synthetic Spectra ◽

Faint Object ◽

Faint Object Spectrograph

An analysis of the spatially resolved (0.1) main-sequence stars of four compact multiple systems located in the Large Magellanic Cloud (LMC) is given. For this purpose we compared theoretical synthetic spectra with the observations obtained by means of the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope (HST).

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Red and Near Infrared Spectra* of Pre-Main Sequence Stars I. A Preliminary Investigation of T Tauri Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100069232 ◽

1977 ◽

Vol 42 ◽

pp. 100-105 ◽

Cited By ~ 1

Author(s):

Y. Andrillat

Keyword(s):

Color Index ◽

Main Sequence ◽

Near Infrared ◽

Preliminary Investigation ◽

Visible Spectrum ◽

T Tauri Stars ◽

Main Sequence Stars ◽

Type K ◽

T Tauri ◽

Near Infrared Spectra

230 Å mm-1 spectra of 30 stars of T Tauri or related type were obtained in the 8000-11000 Å region using a grating spectrograph equipped with an S-1 photocathode image-tube. In addition a few T Tauri stars were observed at the same dispersion in the 6200-8800 Å region on IN plate. A preliminary qualitative analysis of the observations leads to possible correlations between the intensities of emissions of the Ca II triplet, Paschen series and He I 10830 Å, and the spectral type, K-L color index of the star, or the [0 I] and Fe II intensities in the visible spectrum.

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Luminosity functions of YSO clusters in Sh-2 255, W3 Main and NGC 7538 star forming regions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002463 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 458-458

Author(s):

Devendra Ojha ◽

Motohide Tamura ◽

Keyword(s):

Main Sequence ◽

Near Infrared ◽

Infrared Camera ◽

Young Stellar Objects ◽

Main Sequence Stars ◽

Stellar Objects ◽

Star Forming ◽

Star Forming Regions ◽

Luminosity Functions ◽

Infrared Surveys

AbstractWe have conducted deep near-infrared surveys of the Sh-2 255, W3 Main and NGC 7538 massive star forming regions using simultaneous observations of the JHKs-band with the near-infrared camera SIRIUS on the UH 88-inch telescope and with SUBARU. The near-infrared surveys cover a total area of ~ 72 arcmin2 of three regions with 10-σ limiting magnitudes of ~ 19.5, 18.4 and 17.3 in J, H and Ks-band, respectively. Based on the color-color and color-magnitude diagrams and their clustering properties, the candidate young stellar objects are identified and their luminosity functions are constructed in Sh-2 255, W3 Main and NGC 7538 star forming regions. A large number of previously unreported red sources (H-K > 2) have also been detected around these regions. We argue that these red stars are most probably pre-main-sequence stars with intrinsic color excesses. The detected young stellar objects show a clear clustering pattern in each region: the Class I-like sources are mostly clustered in molecular cloud region, while the Class II-like sources are in or around more evolved optical HII regions. We find that the slopes of the Ks-band luminosity functions of Sh-2 255, W3 Main and NGC 7538 are lower than the typical values reported for the young embedded clusters, and their stellar populations are primarily composed of low mass pre-main-sequence stars. From the slopes of the Ks-band luminosity functions, we infer that Sh-2 255, W3 Main and NGC 7538 star forming regions are rather young (age ≤ 1 Myr).

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Near infrared camera and multi-object spectrometer for the Hubble Space Telescope

10.2514/6.1988-738 ◽

1988 ◽

Author(s):

RODGER THOMPSON

Keyword(s):

Near Infrared ◽

Hubble Space Telescope ◽

Infrared Camera ◽

Space Telescope

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Search for giant planets around seven white dwarfs in the Hyades cluster with the Hubble Space Telescope

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3422 ◽

2020 ◽

Vol 500 (3) ◽

pp. 3920-3925

Author(s):

Wolfgang Brandner ◽

Hans Zinnecker ◽

Taisiya Kopytova

Keyword(s):

White Dwarfs ◽

Near Infrared ◽

Hubble Space Telescope ◽

Infrared Camera ◽

Detection Limits ◽

Giant Planets ◽

High Angular Resolution ◽

Mass Detection ◽

Space Telescope ◽

Hyades Cluster

ABSTRACT Only a small number of exoplanets have been identified in stellar cluster environments. We initiated a high angular resolution direct imaging search using the Hubble Space Telescope (HST) and its Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument for self-luminous giant planets in orbit around seven white dwarfs in the 625 Myr old nearby (≈45 pc) Hyades cluster. The observations were obtained with Near-Infrared Camera 1 (NIC1) in the F110W and F160W filters, and encompass two HST roll angles to facilitate angular differential imaging. The difference images were searched for companion candidates, and radially averaged contrast curves were computed. Though we achieve the lowest mass detection limits yet for angular separations ≥0.5 arcsec, no planetary mass companion to any of the seven white dwarfs, whose initial main-sequence masses were >2.8 M⊙, was found. Comparison with evolutionary models yields detection limits of ≈5–7 Jupiter masses (MJup) according to one model, and between 9 and ≈12 MJup according to another model, at physical separations corresponding to initial semimajor axis of ≥5–8 au (i.e. before the mass-loss events associated with the red and asymptotic giant branch phase of the host star). The study provides further evidence that initially dense cluster environments, which included O- and B-type stars, might not be highly conducive to the formation of massive circumstellar discs, and their transformation into giant planets (with m ≥ 6 MJup and a ≥6 au). This is in agreement with radial velocity surveys for exoplanets around G- and K-type giants, which did not find any planets around stars more massive than ≈3 M⊙.

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Variability of young stellar objects in the star-forming region Pelican Nebula

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935418 ◽

2019 ◽

Vol 627 ◽

pp. A135 ◽

Cited By ~ 3

Author(s):

A. Bhardwaj ◽

N. Panwar ◽

G. J. Herczeg ◽

W. P. Chen ◽

H. P. Singh

Keyword(s):

Main Sequence ◽

T Tauri Stars ◽

Young Stellar Objects ◽

Spectral Energy ◽

Physical Parameters ◽

Main Sequence Stars ◽

Stellar Objects ◽

Star Forming ◽

T Tauri ◽

Optical Wavelengths

Context. Pre-main-sequence variability characteristics can be used to probe the physical processes leading to the formation and initial evolution of both stars and planets. Aims. The photometric variability of pre-main-sequence stars is studied at optical wavelengths to explore star–disk interactions, accretion, spots, and other physical mechanisms associated with young stellar objects. Methods. We observed a field of 16′ × 16′ in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012−2013. More than 250 epochs in the VRI bands are used to identify and classify variables up to V ∼ 21 mag. Their physical association with the cluster IC 5070 is established based on the parallaxes and proper motions from the Gaia second data release (DR2). Multiwavelength photometric data are used to estimate physical parameters based on the isochrone fitting and spectral energy distributions. Results. We present a catalog of optical time-series photometry with periods, mean magnitudes, and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (≥10 days) single or multiple fading and brightening events of up to two magnitudes at optical wavelengths. The typical mass and age of the pre-main-sequence variables from the isochrone fitting and spectral energy distributions are estimated to be ≤1 M⊙ and ∼2 Myr, respectively. We do not find any correlation between the optical amplitudes or periods with the physical parameters (mass and age) of pre-main-sequence stars. Conclusions. The low-mass pre-main-sequence stars in the Pelican Nebula region display distinct variability and color trends and nearly 30% of the variables exhibit strong periodic signatures attributed to cold spot modulations. In the case of accretion bursts and extinction events, the average amplitudes are larger than one magnitude at optical wavelengths. These optical magnitude fluctuations are stable on a timescale of one year.

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TESS Giants Transiting Giants. I.: A Noninflated Hot Jupiter Orbiting a Massive Subgiant

The Astronomical Journal ◽

10.3847/1538-3881/ac38a1 ◽

2022 ◽

Vol 163 (2) ◽

pp. 53

Author(s):

Nicholas Saunders ◽

Samuel K. Grunblatt ◽

Daniel Huber ◽

Karen A. Collins ◽

Eric L. N. Jensen ◽

...

Keyword(s):

Main Sequence ◽

Planetary System ◽

Scattered Light ◽

Image Data ◽

Velocity Measurements ◽

Main Sequence Stars ◽

Transiting Planets ◽

Depth Difference ◽

Evolved Stars ◽

Hot Jupiter

Abstract While the population of confirmed exoplanets continues to grow, the sample of confirmed transiting planets around evolved stars is still limited. We present the discovery and confirmation of a hot Jupiter orbiting TOI-2184 (TIC 176956893), a massive evolved subgiant (M ⋆ = 1.53 ± 0.12 M ⊙, R ⋆ = 2.90 ± 0.14 R ⊙) in the Transiting Exoplanet Survey Satellite (TESS) Southern Continuous Viewing Zone. The planet was flagged as a false positive by the TESS Quick-Look Pipeline due to periodic systematics introducing a spurious depth difference between even and odd transits. Using a new pipeline to remove background scattered light in TESS Full Frame Image data, we combine space-based TESS photometry, ground-based photometry, and ground-based radial velocity measurements to report a planet radius of R p = 1.017 ± 0.051 R J and mass of M p = 0.65 ± 0.16 M J . For a planet so close to its star, the mass and radius of TOI-2184b are unusually well matched to those of Jupiter. We find that the radius of TOI-2184b is smaller than theoretically predicted based on its mass and incident flux, providing a valuable new constraint on the timescale of post-main-sequence planet inflation. The discovery of TOI-2184b demonstrates the feasibility of detecting planets around faint (TESS magnitude > 12) post-main-sequence stars and suggests that many more similar systems are waiting to be detected in the TESS FFIs, whose confirmation may elucidate the final stages of planetary system evolution.

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