scholarly journals Mid-infrared Variability and Accretion in NGC 2264 Protostars

2015 ◽  
Vol 10 (S314) ◽  
pp. 209-210
Author(s):  
S. Terebey ◽  
A. M. Cody ◽  
L. M. Rebull ◽  
J. R. Stauffer
Keyword(s):  
Power Law ◽  
Function Analysis ◽  
Variable Mass ◽  
Young Star ◽  
T Tauri Stars ◽  
Light Curves ◽  
Class I ◽  
Mid Infrared ◽  
Infrared Wavelength ◽  
T Tauri

AbstractVariable mass accretion is thought to be an important aspect of protostar formation. Mid-infrared wavelength observations trace variations in accretion luminosity and thus can probe mass accretion on sub-AU scales. We present results from the Spitzer YSOVAR campaign towards Class I protostars in NGC 2264. The precise (0.02 mag) medium-cadence light curves at 3.6 and 4.5 microns show that young star variability is ubiquitous, with a variety of morphologies and time scales. A structure function analysis shows the light curves, on average, have a power-law behavior up to 30 days. The trend continues to longer timescales (years) for protostars (Class I), in contrast with the smaller brightness changes displayed by T Tauri stars (Class II). The power-law behavior suggests a stochastic process, such as turbulent mass accretion, drives the variability.

scholarly journals A mid-infrared interferometric survey of the planet-forming region around young Sun-like stars

2018 ◽  
Vol 14 (S345) ◽  
pp. 128-131
Author(s):  
József Varga ◽  
Péter Ábrahám ◽  
Lei Chen ◽  
Thorsten Ratzka ◽  
K. É. Gabányi ◽  
...  
Keyword(s):  
Spectral Feature ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Band Spectrum ◽  
Intermediate Mass ◽  
Mid Infrared ◽  
Disk Structure ◽  
T Tauri ◽  
General Difference ◽  
Herbig Ae Stars

AbstractWe present our results from a mid-infrared interferometric survey targeted at the planet-forming region in the circumstellar disks around low- and intermediate-mass young stars. Our sample consists of 82 objects, including T Tauri stars, Herbig Ae stars, and young eruptive stars. Our main results are: 1) Disks around T Tauri stars are similar to those around Herbig Ae stars, but are relatively more extended once we account for stellar luminosity. 2) From the distribution of the sizes of the mid-infrared emitting region we find that inner dusty disk holes may be present in roughly half of the sample. 3) Our analysis of the silicate spectral feature reveals that the dust in the inner ~1 au region of disks is generally more processed than that in the outer regions. 4) The dust in the disks of T Tauri stars typically show weaker silicate emission in the N band spectrum, compared to Herbig Ae stars, which may indicate a general difference in the disk structure. Our data products are available at VizieR, and at the following web page: http://konkoly.hu/MIDI_atlas.

scholarly journals Oh Observations Near the Reflection Nebulae Ngc 2068 and Ngc 2071

1974 ◽  
Vol 60 ◽  
pp. 301-302
Author(s):  
L. E. B. Johansson ◽  
B. Höglund ◽  
A. Winnberg ◽  
Nguyen-Q-Rieu ◽  
W. M. Goss
Keyword(s):  
Dust Cloud ◽  
T Tauri Stars ◽  
Emission Lines ◽  
Class I ◽  
Reflection Nebula ◽  
Cosmic Background ◽  
T Tauri ◽  
Reflection Nebulae

Narrow OH emission lines at 1667 MHz, apparently from a Class I source, have been observed near the reflection nebula NGC 2071. The region contains many T Tauri stars. OH emission corresponding to the dust cloud north and east of NGC 2024 is also seen. At 1720 MHz the dust cloud component appears in absorption; presumably the isotropic 2.7 K cosmic background is being absorbed.

scholarly journals Optical photometric variable stars towards Cygnus OB7

2019 ◽  
Vol 487 (2) ◽  
pp. 1765-1776 ◽  
Author(s):  
Somnath Dutta ◽  
Soumen Mondal ◽  
Santosh Joshi ◽  
Ramkrishna Das
Keyword(s):  
Variable Stars ◽  
T Tauri Stars ◽  
Light Curves ◽  
Main Sequence Stars ◽  
Star Forming ◽  
Rotation Rates ◽  
T Tauri ◽  
Photometric Observations ◽  
Sky Survey ◽  
Magnitude Diagram

ABSTRACT We present optical I-band light curves of the stars towards a star-forming region Cygnus OB7 from 17-night photometric observations. The light curves are generated from a total of 381 image frames with very good photometric precision. From the light curves of 1900 stars and their periodogram analyses, we detect 31 candidate variables including five previously identified. 14 out of 31 objects are periodic and exhibit the rotation rates in the range of 0.15–11.60 d. We characterize those candidate variables using optical/infrared colour–colour diagram and colour–magnitude diagram (CMD). From spectral indices of the candidate variables, it turns out that four are probably Classical T-Tauri stars (CTTSs), rest remain unclassified from present data, they are possibly field stars or discless pre-main-sequence stars towards the region. Based on their location on the various CMDs, the ages of two T Tauri Stars were estimated to be ∼5 Myr. The light curves indicate at least five of the periodic variables are eclipsing systems. The spatial distribution of young variable candidates on Planck 857 GHz (350 $\mu$m) and 2MASS (Two Micron All Sky Survey) Ks images suggest that at least two of the CTTSs are part of the active star-forming cloud Lynds 1003.

scholarly journals Properties of CVSO 30 from TESS measurements: probably a binary T Tauri star with complex light curves and no obvious planets

2020 ◽  
Vol 494 (3) ◽  
pp. 4349-4356
Author(s):  
C Koen
Keyword(s):  
Light Curve ◽  
Small Group ◽  
T Tauri Stars ◽  
Light Curves ◽  
Tauri Star ◽  
Curve Shape ◽  
T Tauri

ABSTRACT ‘Transiting Exoplanet Survey Satellite’ (TESS) photometry of CVSO 30 spanned 21.8 d, with a single large gap of 1.1 d. This allows alias-free determination of the two periodicities in the data. It is confirmed that both of these are non-sinusoidal: the dominant P1 = 0.4990 d has two detectable harmonics and P2 = 0.4486 d has seven. The large number of harmonics in the second periodicity characterizes a very complex light curve shape. One of the features in the light curve is a sharp dip of duration ∼2 h: this is probably the source of the previously claimed planetary transit signature. The star is a member of a small group of T Tauri stars with complex light curves, which have recently been exhaustively studied using Kepler and TESS observations. The two non-commensurate periods are most simply interpreted as being from two stars, i.e. CVSO 30 is probably a binary.

scholarly journals VLTI/MIDI atlas of disks around low- and intermediate-mass young stellar objects

2018 ◽  
Vol 617 ◽  
pp. A83 ◽  
Author(s):  
J. Varga ◽  
P. Ábrahám ◽  
L. Chen ◽  
Th. Ratzka ◽  
K. É. Gabányi ◽  
...  
Keyword(s):  
Spatial Information ◽  
Thermal Emission ◽  
T Tauri Stars ◽  
Young Stellar Objects ◽  
Intermediate Mass ◽  
Disk Model ◽  
Mid Infrared ◽  
Disk Structure ◽  
T Tauri ◽  
Silicate Feature

Context. Protoplanetary disks show large diversity regarding their morphology and dust composition. With mid-infrared interferometry the thermal emission of disks can be spatially resolved, and the distribution and properties of the dust within can be studied. Aims. Our aim is to perform a statistical analysis on a large sample of 82 disks around low- and intermediate-mass young stars, based on mid-infrared interferometric observations. We intend to study the distribution of disk sizes, variability, and the silicate dust mineralogy. Methods. Archival mid-infrared interferometric data from the MIDI instrument on the Very Large Telescope Interferometer are homogeneously reduced and calibrated. Geometric disk models are used to fit the observations to get spatial information about the disks. An automatic spectral decomposition pipeline is applied to analyze the shape of the silicate feature. Results. We present the resulting data products in the form of an atlas, containing N band correlated and total spectra, visibilities, and differential phases. The majority of our data can be well fitted with a continuous disk model, except for a few objects, where a gapped model gives a better match. From the mid-infrared size–luminosity relation we find that disks around T Tauri stars are generally colder and more extended with respect to the stellar luminosity than disks around Herbig Ae stars. We find that in the innermost part of the disks (r ≲ 1 au) the silicate feature is generally weaker than in the outer parts, suggesting that in the inner parts the dust is substantially more processed. We analyze stellar multiplicity and find that in two systems (AB Aur and HD 72106) data suggest a new companion or asymmetric inner disk structure. We make predictions for the observability of our objects with the upcoming Multi-AperTure mid-Infrared SpectroScopic Experiment (MATISSE) instrument, supporting the practical preparations of future MATISSE observations of T Tauri stars.

scholarly journals Investigating Disk Evolution: A High Spatial Resolution Mid‐Infrared Survey of T Tauri Stars

2006 ◽  
Vol 636 (2) ◽  
pp. 932-951 ◽  
Author(s):  
C. McCabe ◽  
A. M. Ghez ◽  
L. Prato ◽  
G. Duchene ◽  
R. S. Fisher ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
T Tauri Stars ◽  
Mid Infrared ◽  
T Tauri ◽  
Disk Evolution ◽  
Infrared Survey

scholarly journals Mid‐infrared Spectroscopy of Disks around Classical T Tauri Stars

2004 ◽  
Vol 154 (1) ◽  
pp. 443-447 ◽  
Author(s):  
W. J. Forrest ◽  
B. Sargent ◽  
E. Furlan ◽  
P. D’Alessio ◽  
N. Calvet ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
T Tauri Stars ◽  
Mid Infrared ◽  
Mid Infrared Spectroscopy ◽  
T Tauri

scholarly journals A Study of the Young Star V1331 CYG in a Compact Star-Forming Region

1998 ◽  
Vol 11 (1) ◽  
pp. 344-344
Author(s):  
Alisher Hojaev ◽  
Alexander Zheleznyak
Keyword(s):  
Compact Star ◽  
Young Star ◽  
Light Curves ◽  
Circumstellar Disk ◽  
Line Profiles ◽  
Periodic Process ◽  
Dark Cloud ◽  
Star Forming ◽  
T Tauri ◽  
Morphologic Analysis

The peculiar T Tauri type star V1331 Cyg = LkH 120, located in the dark cloud Lynds 984, is a FU Orionis pre-outburst candidate (McMuldroch et al., 1993). This star embedded in circumstellar bright nebulosity is also surrounded by a helix-shaped nebula originated from the star. We obtained a series of speckle images of V1331 Cyg on the standard VBR system on July 18-20, 1994 using the Zeiss 1000 1.0 m telescope of the High Altitude Maydanak Observatory in Uzbekistan. We also used the results of Johnson’s system photometry of V1331 Cyg, made simultaneously at Maydanak Observatory with a 0.6 m reflector. Images were computer processed. Surface photometry of the star and surrounding nebula was made and isophotes were constructed. Fourier analysis of light curves for V1331 Cyg has shown 36.2 day periodic process (Melnikov, priv. comm.) which could be due to the presence of a circumstellar disk. Morphologic analysis revealed a complex fine structure of nebula, consisting of many bright knots and obviously show a jet-like outflow. According to spectral observations (Chavarria K. 1981; Penston & Keavey 1977) the line profiles of V1331 Cyg are P Cyg type only; there are no detections of anti-P Cyg profiles during the last 25 years observations. This indicates a stable mass loss (on average, 10−7M⊙/yr) with mean velocities about −410 km/s.

scholarly journals The Carnegie Supernova Project II

2020 ◽  
Vol 639 ◽  
pp. A103 ◽  
Author(s):  
M. D. Stritzinger ◽  
F. Taddia ◽  
M. Fraser ◽  
T. M. Tauris ◽  
N. B. Suntzeff ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Electron Capture ◽  
Near Infrared ◽  
Companion Paper ◽  
Infrared Emission ◽  
Light Curves ◽  
Data Set ◽  
Mid Infrared ◽  
Space Telescope ◽  
Infrared Wavelength

We present multiwavelength observations of two gap transients that were followed by the Carnegie Supernova Project-II. The observations are supplemented with data obtained by a number of different programs. Here in the first of two papers, we focus on the intermediate-luminosity red transient (ILRT) designated SNhunt120, while in a companion paper we examine the luminous red novae AT 2014ej. Our data set for SNhunt120 consists of an early optical discovery, estimated to be within three days after outburst, the subsequent optical and near-infrared broadband followup extending over a period of about two months, two visual and two near-infrared wavelength spectra, and Spitzer Space Telescope observations extending from early (+28 d) to late (+1155 d) phases. SNhunt120 resembles other ILRTs such as NGC 300-2008-OT and SN 2008S, and like these other ILRTs, SNhunt120 exhibits prevalent mid-infrared emission at both early and late phases. From the comparison of SNhunt120 and other ILRTs to electron-capture supernova simulations, we find that the current models underestimate the explosion kinetic energy and thereby produce synthetic light curves that overestimate the luminosity. Finally, examination of pre-outburst Hubble Space Telescope images yields no progenitor detection.

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