scholarly journals Photometric and spectroscopic study of five pre-main sequence stars in the vicinity of NGC 7129

2019 ◽  
pp. 39-53
Author(s):  
E.H. Semkov ◽  
S.I. Ibryamov ◽  
S.P. Peneva
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
North West ◽  
T Tauri ◽  
Medium Resolution ◽  
Photometric Observations ◽  
All Optical ◽  
Ccd Observations ◽  
Photometric Monitoring

We present results from long-term optical photometric and spectroscopic observations of five pre-main sequence stars, located in the vicinity of the bright nebula NGC 7129. We obtained UBVRI photometric observations in the field centered on the star V391 Cep, north-west of the bright nebula NGC 7129. Our multicolor CCD observations spanned the period from February 1998 to November 2016. At the time of our photometric monitoring, a total of thirteen medium-resolution optical spectra of the stars were obtained. The results from our photometric study show that all stars exhibit strong variability in all optical passbands. Long-term light curves of the five stars indicate the typical classical T Tauri star variations in brightness with large amplitudes. We did not find any reliable periodicity in the brightness variations of all five stars. The results from spectral observations showed that all studied stars can be classified as classical T Tauri stars with rich emission line spectra and strong variability in profiles and intensity of emission lines.

scholarly journals Long-Term Multicolour Photometry of the Young Stellar Objects FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cygni

2015 ◽  
Vol 32 ◽  
Author(s):  
S. I. Ibryamov ◽  
E. H. Semkov ◽  
S. P. Peneva
Keyword(s):  
Gulf Of Mexico ◽  
Young Stellar Objects ◽  
Main Sequence Stars ◽  
Stellar Objects ◽  
Photometric Variability ◽  
The North ◽  
Dense Molecular Cloud ◽  
Photometric Observations ◽  
All Optical

AbstractResults from long-term multicolour optical photometric observations of the pre-main-sequence stars FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cyg collected during the period from 1997 June to 2014 December are presented. The objects are located in the dense molecular cloud L935, named ‘Gulf of Mexico’, in the field between the North America and Pelican nebulae. All stars from our study exhibit strong photometric variability in all optical passbands. Using our BVRI observations and data published by other authors, we tried to define the reasons for the observed brightness variations. The presented paper is a part of our long-term photometric study of the young stellar objects in the region of ‘Gulf of Mexico’.

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

2019 ◽  
Vol 627 ◽  
pp. A135 ◽  
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.

scholarly journals Photometric monitoring of pre-main sequence stars - I. The variability of RY and RU Lupi

1989 ◽  
Vol 237 (3) ◽  
pp. 683-694 ◽  
Author(s):  
M. G. Hutchinson ◽  
A. Evans ◽  
J. K. Davies ◽  
M. F. Bode
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Photometric Monitoring

scholarly journals Medium Resolution Spectroscopy at 1-2 Microns

1979 ◽  
Vol 47 ◽  
pp. 239-246
Author(s):  
J. R. Mould
Keyword(s):  
Fourier Transform ◽  
Main Sequence ◽  
Classification Criteria ◽  
Fourier Transform Spectrometer ◽  
Main Sequence Stars ◽  
Composite Spectra ◽  
Medium Resolution ◽  
M Stars

AbstractThe need for establishing classification criteria at long wavelengths is stressed. The usefulness of doing this is illustrated with a discussion of the composite spectra of FU Orionis stars. Spectra of these pre-main-sequence stars from 1.5-2.5μ were obtained with a Fourier Transform Spectrometer. Luminosity criteria in the l-2μ range are also discussed with application to M stars.

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.

IUE observations of pre-main-sequence stars. I - MG II and CA II resonance line fluxes for T Tauri stars

1981 ◽  
Vol 251 ◽  
pp. 113 ◽  
Author(s):  
M. S. Giampapa ◽  
N. Calvet ◽  
C. L. Imhoff ◽  
L. V. Kuhi
Keyword(s):  
Resonance Line ◽  
Main Sequence ◽  
T Tauri Stars ◽  
Main Sequence Stars ◽  
T Tauri

scholarly journals Long rotation period main-sequence stars from Kepler SAP light curves

2019 ◽  
Vol 489 (4) ◽  
pp. 5513-5529 ◽  
Author(s):  
Kaiming Cui ◽  
Jifeng Liu ◽  
Shuhong Yang ◽  
Qing Gao ◽  
Huiqin Yang ◽  
...  
Keyword(s):  
Light Curve ◽  
Main Sequence ◽  
Rotation Period ◽  
Light Curves ◽  
Stellar Rotation ◽  
Main Sequence Stars ◽  
Found Objects ◽  
Period Detection ◽  
Search Data

ABSTRACT Stellar rotation plays a key role in stellar activity. The rotation period could be detected through light curve variations caused by star-spots. Kepler provides two types of light curves: one is the Pre-search Data Conditioning (PDC) light curves, and the other is the Simple Aperture Photometer (SAP) light curves. Compared with the PDC light curves, the SAP light curves keep the long-term trend, relatively suitable for searches of long-period signals. However, SAP data are inflicted by some artefacts such as quarterly rolls and instrumental errors, making it difficult to find the physical periods in the SAP light curves. We explore a systematic approach based on the light curve pre-processing, period detection, and candidate selection. We also develop a simulated light curve test to estimate our detection limits for the SAP-like LCs. After applying our method to the raw SAP light curves, we found more than 1000 main-sequence stars with periods longer than 30 d; 165 are newly discovered. Considering the potential flaw of the SAP, we also inspect the newly found objects with photometry methods, and most of our periodical signals are confirmed.

scholarly journals Long-term photometric observations of pre-main sequence objects in the field of North America/Pelican Nebula

2014 ◽  
Vol 568 ◽  
pp. A49 ◽  
Author(s):  
I. Poljančić Beljan ◽  
R. Jurdana-Šepić ◽  
E. H. Semkov ◽  
S. Ibryamov ◽  
S. P. Peneva ◽  
...  
Keyword(s):  
North America ◽  
Main Sequence ◽  
Photometric Observations

scholarly journals A Rotational Period Study of a Large Sample of Pre-Main Sequence stars in NGC 2264

2004 ◽  
Vol 215 ◽  
pp. 125-126 ◽  
Author(s):  
M. Lamm ◽  
C.A.L. Bailer-Jones ◽  
R. Mundt ◽  
W. Herbst
Keyword(s):  
Main Sequence ◽  
Open Cluster ◽  
Monitoring Program ◽  
Bimodal Distribution ◽  
Main Sequence Stars ◽  
Lower Mass ◽  
Rotation Periods ◽  
Photometric Monitoring ◽  
Pms Stars ◽  
Mass Dependent

We present the results of a photometric monitoring program of pre-main sequence (PMS) stars in the young (2-4 Myr) open cluster NGC 2264 (d=700 pc). We find that the rotation periods are mass dependent and show a bimodal distribution for higher mass stars with M ≳ 0.3 M⊙ and a unimodal distribution for lower mass stars with M ≲ 0.3 M⊙.

scholarly journals Dynamics of wind and the dusty environments in the accreting T Tauri stars RY Tauri and SU Aurigae

2018 ◽  
Vol 483 (1) ◽  
pp. 132-146 ◽  
Author(s):  
P P Petrov ◽  
K N Grankin ◽  
J F Gameiro ◽  
S A Artemenko ◽  
E V Babina ◽  
...  
Keyword(s):  
T Tauri Stars ◽  
Gas Flows ◽  
Photometric Variability ◽  
Outflow Velocity ◽  
T Tauri ◽  
Photometric Observations ◽  
Accretion Model ◽  
Circumstellar Extinction ◽  
Magnetospheric Accretion

Abstract Classical T Tauri stars with ages of less than 10 Myr possess accretion discs. Magnetohydrodynamic processes at the boundary between the disc and the stellar magnetosphere control the accretion and ejections gas flows. We carried out a long series of simultaneous spectroscopic and photometric observations of the classical T Tauri stars, RY Tauri and SU Aurigae, with the aim to quantify the accretion and outflow dynamics at time-scales from days to years. It is shown that dust in the disc wind is the main source of photometric variability of these stars. In RY Tau, we observed a new effect: during events of enhanced outflow, the circumstellar extinction becomes lower. The characteristic time of changes in outflow velocity and stellar brightness indicates that the obscuring dust is near the star. The outflow activity in both stars is changing on a time-scale of years. Periods of quiescence in the variability of the Hα profile were observed during the 2015–2016 period in RY Tau and during the 2016–2017 period in SU Aur. We interpret these findings in the framework of the magnetospheric accretion model, and we discuss how the global stellar magnetic field can influence the long-term variations of the outflow activity.

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