scholarly journals What Can Observations of Young Binaries Tell Us about Binary Formation?

2001 ◽  
Vol 200 ◽  
pp. 346-360 ◽  
Author(s):  
Cathie J. Clarke
Keyword(s):  
Main Sequence ◽  
Binary Star ◽  
Spectral Energy ◽  
Strong Impact ◽  
Energy Distributions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Binary Formation ◽  
Future Task ◽  
Cloud Core

In this paper I discuss three areas in which observational data is likely to have a strong impact on theoretical ideas about binary star formation: the collation of binary statistics for different primary masses, the acquisition of spectral energy distributions for individual components within pre-main sequence binaries and the use of binary statistics to constrain the mix of star forming regions that must combine to form the field. Theoretical and observational work is ongoing in each of these areas. It is suggested that for observers an important future task is to remeasure the wide binary population among local field stars, whilst for theorists a problem yet to be addressed is how the mass of a molecular cloud core affects its binary fragmentation properties.

Star formation and polycyclic aromatic hydrocarbons in ELAIS N1 galaxies as seen by AKARI

2019 ◽  
Vol 71 (2) ◽  
Author(s):  
Tímea O Kovács ◽  
Denis Burgarella ◽  
Hidehiro Kaneda ◽  
Dániel Cs Molnár ◽  
Shinki Oyabu ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Star Formation ◽  
Aromatic Hydrocarbons ◽  
Main Sequence ◽  
Compact Star ◽  
Formation Rate ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Polycyclic Aromatic

Abstract We have examined the relationship between star formation and polycyclic aromatic hydrocarbons (PAHs) in a variety of galaxies. PAHs are excited by the ultraviolet photons of young stars, but they are disassociated by strong UV radiation in starbursts. Therefore their emission (which is in the wavelength range covered by AKARI) can be used as a star formation tracer in main sequence galaxies. We selected our targets in the ELAIS N1 field with AKARI detections, matched them with the Herschel Point Source Catalog, and collected other publicly available photometric data. Their spectral energy distributions (SEDs) were fitted, and several parameters of the galaxies were estimated, e.g., star formation rate (SFR), stellar mass, and the fraction of PAHs compared to dust mass (qPAH), and we examined the relationships between these parameters. The final sample consisted of 48 galaxies, with redshifts from 0.04 to 2.36. The estimated qPAH values were lower on average than typical values in the literature. This could be due to various reasons, such as low metallicity, or ongoing active galactic nucleus or starburst activity. Of our sample, 83% of the objects fell in the star-forming main sequence of galaxies, while only 8% could be considered as starbursts. We found a decreasing qPAH trend with increasing AV and consequently LIR, suggesting the possible presence of compact star-forming regions. We compared the qPAH values with the known relations of the PAH luminosities, but they did not always follow the same trends (SFR, LIR), and showed only slight correlation with the PAH luminosities.

scholarly journals Early science with the Large Millimetre Telescope: new mm-wave detections of circumstellar discs in IC 348 from LMT/AzTEC

2019 ◽  
Vol 488 (1) ◽  
pp. 1462-1480
Author(s):  
Michael S Petersen ◽  
Robert A Gutermuth ◽  
Erick Nagel ◽  
Grant W Wilson ◽  
James Lane
Keyword(s):  
Sensitive Indicator ◽  
High Mass ◽  
Spectral Energy ◽  
Complete Sample ◽  
Energy Distributions ◽  
Infrared Excess ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass ◽  
Stellar Properties

Abstract We present the most complete sample of mm measurements of protoplanetary discs in the star-forming region IC 348 to date. New observations from the Large Millimetre Telescope and the 1.1 mm camera AzTEC are combined with literature results in order to characterize the disc population as relating to both stellar properties within the IC 348 region and across other star-forming regions. In addition to detecting 28 of 116 observed known infrared-excess sources, we detected emission from two previously unknown candidate transition discs in the region. When combined with literature results, we find evidence for a steeper-than-expected slope, on average, in disc spectral energy distributions at millimetre wavelengths in the IC 348 region. We show that the presence or absence of high-mass discs is a sensitive indicator of regional evolution, both among star-forming regions and within IC 348. In contrast, low-mass discs exhibit almost no apparent evolution within the first ∼5 Myr when compared among regions.

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 Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample

2020 ◽  
Vol 494 (2) ◽  
pp. 2823-2838 ◽  
Author(s):  
Ana Trčka ◽  
Maarten Baes ◽  
Peter Camps ◽  
Sharon E Meidt ◽  
James Trayford ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Physical Properties ◽  
Numerical Models ◽  
Far Infrared ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Global Emission ◽  
Galaxy Sample ◽  
Galaxy Population

ABSTRACT We compare the spectral energy distributions (SEDs) and inferred physical properties for simulated and observed galaxies at low redshift. We exploit UV-submillimetre mock fluxes of ∼7000 z = 0 galaxies from the EAGLE suite of cosmological simulations, derived using the radiative transfer code skirt. We compare these to ∼800 observed galaxies in the UV-submillimetre range, from the DustPedia sample of nearby galaxies. To derive global properties, we apply the SED fitting code cigale consistently to both data sets, using the same set of ∼80 million models. The results of this comparison reveal overall agreement between the simulations and observations, both in the SEDs and in the derived physical properties, with a number of discrepancies. The optical and far-infrared regimes, and the scaling relations based upon the global emission, diffuse dust, and stellar mass, show high levels of agreement. However, the mid-infrared fluxes of the EAGLE galaxies are overestimated while the far-UV domain is not attenuated enough, compared to the observations. We attribute these discrepancies to a combination of galaxy population differences between the samples and limitations in the subgrid treatment of star-forming regions in the EAGLE-skirt post-processing recipe. Our findings show the importance of detailed radiative transfer calculations and consistent comparison, and provide suggestions for improved numerical models.

scholarly journals Infrared Spectral Energy Distributions ofz∼ 0.7 Star‐forming Galaxies

2007 ◽  
Vol 670 (1) ◽  
pp. 301-312 ◽  
Author(s):  
Xian Zhong Zheng ◽  
Herve Dole ◽  
Eric F. Bell ◽  
Emeric Le Floc’h ◽  
George H. Rieke ◽  
...  
Keyword(s):  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Star Forming ◽  
Infrared Spectral

scholarly journals Spectral energy distributions and structures of debris discs

2004 ◽  
Vol 202 ◽  
pp. 328-330
Author(s):  
W.R.F. Dent ◽  
M. C. Wyatt ◽  
W. S. Holland ◽  
J. S. Greaves ◽  
I. M. Coulson ◽  
...  
Keyword(s):  
Main Sequence ◽  
T Tauri Stars ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Long Wavelength ◽  
T Tauri

New photometry of main-sequence debris discs has been carried out at 850 and 450/μm; the derived SEDs indicate that the dust can lie in either thin rings or radially-extended discs, as seen directly in the few nearby objects which are resolvable. All such objects are consistent with a long wavelength opacity index β of 1.0±0.2 - similar to T Tauri stars, but significantly lower than embedded objects.

scholarly journals Using the CIFIST grid of CO5BOLD 3D model atmospheres to study the effects of stellar granulation on photometric colours

2018 ◽  
Vol 613 ◽  
pp. A24 ◽  
Author(s):  
A. Kučinskas ◽  
J. Klevas ◽  
H.-G. Ludwig ◽  
P. Bonifacio ◽  
M. Steffen ◽  
...  
Keyword(s):  
Main Sequence ◽  
Broad Band ◽  
Stellar Atmospheres ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Different Types ◽  
Convective Motions ◽  
Effective Temperatures ◽  
Red Giant ◽  
Colour Indices

Aims. We studied the influence of convection on the spectral energy distributions (SEDs), photometric magnitudes, and colour indices of different types of stars across the H–R diagram. Methods. The 3D hydrodynamical CO5BOLD, averaged ⟨3D⟩, and 1D hydrostatic LHD model atmospheres were used to compute SEDs of stars on the main sequence (MS), main sequence turn-off (TO), subgiant branch (SGB), and red giant branch (RGB), in each case at two different effective temperatures and two metallicities, [M∕H] = 0.0 and − 2.0. Using the obtained SEDs, we calculated photometric magnitudes and colour indices in the broad-band Johnson-Cousins UBVRI and 2MASS JHKs, and the medium-band Strömgren uvby photometric systems. Results. The 3D–1D differences in photometric magnitudes and colour indices are small in both photometric systems and typically do not exceed ± 0.03 mag. Only in the case of the coolest giants located on the upper RGB are the differences in the U and u bands able reach ≈−0.2 mag at [M∕H] = 0.0 and ≈−0.1 mag at [M∕H] = −2.0. Generally, the 3D–1D differences are largest in the blue-UV part of the spectrum and decrease towards longer wavelengths. They are also sensitive to the effective temperature and are significantly smaller in hotter stars. Metallicity also plays a role and leads to slightly larger 3D–1D differences at [M∕H] = 0.0. All these patterns are caused by a complex interplay between the radiation field, opacities, and horizontal temperature fluctuations that occur due to convective motions in stellar atmospheres. Although small, the 3D–1D differences in the magnitudes and colour indices are nevertheless comparable to or larger than typical photometric uncertainties and may therefore cause non-negligible systematic differences in the estimated effective temperatures.

scholarly journals Mon-735: a new low-mass pre-main-sequence eclipsing binary in NGC 2264

2020 ◽  
Vol 495 (2) ◽  
pp. 1531-1548
Author(s):  
Edward Gillen ◽  
Lynne A Hillenbrand ◽  
John Stauffer ◽  
Suzanne Aigrain ◽  
Luisa Rebull ◽  
...  
Keyword(s):  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Centre Of Mass ◽  
M Dwarfs ◽  
Eclipsing Binary ◽  
Star Forming ◽  
Low Mass ◽  
Effective Temperatures

ABSTRACT We present Mon-735, a detached double-lined eclipsing binary (EB) member of the ∼3 Myr old NGC 2264 star-forming region, detected by Spitzer. We simultaneously model the Spitzer light curves, follow-up Keck/HIRES radial velocities, and the system’s spectral energy distribution to determine self-consistent masses, radii, and effective temperatures for both stars. We find that Mon-735 comprises two pre-main-sequence M dwarfs with component masses of M = 0.2918 ± 0.0099 and 0.2661 ± 0.0095 M⊙, radii of R = 0.762 ± 0.022 and 0.748 ± 0.023 R⊙, and effective temperatures of Teff = 3260 ± 73 and 3213 ± 73 K. The two stars travel on circular orbits around their common centre of mass in P = 1.9751388 ± 0.0000050 d. We compare our results for Mon-735, along with another EB in NGC 2264 (CoRoT 223992193), to the predictions of five stellar evolution models. These suggest that the lower mass EB system Mon-735 is older than CoRoT 223992193 in the mass–radius diagram (MRD) and, to a lesser extent, in the Hertzsprung–Russell diagram (HRD). The MRD ages of Mon-735 and CoRoT 223992193 are ∼7–9 and 4–6 Myr, respectively, with the two components in each EB system possessing consistent ages.

scholarly journals Which attenuation curves for star-forming galaxies?

2019 ◽  
Vol 15 (S341) ◽  
pp. 70-73
Author(s):  
Véronique Buat ◽  
David Corre ◽  
Médéric Boquien ◽  
Katarzyna Małek
Keyword(s):  
Radiative Transfer ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Star Forming ◽  
Radiative Transfer Models ◽  
Attenuation Law ◽  
Dust Attenuation ◽  
Attenuation Laws ◽  
Transfer Models

AbstractDust attenuation shapes the spectral energy distributions of galaxies and any modelling and fitting procedure of their spectral energy distributions must account for this process. We present results of two recent works dedicated at measuring the dust attenuation curves in star forming galaxies at redshift from 0.5 to 3, by fitting continuum (photometric) and line (spectroscopic) measurements simultaneously with CIGALE using variable attenuation laws based on flexible recipes. Both studies conclude to a large variety of effective attenuation laws with an attenuation law flattening when the obscuration increases. An extra attenuation is found for nebular lines. The comparison with radiative transfer models implies a flattening of the attenuation law up to near infrared wavelengths, which is well reproduced with a power-laws recipe inspired by the Charlot and Fall recipe. Here we propose a global modification of the Calzetti attenuation law to better reproduce the results of radiative transfer models.

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