scholarly journals TIC 278825952: a triply eclipsing hierarchical triple system with the most intrinsically circular outer orbit

2020 ◽  
Vol 498 (4) ◽  
pp. 6034-6043
Author(s):  
T Mitnyan ◽  
T Borkovits ◽  
S A Rappaport ◽  
A Pál ◽  
P F L Maxted
Keyword(s):  
Massive Star ◽  
Spectral Energy Distribution ◽  
Time Effect ◽  
Photometric Data ◽  
Spectral Energy ◽  
Star System ◽  
Third Body ◽  
The Third ◽  
Mutual Inclination ◽  
Triple Star

ABSTRACT We report the discovery of a compact triply eclipsing triple star system in the southern continuous viewing zone of the TESS space telescope. TIC 278825952 is a previously known, but unstudied circular eclipsing binary with a period of 4.781 d with a tertiary component in a wider, circular orbit of 235.55-d period that was found from three sets of third-body eclipses and from light travel-time effect dominated eclipse timing variations. We performed a joint photodynamical analysis of the eclipse timing variation curves, photometric data, and the spectral energy distribution, coupled with the use of PARSEC stellar isochrones. We find that the inner binary consists of slightly evolved, near twin stars of masses of 1.12 and 1.09 M⊙ and radii of 1.40 and 1.31 R⊙. The third, less massive star has a mass of 0.75 M⊙ and radius of 0.70 R⊙. The low mutual inclination and eccentricities of the orbits show that the system is highly coplanar and surprisingly circular.

scholarly journals The compact triply eclipsing triple star TIC 209409435 discovered with TESS

2020 ◽  
Vol 496 (4) ◽  
pp. 4624-4636 ◽  
Author(s):  
T Borkovits ◽  
S A Rappaport ◽  
T G Tan ◽  
R Gagliano ◽  
T Jacobs ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Distribution Data ◽  
Third Body ◽  
Multiple Star ◽  
The Third ◽  
Inclination Angles ◽  
Mutual Inclination ◽  
Triple Star

ABSTRACT We report the discovery in TESS Sectors 3 and 4 of a compact triply eclipsing triple star system. TIC 209409435 is a previously unknown eclipsing binary with a period of 5.717 d, and the presence of a third star in an outer eccentric orbit of 121.872-d period was found from two sets of third-body eclipses and from eclipse timing variations. The latter exhibits signatures of strong third-body perturbations. After the discovery, we obtained follow-up ground-based photometric observations of several binary eclipses as well as another of the third-body eclipses. We carried out comprehensive analyses, including the simultaneous photodynamical modelling of TESS and ground-based light curves (including both archival WASP data, and our own follow-up measurements), as well as eclipse timing variation curves. Also, we have included in the simultaneous fits multiple star spectral energy distribution data and theoretical PARSEC stellar isochrones. We find that the inner binary consists of near twin stars of mass 0.90 M⊙ and radius 0.88 R⊙. The third star is just 9 per cent more massive and 18 per cent larger in radius. The inner binary has a rather small eccentricity, while the outer orbit has e = 0.40. The inner binary and outer orbit have inclination angles within 0.1° and 0.2° of 90°, respectively. The mutual inclination angle is ≲1/4°. All of these results were obtained without radial velocity observations.

scholarly journals Light-time effect detected in fourteen eclipsing binaries

2020 ◽  
Vol 643 ◽  
pp. A130
Author(s):  
P. Zasche ◽  
R. Uhlař ◽  
P. Svoboda ◽  
P. Cagaš ◽  
M. Mašek
Keyword(s):  
Time Effect ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Physical Parameters ◽  
Third Body ◽  
Light Curve Analysis ◽  
Multiple Systems ◽  
The Third ◽  
Minimal Mass ◽  
Triple Star

The available minima timings of 14 selected eclipsing binaries (V1297 Cas, HD 24105, KU Aur, GU CMa, GH Mon, AZ Vel, DI Lyn, DK Her, GQ Dra, V624 Her, V1134 Her, KIC 6187893, V1928 Aql, V2486 Cyg) were collected and analyzed. Using the automatic telescopes, surveys, and satellite data, we derived more than 2500 times of eclipses, accompanied with our own ground-based observations. These data were used to detect the period variations in these multiple systems. The eclipse timing variations were described using the third-body hypothesis and the light-time effect. Their respective periods were derived as 2.5, 16.2, 27, 20, 64, 5.6, 22, 115, 27, 42, 6.9, 11.2, 4.1, and 8.4 years for these systems, respectively. The predicted minimal mass of the third body was calculated for each of the systems, and we discuss here their prospective detectability. The light curves of HD 24105, GH Mon, DK Her, V1134 Her, KIC 6187893, V1928 Aql, and V2486 Cyg were analyzed using the PHOEBE program, resulting in physical parameters of the components. Significant fractions of the third light were detected during the light-curve analysis, supporting our hypothesis of the triple-star nature of all these systems. The majority of these systems (nine out of 14) were already known as visual doubles. Our study shifts them to possible quadruples, what makes them even more interesting.

scholarly journals Sporadic and intense accretion in a 1 Myr-old brown dwarf candidate

2020 ◽  
Vol 634 ◽  
pp. A128
Author(s):  
D. Nguyen-Thanh ◽  
N. Phan-Bao ◽  
S. J. Murphy ◽  
M. S. Bessell
Keyword(s):  
Spectral Energy Distribution ◽  
Brown Dwarfs ◽  
Photometric Data ◽  
Spectral Energy ◽  
Brown Dwarf ◽  
M Dwarfs ◽  
Trigonometric Parallax ◽  
Accretion Process ◽  
Accretion Rates ◽  
Low Mass

Context. Studying the accretion process in very low-mass objects has important implications for understanding their formation mechanism. Many nearby late-M dwarfs that have previously been identified in the field are in fact young brown dwarf members of nearby young associations. Some of them are still accreting. They are therefore excellent targets for further studies of the accretion process in the very low-mass regime at different stages. Aims. We aim to search for accreting young brown dwarf candidates in a sample of 85 nearby late-M dwarfs. Methods. Using photometric data from DENIS, 2MASS, and WISE, we constructed the spectral energy distribution of the late- M dwarfs based on BT-Settl models to detect infrared excesses. We then searched for lithium and Hα emission in candidates that exhibit infrared excesses to confirm their youth and the presence of accretion. Results. Among the 85 late-M dwarfs, only DENIS-P J1538317−103850 (M5.5) shows strong infrared excesses in WISE bands. The detection of lithium absorption in the M5.5 dwarf and its Gaia trigonometric parallax indicate an age of ~1 Myr and a mass of 47 MJ. The Hα emission line in the brown dwarf shows significant variability that indicates sporadic accretion. This 1 Myr-old brown dwarf also exhibits intense accretion bursts with accretion rates of up to 10−7.9 M⊙ yr−1. Conclusions. Our detection of sporadic accretion in one of the youngest brown dwarfs might imply that sporadic accretion at early stages could play an important role in the formation of brown dwarfs. Very low-mass cores would not be able to accrete enough material to become stars, and thus they end up as brown dwarfs.

scholarly journals Timing the earliest quenching events with a robust sample of massive quiescent galaxies at 2 < z < 5

2020 ◽  
Vol 496 (1) ◽  
pp. 695-707 ◽  
Author(s):  
A C Carnall ◽  
S Walker ◽  
R J McLure ◽  
J S Dunlop ◽  
D J McLeod ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Selection Criteria ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Star Forming ◽  
Photometric Redshift ◽  
The Times ◽  
Lower Redshift

ABSTRACT We present a sample of 151 massive (M* &gt; 1010 M⊙) quiescent galaxies at 2 &lt; z &lt; 5, based on a sophisticated Bayesian spectral energy distribution fitting analysis of the CANDELS UDS and GOODS-South fields. Our sample includes a robust sub-sample of 61 objects for which we confidently exclude low-redshift and star-forming solutions. We identify 10 robust objects at z &gt; 3, of which 2 are at z &gt; 4. We report formation redshifts, demonstrating that the oldest objects formed at z &gt; 6; however, individual ages from our photometric data have significant uncertainties, typically ∼0.5 Gyr. We demonstrate that the UVJ colours of the quiescent population evolve with redshift at z &gt; 3, becoming bluer and more similar to post-starburst galaxies at lower redshift. Based upon this, we construct a model for the time evolution of quiescent galaxy UVJ colours, concluding that the oldest objects are consistent with forming the bulk of their stellar mass at z ∼ 6–7 and quenching at z ∼ 5. We report spectroscopic redshifts for two of our objects at z = 3.440 and 3.396, which exhibit extremely weak Ly α emission in ultra-deep VANDELS spectra. We calculate star formation rates based on these line fluxes, finding that these galaxies are consistent with our quiescent selection criteria, provided their Ly α escape fractions are &gt;3 and &gt;10 per cent, respectively. We finally report that our highest redshift robust object exhibits a continuum break at λ ∼ 7000 Å in a spectrum from VUDS, consistent with our photometric redshift of $z_\mathrm{phot}=4.72^{+0.06}_{-0.04}$. If confirmed as quiescent, this object would be the highest redshift known quiescent galaxy. To obtain stronger constraints on the times of the earliest quenching events, high-SNR spectroscopy must be extended to z ≳ 3 quiescent objects.

scholarly journals The stellar metallicity distribution in intermediate-latitude fields

2012 ◽  
Vol 8 (S295) ◽  
pp. 319-319
Author(s):  
Xiyan Peng ◽  
Cuihua Du ◽  
Zhenyu Wu
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Photometric Data ◽  
Spectral Energy ◽  
Galactic Centre ◽  
Fitting Method ◽  
The Galaxy ◽  
The Mean ◽  
Metallicity Distribution

AbstractBased on BATC and SDSS photometric data, we adopt the spectral energy distribution (SED) fitting method to evaluate stellar metallicities in the Galaxy. We find that the mean metallicity shifts from metal-rich to metal-poor with the increase of distance from the Galactic Centre.

scholarly journals The Spectral Energy Distribution of the Earliest Phases of Massive Star Formation

2015 ◽  
Vol 12 (S316) ◽  
pp. 151-152
Author(s):  
Randolf Klein ◽  
Jennifer Cooper ◽  
Leslie Looney ◽  
Thomas Henning ◽  
Sukanya Chakrabarti ◽  
...  
Keyword(s):  
Star Formation ◽  
Energy Distribution ◽  
Massive Star ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Status Report ◽  
Massive Star Formation ◽  
Data Set ◽  
Good Spatial Resolution ◽  
Early Phases

AbstractWe have selected cold and massive (M > 100M⊙) cores as candidates for early phases of star formation from millimeter continuum surveys without associations at short wavelengths. We compared the millimeter continuum peak positions with IR and radio catalogs and excluded cores that had sources associated with the cores’ peaks. We compiled a list of 173 cores in over 117 regions that are candidates for very early phases of Massive Star Formation (MSF). Now with the Spitzer and Herschel archives, these cores can be characterized further. We are compiling this data set to construct the complete spectral energy distribution (SED) in the mid- and far-infrared with good spatial resolution and broad spectral coverage. This allow us to disentangle the complex regions and model the SED of the deeply embedded protostars/clusters. We present a status report of our efforts: a preview of the IR properties of all cores and their embedded source inferred from a grey body fit to the compiled SEDs.

scholarly journals Massive star cluster formation and evolution in tidal dwarf galaxies

2019 ◽  
Vol 628 ◽  
pp. A60 ◽  
Author(s):  
Jérémy Fensch ◽  
Pierre-Alain Duc ◽  
Médéric Boquien ◽  
Debra M. Elmegreen ◽  
Bruce G. Elmegreen ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Massive Star ◽  
Dwarf Galaxies ◽  
Cluster Formation ◽  
Spectral Energy Distribution ◽  
Star Clusters ◽  
Star Cluster ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Near Ultraviolet

Context. The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation. Aims. We study star cluster formation in a tidal debris, including the vicinity of three tidal dwarf galaxies, in a massive gas-dominated collisional ring around NGC 5291. These dwarfs have physical parameters that differ significantly from local starbursting dwarfs. They are gas rich, highly turbulent, their gas metallicity is already enriched up to half solar values, and they are expected to be free of dark matter. The aim is to study massive star cluster formation in this as yet unexplored type of environment. Methods. We used imaging from the Hubble Space Telescope using broadband filters that cover the wavelength range from the near-ultraviolet to the near-infrared. We determined the masses and ages of the cluster candidates by using the spectral energy distribution-fitting code CIGALE. We considered age-extinction degeneracy effects on the estimation of the physical parameters. Results. We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of ∼40%, which is similar to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they were formed at the very birth of the tidal dwarf galaxies. These clusters have survived for several hundred million years. Therefore our study shows that extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the young star clusters are not massive enough to survive for a Hubble time. However, it may be speculated that similar objects at higher redshift, with a higher star formation rate, might form some of the long-lived globular clusters.

scholarly journals Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud

2020 ◽  
Vol 498 (3) ◽  
pp. 3283-3301 ◽  
Author(s):  
Giada Pastorelli ◽  
Paola Marigo ◽  
Léo Girardi ◽  
Bernhard Aringer ◽  
Yang Chen ◽  
...  
Keyword(s):  
Mass Loss Rate ◽  
Spectral Energy Distribution ◽  
Stellar Populations ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Asymptotic Giant Branch ◽  
Star Formation History ◽  
Spectral Energy ◽  
Agb Stars ◽  
The Third

ABSTRACT Reliable models of the thermally pulsing asymptotic giant branch (TP-AGB) phase are of critical importance across astrophysics, including our interpretation of the spectral energy distribution of galaxies, cosmic dust production, and enrichment of the interstellar medium. With the aim of improving sets of stellar isochrones that include a detailed description of the TP-AGB phase, we extend our recent calibration of the AGB population in the Small Magellanic Cloud (SMC) to the more metal-rich Large Magellanic Cloud (LMC). We model the LMC stellar populations with the trilegal code, using the spatially resolved star formation history derived from the VISTA survey. We characterize the efficiency of the third dredge-up by matching the star counts and the Ks-band luminosity functions of the AGB stars identified in the LMC. In line with previous findings, we confirm that, compared to the SMC, the third dredge-up in AGB stars of the LMC is somewhat less efficient, as a consequence of the higher metallicity. The predicted range of initial mass of C-rich stars is between Mi ≈ 1.7 and 3 M⊙ at Zi = 0.008. We show how the inclusion of new opacity data in the carbon star spectra will improve the performance of our models. We discuss the predicted lifetimes, integrated luminosities, and mass-loss rate distributions of the calibrated models. The results of our calibration are included in updated stellar isochrones publicly available.

scholarly journals Searches for pulsar-like candidates from unidentified objects in the Third Catalog of Hard Fermi-LAT Sources with machine learning techniques

2020 ◽  
Vol 495 (1) ◽  
pp. 1093-1109 ◽  
Author(s):  
C Y Hui ◽  
Jongsu Lee ◽  
K L Li ◽  
Sangin Kim ◽  
Kwangmin Oh ◽  
...  
Keyword(s):  
Machine Learning ◽  
Globular Clusters ◽  
Classification Scheme ◽  
Spectral Energy Distribution ◽  
Machine Learning Techniques ◽  
Spectral Energy ◽  
Periodic Signal ◽  
X Ray ◽  
The Third ◽  
Γ Ray

ABSTRACT We report the results of searching pulsar-like candidates from the unidentified objects in the Third Catalog of Hard Fermi-LAT Sources (3FHL). Using a machine-learning-based classification scheme with a nominal accuracy of $\sim \!98{{\, \rm per\, cent}}$, we have selected 27 pulsar-like objects from 200 unidentified 3FHL sources for an identification campaign. Using archival data, X-ray sources are found within the γ-ray error ellipses of 10 3FHL pulsar-like candidates. Within the error circles of the much better constrained X-ray positions, we have also searched for the optical/infrared counterparts and examined their spectral energy distributions. Among our shortlisted candidates, the most secure identification is the association of 3FHL J1823.3–1339 and its X-ray counterpart with the globular cluster Mercer 5. The γ-rays from the source can be contributed by a population of millisecond pulsars residing in the cluster. This makes Mercer 5 as one of the slowly growing hard γ-ray population of globular clusters with emission &gt;10 GeV. Very recently, another candidate picked by our classification scheme, 3FHL J1405.1–6118, has been identified as a new γ-ray binary with an orbital period of 13.7 d. Our X-ray analysis with a short Chandra observation has found a possible periodic signal candidate of ∼1.4 h and a putative extended X-ray tail of ∼20 arcsec long. Spectral energy distribution of its optical/infrared counterpart conforms with a blackbody of Tbb ∼ 40 000 K and Rbb ∼ 12 R⊙ at a distance of 7.7 kpc. This is consistent with its identification as an early O star as found by infrared spectroscopy.

scholarly journals The molecular cloud and embedded young stellar population associated with IRAS 18236–1205

2009 ◽  
Vol 5 (S266) ◽  
pp. 516-516
Author(s):  
Ricardo Retes ◽  
Abraham Luna ◽  
Divakara Mayya ◽  
Luis Carrasco
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Massive Star ◽  
Stellar Population ◽  
Spectral Energy Distribution ◽  
Point Sources ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Massive Star Formation ◽  
Iras Source

AbstractWe test a membership method to select embedded young stellar objects (YSOs) from a Galactic molecular cloud with ongoing massive star formation using multiband analysis. We select and discuss the embedded stellar population in the molecular cloud associated with IRAS 18235−1205, a small, geometrically well-defined Galactic molecular cloud. The IRAS source has infrared fluxes characteristic of an UCHii region, CS(J = 2 − 1) emission, and methanol and water maser emission, suggesting that this region is a good candidate for studies of young, massive star formation. The selection method of embedded stellar populations is based on the spatial distribution of 13CO(J = 1 − 0) and Spitzer/MIPS 24 μm point sources. Photometric analysis using near/mid-infrared images are used to test our selection criteria. Three objects are associated with the IRAS source; two have a characteristic spectral-energy distribution (SED) of a Class I/0 object (protostar) and the third has an SED of Class II.

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