TITLE

Accurate determination of accretion and photospheric parameters in young stellar objects: The case of two candidate old disks in the Orion Nebula Cluster

AUTHOR(S)
Manara, C. F.; Beccari, G.; Da Rio, N.; De Marchi, G.; Natta, A.; Ricci, L.; Robberto, M.; Testi, L.
PUB. DATE
November 2013
SOURCE
Astronomy & Astrophysics / Astronomie et Astrophysique;Nov2013, Vol. 558, p1
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Context. Current planet formation models are largely based on the observational constraint that protoplanetary disks have a lifetime of ~3 Myr. Recent studies, however, report the existence of pre-main-sequence stars with signatures of accretion (strictly connected with the presence of circumstellar disks) and photometrically determined ages of 30 Myr or more. Aims. Here, we present a spectroscopic study of two major age outliers in the Orion Nebula Cluster. We use broadband, intermediate resolution VLT/X-shooter spectra combined with an accurate method to determine the stellar parameters and the related age of the targets to confirm their peculiar age estimates and the presence of ongoing accretion. Methods. The analysis is based on a multicomponent fitting technique, which derives simultaneously spectral type, extinction, and accretion properties of the objects. With this method, we confirm and quantify the ongoing accretion. From the photospheric parameters of the stars, we derive their position on the H-R diagram and the age given by evolutionary models. With other age indicators like the lithium-equivalent width, we estimate the age of the objects with high accuracy. Results. Our study shows that the two objects analyzed are not older than the typical population of the Orion Nebula Cluster. While photometric determination of the photospheric parameters are an accurate method to estimate the parameters of the bulk of young stellar populations, our results show that those of individual objects with high accretion rates and extinction may be affected by large uncertainties. Broadband spectroscopic determinations should thus be used to confirm the nature of individual objects. Conclusions. The analysis carried out shows that this method allows us to obtain an accurate determination of the photospheric parameters of accreting young stellar objects in any nearby star-forming region. We suggest that our detailed, broadband spectroscopy method should be used to derive accurate properties of candidate old and accreting young stellar objects in star-forming regions. We also discuss how a similarly accurate determination of stellar properties can be obtained through a combination of photometric and spectroscopic data.
ACCESSION #
91681777

 

Related Articles

  • Low-Mass Young Stars in Cep OB2: Ages, Distribution and Accretion Disks. Sicilia-Aguilar, Aurora; Hartmann, Lee; Brice&ño, César; Contreras, María Eugenia; Muzerolle, James; Calvet, Nuria // Astrophysics & Space Science;2004, Vol. 292 Issue 1-4, p457 

    We are studying the young clusters Tr37 and NGC7160 in the Cep OB2 region as part of a program to understand the evolution of accretion disks at the ages of disk dissipation and planet formation. Here, we present the first identifications of low mass (spectral types K-M) members of the clusters...

  • Multiple populations in globular clusters. Gratton, Raffaele; Carretta, Eugenio; Bragaglia, Angela // Astronomy & Astrophysics Review;Oct2012, Vol. 20 Issue 1, p1 

    Recent progress in studies of globular clusters has shown that they are not simple stellar populations, but rather are made up of multiple generations. Evidence stems both from photometry and spectroscopy. A new paradigm is arising for the formation of massive star clusters, which includes...

  • Spectroscopy of new brown dwarf members of ρ Ophiuchi and an updated initial mass function. de Oliveira, C. Alves; Moraux, E.; Bouvier, J.; Bouy, H. // Astronomy & Astrophysics / Astronomie et Astrophysique;Mar2012, Vol. 539, p1 

    Aims. To investigate the universality hypothesis of the initial mass function in the substellar regime, the population of the ρ Ophiuchi molecular cloud is analysed by including a new sample of low-mass spectroscopically confirmed members. To that end, we have conducted a large spectroscopic...

  • Spectral Analysis of AM CVn Systems. Krausz, D.; Nagel, T.; Rauch, T.; Werner, K. // AIP Conference Proceedings;11/30/2010, Vol. 1273 Issue 1, p305 

    AM CVn systems are hydrogen-deficient, short-period CVs. We describe the modeling of their spectra by means of NLTE accretion-disc models. For most of these objects, system parameters, like mass-accretion rate or primary mass, are not well known, resulting in an enormous time effort modeling...

  • Study of negative and positive superhumps in ER Ursae Majoris. Ohshima, Tomohito; Kato, Taichi; Pavlenko, Elena; Akazawa, Hidehiko; Imamura, Kazuyoshi; Tanabe, Kenji; de Miguel, Enrique; Stein, William; Itoh, Hiroshi; Hambsch, Franz-Josef; Dubovsky, Pavol A.; Kudzej, Igor; Krajci, Thomas; Baklanov, Alex; Samsonov, Denis; Antonyuk, Oksana I.; Malanushenko, Viktor; Andreev, Maksim V.; Noguchi, Ryo; Ogura, Kazuyuki // Publications of the Astronomical Society of Japan;Jul2014, Vol. 66 Issue 4, p1 

    We carried out photometric observations of the SU UMa-type dwarf nova ER UMa during 2011 and 2012, which showed the existence of persistent negative superhumps even during the superoutburst. We performed a two-dimensional period analysis of its light curves by using a method called “least...

  • Mining the UKIDSS Galactic Plane Survey: star formation and embedded clusters. Solin, O.; Ukkonen, E.; Haikala, L. // Astronomy & Astrophysics / Astronomie et Astrophysique;Jun2012, Vol. 542 Issue 1, p1 

    Context. Data mining techniques must be developed and applied to analyse the large public data bases containing hundreds to thousands of millions entries. Aims. We develop methods for locating previously unknown stellar clusters from the UKIDSS Galactic Plane Survey (GPS) catalogue data....

  • Multiple episodes of star formation in the CN15/16/17 molecular complex. Gennaro, M.; Bik, A.; Brandner, W.; Stolte, A.; Rochau, B.; Beuther, H.; Gouliermis, D.; Tackenberg, J.; Kudryavtseva, N.; Hussmann, B.; Schuller, F.; Henning, Th. // Astronomy & Astrophysics / Astronomie et Astrophysique;Jun2012, Vol. 542 Issue 2, pA74:1 

    Context. We have started a campaign to identify massive star clusters inside bright molecular bubbles towards the Galactic center. The CN15/16/17 molecular complex is the first example of our study. The region is characterized by the presence of two young clusters, DB10 and DB11, visible in the...

  • Star formation and environment in clusters up to z ∼ 2.2. Raichoor, A.; Andreon, S. // Astronomy & Astrophysics / Astronomie et Astrophysique;Jan2012, Vol. 537, p1 

    Context. The dependence of galaxy star-formation activity on environment - especially in clusters - at high redshift is still poorly understood, as illustrated by the still limited number of z ≳ 1.4 clusters on the one hand, and by the still debated star formation-density relation at high...

  • On the interpretation of sub-giant branch morphologies of intermediate-age star clusters with extended main sequence turnoffs. Goudfrooij, Paul; Girardi, Léo; Rosenfield, Philip; Bressan, Alessandro; Marigo, Paola; Correnti, Matteo; Puzia, Thomas H. // Monthly Notices of the Royal Astronomical Society;6/21/2015, Vol. 450 Issue 2, p1693 

    High-quality photometry of many star clusters in the Magellanic Clouds with ages of 1-2 Gyr revealed main sequence turnoffs (MSTOs) that are significantly wider than can be accounted for by a simple stellar population (SSP). Such extended MSTOs (eMSTOs) are often interpreted in terms of an age...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics