A<i>Spitzer Space Telescope</i>Study of Disks in the Young σ Orionis Cluster

Hernández, Jesús; Hartmann, L.; Megeath, S. Thomas; Gutermuth, Robert; Muzerolle, James; Calvet, Nuria; Vivas, A. K.; Briceño, César; Allen, Lori; Stauffer, J. R.; Young, Erick T.; Fazio, G. G.

doi:10.1086/513735

Cited by 497 publications

(688 citation statements)

References 72 publications

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“…For the full PCM population in the ACIS FOV (Figure 6 Our Chandra observation of M17 SWex has identified a substantial population of very young IMPS with no IR excess. Clearly the inner disk lifetime for IMPS is shorter than the inner disk lifetime of~3 Myr for low-mass T Tauri stars, as numerous previous studies have reported (Hillenbrand et al 1992;Haisch et al 2001;Hernández et al 2007;Roccatagliata et al 2011). PW10 parameterized the disk lifetime t m d ( ) for IMPS in terms of a disk fraction with a power-law mass dependence,…”

Section: Total Stellar Populationmentioning

confidence: 99%

RAPID CIRCUMSTELLAR DISK EVOLUTION AND AN ACCELERATING STAR FORMATION RATE IN THE INFRARED DARK CLOUD M17 SWex

Povich

Townsley

Robitaille

et al. 2016

ApJ

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We present a catalog of 840 X-ray sources and first results from a 100 ks Chandra X-ray Observatory imaging study of the filamentary infrared (IR) dark cloud G014.225-00.506, which forms the central regions of a larger cloud complex known as the M17 southwest extension (M17 SWex). In addition to the rich population of protostars and young stellar objects with dusty circumstellar disks revealed by archival data from the Spitzer Space Telescope, we discover a population of X-ray-emitting, intermediate-mass pre-main-sequence stars that lack IR excess emission from circumstellar disks. We model the IR spectral energy distributions of this source population to measure its mass function and place new constraints on the destruction timescales for the inner dust disk for 2-8 M ☉ stars. We also place a lower limit on the star formation rate (SFR) and find that it is quite high (  M 0.007 M ☉ yr −1 ), equivalent to several Orion Nebula Clusters in G14.225-0.506 alone, and likely accelerating. The cloud complex has not produced a population of massive, O-type stars commensurate with its SFR. This absence of very massive (20 M ☉ ) stars suggests that either (1) M17 SWex is an example of a distributed mode of star formation that will produce a large OB association dominated by intermediate-mass stars but relatively few massive clusters, or (2) the massive cores are still in the process of accreting sufficient mass to form massive clusters hosting O stars.

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Section: Total Stellar Populationmentioning

confidence: 99%

RAPID CIRCUMSTELLAR DISK EVOLUTION AND AN ACCELERATING STAR FORMATION RATE IN THE INFRARED DARK CLOUD M17 SWex

Povich

Townsley

Robitaille

et al. 2016

ApJ

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“…For our new candidates (see Sect. 4), we have obtained the Spitzer photometry following the procedure described in Zapatero Osorio et al (2007) and using the data published by Hernández et al (2007) and Scholz & Jayawardhana (2008). A comparison of these two data sets is provided in Luhman et al (2008, see e.g.…”

Section: Near-and Mid-infrared Datamentioning

confidence: 99%

Candidate free-floating super-Jupiters in the young σ Orionis open cluster

Bihain

Rebolo

Osorio³

et al. 2009

A&A

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Context. Free-floating substellar candidates with estimated theoretical masses of as low as ∼5 Jupiter masses have been found in the ∼3 Myr old σ Orionis open cluster. As the overlap with the planetary mass domain increases, the question of how these objects form becomes important. The determination of their number density and whether a mass cut-off limit exists is crucial to understanding their formation. Aims. We propose to search for objects of yet lower masses in the cluster and determine the shape of the mass function at low mass. Methods. Using new-and (re-analysed) published IZJHK s [3.6]−[8.0]-band data of an area of 840 arcmin 2 , we performed a search for LT-type cluster member candidates in the magnitude range J = 19.5-21.5 mag, based on their expected magnitudes and colours. Results. Besides recovering the T type object S Ori 70 and two other known objects, we find three new cluster member candidates, S Ori 72-74, with J ≈ 21 mag and within 12 arcmin of the cluster centre. They have theoretical masses of 4 +3 −2 M Jup and are among the least massive free-floating objects detected by direct imaging outside the Solar System. The photometry in archival Spitzer [3.6]-[5.8]-band images infers that S Ori 72 is an L/T transition candidate and S Ori 73 a T-type candidate, following the expected cluster sequence in the mid-infrared. Finally, the L-type candidate S Ori 74 with lower quality photometry is located at 11.8 arcsec (∼4250 AU) of a stellar member of σ Orionis and could be a companion. After contaminant correction in the area complete to J = 21.1 mag, we estimate that there remain between zero and two cluster members in the mass interval 6-4 M Jup . Conclusions. We present S Ori 73, a new candidate T type and candidate σ Orionis member of a few Jupiter masses. Our result suggests a possible turnover in the substellar mass spectrum below ∼6 Jupiter masses, which could be investigated further by wider and deeper photometric surveys.

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“…For example, the bright (in the infrared) giant star IRAS 05358-0238 was once classified as a Class I object in the σ Orionis cluster (Oliveira & van Loon 2004;Hernández et al 2007;Caballero 2008). Since the surveyed area in this work is rich in star-forming regions (including σ Orionis), we had to be careful with disentangling both pre-main sequence and giant star populations.…”

Section: Variable Background Giantsmentioning

confidence: 99%

Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

2010

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We look for high-amplitude variable young stars in the open clusters and associations of the Orion Belt. We use public data from the ASAS-3 Photometric V -band Catalogue of the All Sky Automated Survey, infrared photometry from the 2MASS and IRAS catalogues, proper motions, and the Aladin sky atlas to obtain a list of the most variable stars in a survey area of side 5 deg centred on the bright star Alnilam (ǫ Ori) in the centre of the Orion Belt. We identify 32 highly-variable stars, of which 16 had not been reported to vary before. They are mostly variable young stars and candidates (16) and background giants (8), but there are also field cataclysmic variables, contact binaries, and eclipsing binary candidates. Of the young stars, which typically are active Herbig Ae/Be and T Tauri stars with Hα emission and infrared flux excess, we discover four new variables and confirm the variability status of another two. Some of them belong to the well known σ Orionis cluster. Besides, six of the eight giants are new variables, and three are new periodic variables.

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ASpitzer Space TelescopeStudy of Disks in the Young σ Orionis Cluster

Cited by 497 publications

References 72 publications

RAPID CIRCUMSTELLAR DISK EVOLUTION AND AN ACCELERATING STAR FORMATION RATE IN THE INFRARED DARK CLOUD M17 SWex

RAPID CIRCUMSTELLAR DISK EVOLUTION AND AN ACCELERATING STAR FORMATION RATE IN THE INFRARED DARK CLOUD M17 SWex

Candidate free-floating super-Jupiters in the young σ Orionis open cluster

Finding the most variable stars in the Orion Belt with the All Sky Automated Survey

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