ROSAT X-Ray Study of the Chamaeleon I Dark Cloud. I. The Stellar Population

Feigelson, E. D.; Casanova, S.; Montmerle, T.; Guibert, J.

doi:10.1086/173264

Cited by 146 publications

(173 citation statements)

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“…In particular, a useful correlation is found between the intrinsic X-ray luminosity of the sources and their optical and near-IR magnitudes. This correlation was similar to the one found previously by Feigelson et al (1993) and Casanova et al (1995) from ROSAT studies of the nearby Chamaeleon I and ρ Ophiuchi clouds, respectively, suggesting a general validity which we will use in the present paper. The main interest in this correlation is that it is weakly dependent on extinction, which is essential for the study of young stars, because of the comparable absorption cross-sections in the near-IR and keV ranges (Ryter 1996).…”

Section: Search For Young Stars Based On X-ray Datasupporting

confidence: 90%

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Star formation history of Canis Major R1

Gregorio-Hetem¹,

Montmerle

Rodrigues

et al. 2009

A&A

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Aims. The CMa R1 star-forming region contains several compact clusters as well as many young early-B stars. It is associated with a well-known bright rimmed nebula, the nature of which is unclear (fossil HII region or supernova remnant). To help elucidate the nature of the nebula, our goal was to reconstruct the star-formation history of the CMa R1 region, including the previously unknown older, fainter low-mass stellar population, using X-rays. Methods. We analyzed images obtained with the ROSAT satellite, covering ∼5 sq. deg. Complementary VRI photometry was performed with the Gemini South telescope. Colour-magnitude and colour-colour diagrams were used in conjunction with pre-main sequence evolutionary tracks to derive the masses and ages of the X-ray sources.Results. The ROSAT images show two distinct clusters. One is associated with the known optical clusters near Z CMa, to which ∼40 members are added. The other, which we name the "GU CMa" cluster, is new, and contains ∼60 members. The ROSAT sources are young stars with masses down to M ∼ 0.5 M , and ages up to 10 Myr. The mass functions of the two clusters are similar, but the GU CMa cluster is older than the cluster around Z CMa by at least a few Myr. Also, the GU CMa cluster is away from any molecular cloud, implying that star formation must have ceased; on the contrary (as already known), star formation is very active in the Z CMa region.

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Section: Search For Young Stars Based On X-ray Datasupporting

confidence: 90%

“…This correlation was obtained by comparing the magnitudes to the mean X-ray luminosities (L X ) estimated for ROSAT sources detected in the Chamaeleon I (Cha I) cloud, adopting the conversion 1 cnt ks −1 = 3 × 10 28 erg s −1 (Feigelson et al 1993).…”

Section: Discussionmentioning

confidence: 99%

Star formation history of Canis Major R1

Gregorio-Hetem¹,

Montmerle

Rodrigues

et al. 2009

A&A

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“…/L bol D 10~4 quiescent phases of class II]IIIs (Feigelson et al 1993 ;Casanova et al 1995 ;. Class on I]I c s, the other hand, show signiÐcantly lower values in L X /L bol both the Ñare and quiescent phases than those of class II]IIIs.…”

Section: X-rays From Brown Dwarfsmentioning

confidence: 92%

ChandraObservation of the ρ Ophiuchi Cloud

Imanishi

Koyama

Tsuboi

2001

ApJ

193

285

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We observed a 17@ ] 17@ region of the o Oph molecular cloud, using the ACIS-I array on board the Chandra X-Ray Observatory. A 100 ks exposure observation revealed D100 X-ray sources above the detection limit of D1028 ergs s~1. About two-thirds of the X-ray sources are identiÐed with an optical and/or IR counterpart, including signiÐcant numbers of class I, II, and III sources and a few brown dwarfs. The X-ray detection rate of class I sources is a surprisingly high 70%. Many X-ray Ñares, possibly because of the magnetic activity, are found from all of the classes. We make systematic spectral studies of the quiescent and Ñare X-rays for all the X-ray sources. The X-ray temperatures and absorptions of class I sources are generally larger than those of class II and III sources. In addition, X-ray Ñares from class I sources show slightly higher duty ratio, temperature, and luminosity than those of more evolved classes. We further give brief results on brown dwarfs, sources in a younger phase than class I, unclassiÐed, and unidentiÐed sources. Details for several selected young stellar objects, including the Ðrst detection of a neutral iron line (6.4 keV) from a class I source (YLW 16A), are separately addressed.

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“…In the case of T54, Feigelson et al (1993) report considerable X-ray luminosity (log(L X ) = 30.5), which is not as extreme as the value for DoAr 21 (log(L X ) 32, Jensen et al 2009). Jensen et al (2009) suggest that strong X-ray emission could be responsible for exciting the PAHs.…”

Section: Comparison With Other Objectsmentioning

confidence: 84%

A newHerschelview of the young star T54: not a transitional disk?

Matrà¹,

Merın²,

Oliveira³

et al. 2012

A&A

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Context. Observations of transitional disks give us an understanding of the formation of planets and planetary systems such as our own. But care must be taken in identifying such sources: the higher spatial resolution of the Herschel Space Observatory provides a new view of the origin of the far-infrared and submillimeter excesses observed. Aims. We review the nature of previously known transitional disks in the Chamaeleon I star-forming region with Herschel data. Methods. We analyze Herschel PACS and SPIRE images of the young star T54, together with ancillary images. We also analyze its spectral energy distribution and indications from optical and mid-infrared spectroscopy. Results. We detect extended emission in the PACS 70 μm image ∼6 off source at a position angle of 196 • from T54. The emission detected at longer wavelengths (PACS 100, 160, SPIRE 250 and 350 μm) is also offset from the position of the star. This suggests that the excess observed in the far-infrared part of the SED is not fully associated with T54. Conclusions. Herschel images show that the far-infrared excess seen in T54 is not due to a transitional disk but to extended emission southwest of the source. The object still shows point-like and now downscaled excess at mid-infrared wavelengths, but its origin cannot be constrained without higher spatial resolution data. However, different indications point towards an evolved disk or extended unresolved emission close to the source.

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ROSAT X-Ray Study of the Chamaeleon I Dark Cloud. I. The Stellar Population

Cited by 146 publications

References 0 publications

Star formation history of Canis Major R1

Star formation history of Canis Major R1

ChandraObservation of the ρ Ophiuchi Cloud

A newHerschelview of the young star T54: not a transitional disk?

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