A fixed point formula for compact almost complex manifolds

Tsuboi, Kenji

doi:10.1215/kjm/1250284707

Cited by 3 publications

(4 citation statements)

References 3 publications

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“…The Chandra observations (Garmire et al 2000 ;E. D. Feigelson et al 2001, private communication) already support the conclusion from ASCA (Koyama 1999 ;Tsuboi 1999) that there are signiÐcant di †erences between younger and older YSOs with respect to the hardness of spectra and the frequency of Ñares.…”

Section: X-raysmentioning

confidence: 69%

“…kT X B 1 kT X B 2È5 Since we focus on the more active YSOs that produce optical jets (and correspond to infrared classes I and II), we assume that the luminosities of the two components are the same order of magnitude and that the total X-ray luminosity is substantially larger than the typical revealed T Tauri star, e.g., ergs s~1. Of course, can be L X B 1031 L X even higher during large Ñares (Feigelson & Montmerle 1999 ;Tsuboi 1999 ;Stelzer, & Hambaryan Neuha user, 2000). As in the discussion of the hot spot radiation in°2.3, the calculation of the e †ects of the X-rays is complicated by the extended nature of the emitting regions and by the lack of relevant observational information on their physical properties.…”

Section: X-raysmentioning

confidence: 99%

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Heating and Ionization ofX‐Winds

Shang

Glassgold

Shu

et al. 2002

ApJ

159

155

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In order to compare the X-wind with observations, one needs to be able to calculate its thermal and ionization properties. We formulate the physical basis for the streamline-by-streamline integration of the ionization and heat equations of the steady X-wind. In addition to the well-known processes associated with the interaction of stellar and accretion funnel hot spot radiation with the wind, we include X-ray heating and ionization, mechanical heating, and a revised calculation of ambipolar di †usion heating. The mechanical heating arises from Ñuctuations produced by star-disk interactions of the time-dependent X-wind that are carried by the wind to large distances where they are dissipated in shocks, MHD waves, and turbulent cascades. We model the time-averaged heating by the scale-free volumetric heating rate, where o and v are the local mass density and wind speed, respectively, s is the distance ! mech \ aov3s~1, from the origin, and a is a phenomenological constant. When we consider a partially revealed but active young stellar object, we Ðnd that choosing a D 10~3 in our numerical calculations produces temperatures and electron fractions that are high enough for the X-wind jet to radiate in the optical forbidden lines at the level and on the spatial scales that are observed. We also discuss a variety of applications of our thermal-chemical calculations that can lead to further observational checks of X-wind theory.

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Section: X-raysmentioning

confidence: 69%

Section: X-raysmentioning

confidence: 99%

Heating and Ionization ofX‐Winds

Shang

Glassgold

Shu

et al. 2002

ApJ

159

155

View full text Add to dashboard Cite

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“…X-rays from class I sources (the late phase of protostars) have been reported in deep ASCA and ROSAT images of the o Ophiuchi cloud (Koyama et al 1994 ;Casanova et al 1995 ;Kamata et al 1997 ;Grosso et al 1997Carkner, Kozak, & Feigelson 1998 ;Tsuboi 1999 ;Tsuboi et al 2000 ;Grosso 2001). However, possible contamination from nearby TTSs (or others) would not be removed with the limited spatial resolution of ASCA.…”

Section: Introductionmentioning

confidence: 99%

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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“…Recent space observations of solar and stellar ares have r e v ealed that there is a universal correlation between the peak temperature (T) of a are and its volume emission measure (EM= n 2 V ), such t h a t EMincreases with increasing T, w h e r e n is the electron number density and V is the volume (Watanabe 1983, Stern 1992, Feldman et al 1995, 1996, Yuda et al 1997). This correlation is extrapolated to not only solar microares (Shimizu 1995) but also protostellar ares , Tsuboi et al 1998, Tsuboi 1999. Figure 1 shows the EM-T relation for solar and stellar ares, including solar microares and protostellar ares.…”

Section: Introductionmentioning

confidence: 97%

A Hertzsprung‐Russell–like Diagram for Solar/Stellar Flares and Corona: Emission Measure versus Temperature Diagram

Shibata

Yokoyama

2002

ApJ

139

103

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In our previous paper, we have presented a theory to explain the observed universal correlation between the emission measure (EM = n 2 V ) and temperature (T) for solar/stellar ares on the basis of the magnetic reconnection model with heat conduction and chromospheric evaporation. Here n is the electron density a n d V is the volume. By extending our theory to general situations, we examined the EM-T diagram in detail, and found the following properties: 1) The universal correlation sequence (\main sequence ares") with EM/ T 17=2 corresponds to the case of constant heating ux or equivalently the case of constant magnetic eld strength in the reconnection model. 2) The EM-T diagram has a forbidden region, where gas pressure of ares exceeds magnetic pressure. 3) There is a coronal branch with EM / T 15=2 for T < 10 7 K, and EM/ T 13=2 for T > 10 7 K. This branch is situated left side of the main sequence ares in the EM-T diagram. 4) There is another forbidden region determined by the length of are loop; a lower limit of are loop is 10 7 cm. Small ares near this limit correspond to nanoares observed by SOHO/EIT. 5) We can plot are evolution track o n t h e EM-T diagram. A are evolves from the coronal branch to main sequence ares, then returns to the coronal branch eventually. These properties of the EM-T diagram are similar to those of the HR diagram for stars, and thus we propose that the EM-T diagram is quite useful to estimate the physical quantities (loop length, heating ux, magnetic eld strength, total energy and so on) of ares and corona when there is no spatially resolved imaging observations.

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A fixed point formula for compact almost complex manifolds

Cited by 3 publications

References 3 publications

Heating and Ionization ofX‐Winds

Heating and Ionization ofX‐Winds

ChandraObservation of the ρ Ophiuchi Cloud

A Hertzsprung‐Russell–like Diagram for Solar/Stellar Flares and Corona: Emission Measure versus Temperature Diagram

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