Abstract
To investigate the formation and early evolution of stars, astronomers study the x-ray emission of T Tauri stars, which are young, solar-mass stars called pre–main sequence stars. Two Earth-orbiting x-ray satellites, the Röntgen X-ray Satellite (ROSAT) and the Advanced Satellite for Cosmology and Astrophysics (ASCA), have discovered x-ray emission from young protostars, called Class I objects. Many T Tauri stars were detected as x-ray sources by ROSAT. X-ray luminosity functions and correlations with other stellar parameters can be studied and used to investigate the x-ray emission mechanism. From the ROSAT data hundreds of T Tauri stars have been discovered, some of which are located outside regions of ongoing star formation. Stellar x-rays also irradiate circumstellar disks, regions where planets may form, so x-ray emission data from T Tauri stars may also be used to investigate the formation of planets.
References
124
Referenced
71
-
Adam F., Lada C., Shu F., Astrophys. J. 312, 788 (1987);
(
10.1086/164924
) / Astrophys. J. by Adam F. (1987) - André P., Montmerle T., ibid. 420, 837 (1994); / ibid. by André P. (1994)
- ; review by
-
Shu F., Adams F., Lizano S., Annu. Rev. Astron. Astrophys. 25, 23 (1987).
(
10.1146/annurev.aa.25.090187.000323
) / Annu. Rev. Astron. Astrophys. by Shu F. (1987) - The HR diagram is a plot of stellar luminosity versus temperature. The effective temperature ( T eff ) of a star is equivalent to its spectral type which can be determined from the appearance and strength of absorption lines in the spectrum of the star. The sequence of spectral types OBAFGKM runs from massive hot O stars to low-mass cold M stars. The position on the vertical axis in the HR diagram is given as luminosity Class from I for supergiants (large surface very luminous) to VI for small subdwarfs. Each spectral type is subdivided by arabic numbers for example a G2.5V star (such as 16 Cyg) is slightly colder than our sun (type G2V = 5780 K effective surface temperature). See Fig. 1 for an HR diagram.
- They were first studied and recognized as being young by George Herbig and have spectral types B or A (or early F) and display emission lines (indicated by the letter e ). See
-
Palla F., Stahler S., Astrophys. J. 418, 414 (1993);
(
10.1086/173402
) / Astrophys. J. by Palla F. (1993) - ; P. Thé M. Pérez E. van den Heuvel Eds. The Nature and Evolutionary Status of Herbig Ae/Be Stars (ASP Conf. Ser. 62 Astronomical Society of the Pacific San Francisco CA 1993).
- Magnetic fields in TTS were measured to be ∼1 kG [
-
Basri G., Marcy G., Valenti J., Astrophys. J. 390, 622 (1992);
(
10.1086/171312
) / Astrophys. J. by Basri G. (1992) - Guenther E., Emerson J., Astron. Astrophys. 309, 777 (1996)]. / Astron. Astrophys. by Guenther E. (1996)
- F. Walter and D. Barry in The Sun in Time C. Sonett M. Giampapa M. Matthews Eds. (Univ. of Arizona Press Tucson 1991) pp. 633-657
- T. Montmerle E. Feigelson J. Bouvier P. André in Protostars and Planets III E. Levy and J. Lunine Eds. (Univ. of Arizona Press Tucson 1993) pp. 689-717;
-
Gagné M., Caillault J.-P., Astrophys. J. 437, 361 (1994).
(
10.1086/175002
) / Astrophys. J. by Gagné M. (1994) -
Rydgren A., Zak D., Vrba F., Chugainov P., Zaitseva G., Astron. J. 89, 1015 (1984);
(
10.1086/113597
) / Astron. J. by Rydgren A. (1984) - Bouvier J., Cabrit S., Fernandez M., Martı́n E., Matthews J., Astron. Astrophys. 272, 176 (1993); / Astron. Astrophys. by Bouvier J. (1993)
-
Edwards S., et al., Astron. J. 106, 372 (1993);
(
10.1086/116646
) / Astron. J. by Edwards S. (1993) - Choi P., Herbst W., ibid. 111, 283 (1996). / ibid. by Choi P. (1996)
-
Strom K., Strom S., Edwards S., Cabrit S., Skrutskie M., Astron. J. 97, 1451 (1989);
(
10.1086/115085
) / Astron. J. by Strom K. (1989) - Beckwith S., Sargent A., Chini R., Güsten R., ibid. 99, 924 (1990); / ibid. by Beckwith S. (1990)
- ; reviews by
-
Beckwith S., Sargent A., Nature 383, 139 (1996);
(
10.1038/383139a0
) / Nature by Beckwith S. (1996) 10.1126/science.276.5317.1355
-
O’Dell C., Wen Z., Hu X., Astrophys. J. 410, 696 (1993);
(
10.1086/172786
) / Astrophys. J. by O’Dell C. (1993) -
; M. McCaughrean and C. O’Dell Astron. J. 111 1996;
(
10.1086/117934
) -
Burrows C., et al., Astrophys. J. 473, 437 (1996).
(
10.1086/178156
) / Astrophys. J. by Burrows C. (1996) -
Elias J., Astrophys. J. 224, 857 (1978);
(
10.1086/156436
) / Astrophys. J. by Elias J. (1978) -
Kenyon S., Dobrzycka D., Hartmann L., Astron. J. 108, 1872 (1994);
(
10.1086/117200
) / Astron. J. by Kenyon S. (1994) - ; T. Preibisch and M. Smith Astron. Astrophys. in press. The astrometry satellite Hipparcos has measured parallaxes from which distances have been calculated. Averaging the distances of five TTS in Taurus yields 140 ± 14 pc for the distance of the Taurus association. Individual distances of the five Taurus TTS observed by Hipparcos have a signal-to-noise ratio of only 3 for the visual magnitude of 10 to 11 and the precision of the Hipparcos distance of the Herbig Ae/Be star AB Aur (visual magnitude is 7) is the best distance measured with an error of 20 pc [R. Wichmann U. Bastian J. Krautter I. Jankovics S. M. Rucinski data presented at the European Space Agency conference on Hipparcos results Venice 12 to 16 May 1997].
- Rucinski S., Krautter J., Astron. Astrophys. 121, 217 (1983); / Astron. Astrophys. by Rucinski S. (1983)
-
Gregorio-Hetem J., Lépine J., Quast G., Torres C., de la Reza R., Astron. J. 103, 549 (1992).
(
10.1086/116082
) / Astron. J. by Gregorio-Hetem J. (1992) -
Boss A., Astrophys. J. 410, 157 (1993);
(
10.1086/172734
) / Astrophys. J. by Boss A. (1993) 10.1093/mnras/264.4.798
- The spectral energy distribution in the range of λ ≃ 2 to ∼25 μm can be approximated by a power law of the form λ F λ = λ n (1).
- The term Class O object denotes an even earlier evolutionary phase with strong submillimeter excess and radio emission [
-
André P., Ward-Thompson D., Barsony M., Astrophys. J. 406, 122 (1993)].
(
10.1086/172425
) / Astrophys. J. by André P. (1993) - Stahler S., ibid. 274, 822 (1983). / ibid. by Stahler S. (1983)
-
J. Najita and F. Shu ibid. 429 808 (1994); F. Shu et al. ibid. p. 781; F. Shu J. Najita S. Ruden S. Lizano ibid. p. 797.
(
10.1086/174365
) - Reviews by G. Herbig Adv. Astron. Astrophys 1 47 (1962);
-
Appenzeller I., Mundt R., Astron. Astrophys. Rev. 1, 291 (1989);
(
10.1007/BF00873081
) / Astron. Astrophys. Rev. by Appenzeller I. (1989) -
Bertout C., Annu. Rev. Astron. Astrophys. 27, 351 (1989).
(
10.1146/annurev.aa.27.090189.002031
) / Annu. Rev. Astron. Astrophys. by Bertout C. (1989) - G. Herbig in Problems of Physics and Evolution of the Universe L. Mirzoyan Ed. (Academy of Science of Armenia Erevan 1978) pp. 171–183.
-
Soderblom D., et al., Astron. J. 106, 1059 (1993);
(
10.1086/116704
) / Astron. J. by Soderblom D. (1993) - ; S. Randich N. Aharpour R. Pallavicini C. Prosser J. Stauffer Astron. Astrophys. in press; J. Stauffer et al. Astrophys. J. 479 776 (1997).
-
Mundt R., et al., Astrophys. J. 269, 229 (1983);
(
10.1086/161033
) / Astrophys. J. by Mundt R. (1983) - Strom K., et al., ibid. 362, 168 (1990). / ibid. by Strom K. (1990)
- A wTTS either shows weak Hα emission above the continuum or emission filling in the absorption. G-type TTS generally show no Hα emission above the continuum and emission can only be inferred by subtracting a template spectrum of an inactive star. The term naked TTS introduced for TTS discovered by EO reflects the interpretation that accretion has come to a halt in TTS without emission above the continuum because they no longer have a disk. Some wTTS do show far-IR or submillimeter excess emission and are not naked. A naked TTS however displays a blackbody spectrum like that of a normal star without any circumstellar material. Naked TTS show Hα emission filling in the absorption and are therefore wTTS [
-
Walter F., Astrophys. J. 306, 573 (1986);
(
10.1086/164367
) / Astrophys. J. by Walter F. (1986) -
___, Brown A., Mathieu R., Myers P., Vrba F., Astron. J. 96, 297 (1988)].
(
10.1086/114809
) / Astron. J. by ___ (1988) -
Bertout C., Basri G., Bouvier J., Astrophys. J. 330, 350 (1988);
(
10.1086/166476
) / Astrophys. J. by Bertout C. (1988) -
Königl A., Astrophys. J. Lett. 370, L39 (1991);
(
10.1086/185972
) / Astrophys. J. Lett. by Königl A. (1991) - ; M. Camenzind Rev. Mod. Astron. 3 (1990);
-
Armitage P., Clarke C., Mon. Not. R. Astron. Soc. 280, 458 (1996).
(
10.1093/mnras/280.2.458
) / Mon. Not. R. Astron. Soc. by Armitage P. (1996) - Leinert C., et al., Astron. Astrophys. 278, 129 (1993); / Astron. Astrophys. by Leinert C. (1993)
-
Ghez A., Neugebauer G., Matthews K., Astron. J. 106, 2005 (1993);
(
10.1086/116782
) / Astron. J. by Ghez A. (1993) -
Simon M., et al., Astrophys. J. 443, 625 (1995);
(
10.1086/175554
) / Astrophys. J. by Simon M. (1995) - ; review by
-
Mathieu R., Annu. Rev. Astron. Astrophys. 32, 405 (1994).
(
10.1146/annurev.aa.32.090194.002341
) / Annu. Rev. Astron. Astrophys. by Mathieu R. (1994) -
D’Antona F., Mazzitelli I., Astrophys. J. Suppl. 90, 467 (1994).
(
10.1086/191867
) / Astrophys. J. Suppl. by D’Antona F. (1994) -
Casanova S., Montmerle T., Feigelson E., André P., Astrophys. J. 439, 752 (1995).
(
10.1086/175214
) / Astrophys. J. by Casanova S. (1995) -
Ryter C., Astrophys. Space Sci. 236, 285 (1996).
(
10.1007/BF00645150
) / Astrophys. Space Sci. by Ryter C. (1996) - The ROSAT x-ray satellite (59) was launched on 1 June 1990. ROSAT is sensitive to the soft x-ray range from 0.1 to 2.4 keV (124 to 5 Å). The high-resolution imager (HRI) has ∼5 arc sec spatial resolution and the PSPCs offer sufficient spectral resolution (0.43 at 0.93 keV) for binning the x-rays into five independent energy bands. In addition there is a wide-field camera onboard ROSAT for the extreme UV (20 to 200 eV or 620 to 62 Å). After the RASS which was performed with the PSPC ROSAT has carried out many pointed observations with the PSPC and the HRI.
- The Japanese x-ray satellite ASCA (60) was launched on 20 February 1993. It is equipped with four thin-foil x-ray telescopes together with charge-coupled device (CCD) cameras and gas imaging detectors and yields high spectral resolution ( E /Δ E ≃ 50 at 6 keV where E is the energy of the x-ray). Its spatial resolution between 1 and 3 arc min is lower compared with ROSAT and its energy range (0.5 to 10 keV or 25 to 1.2 Å) is shifted toward higher energies.
-
Grosso N., et al., Nature 387, 56 (1997).
(
10.1038/387056a0
) / Nature by Grosso N. (1997) -
K. Koyama K. Hamaguchi S. Ueno N. Kobayashi E. Feigelson Publ. Astron. Soc. Japan 48 719 (1996).
(
10.1093/pasj/48.5.L87
) - R. Neuhäuser and T. Preibisch Astron. Astrophys. in press.
- T. Preibisch ibid. in press.
-
Hayashi M., Shibata K., Matsumoto R., Astrophys. J. 468, 37 (1996).
(
10.1086/310222
) / Astrophys. J. by Hayashi M. (1996) -
Ku W., Chanan G., Astrophys. J. Lett. 234, L59 (1979);
(
10.1086/183109
) / Astrophys. J. Lett. by Ku W. (1979) - Gahm G., ibid. 242, L163 (1980); / ibid. by Gahm G. (1980)
-
; E. Feigelson and G. Kriss ibid. 248 L35 (1981);
(
10.1086/183618
) -
Walter F., Kuhi L., Astrophys. J. 250, 254 (1981).
(
10.1086/159370
) / Astrophys. J. by Walter F. (1981) -
Montmerle T., Koch-Miramond L., Falgaronne E., Grindlay J., Astrophys. J. 269, 182 (1983);
(
10.1086/161029
) / Astrophys. J. by Montmerle T. (1983) - Walter F., Kuhi L., ibid. 284, 194 (1984); / ibid. by Walter F. (1984)
- ; T. Preibisch H. Zinnecker J. Schmitt Astron. Astrophys. Lett. 279 L33 (1993).
- Neuhäuser R., Sterzik M., Schmitt J., Wichmann R., Krautter J., Astron. Astrophys. 297, 381 (1995). / Astron. Astrophys. by Neuhäuser R. (1995)
- J. Alcalá et al. Astron. Astrophys. Suppl. 114 109 (1995);
- Alcalá J., et al., Astron. Astrophys. 319, 184 (1997); / Astron. Astrophys. by Alcalá J. (1997)
- ; E. Covino et al. in preparation.
- Neuhäuser R., Sterzik M., Schmitt J., Wichmann R., Krautter J., Astron. Astrophys. 295, L5 (1995); / Astron. Astrophys. by Neuhäuser R. (1995)
- Wichmann R., et al., ibid. 312, 439 (1996); / ibid. by Wichmann R. (1996)
- ; J. Bouvier et al. ibid. 318 495 (1997).
-
J. Alcalá L. Terranegra R. Wichmann C. Chavarria J. Krautter Astron. Astrophys. Suppl. 119 7 (1996); J. Alcalá C. Chavarrı́a L. Terranegra in preparation.
(
10.1051/aas:1996224
) - Wichmann R., et al., Astron. Astrophys. 320, 185 (1997); / Astron. Astrophys. by Wichmann R. (1997)
- ; J. Krautter et al. ibid. in press; R. Wichmann M. Sterzik J. Krautter A. Metanomski W. Voges ibid. in press; R. Wichmann et al. ibid. 320 185 (1997).
-
Feigelson E., Casanova S., Montmerle T., Guibert J., Astrophys. J. 416, 623 (1993);
(
10.1086/173264
) / Astrophys. J. by Feigelson E. (1993) -
Huenemoerder D., Lawson W., Feigelson E., Mon. Not. R. Astron. Soc. 271, 967 (1994);
(
10.1093/mnras/271.4.967
) / Mon. Not. R. Astron. Soc. by Huenemoerder D. (1994) - Lawson W., Feigelson E., Huenemoerder D., ibid. 280, 1071 (1996). / ibid. by Lawson W. (1996)
-
Strom K., Strom S., Astrophys. J. 424, 237 (1994);
(
10.1086/173886
) / Astrophys. J. by Strom K. (1994) - Carkner L., Feigelson E., Koyama K., Montmerle T., Reid N., ibid. 464, 286 (1996). / ibid. by Carkner L. (1996)
-
Stauffer J., Caillault J.-P., Gagné M., Prosser C., Hartmann L., Astrophys. J. Suppl. 91, 625 (1994);
(
10.1086/191951
) / Astrophys. J. Suppl. by Stauffer J. (1994) -
Stern R., et al., Astrophys. J. 427, 808 (1994).
(
10.1086/174187
) / Astrophys. J. by Stern R. (1994) -
Pallavicini R., et al., Astrophys. J. 248, 279 (1981);
(
10.1086/159152
) / Astrophys. J. by Pallavicini R. (1981) -
Bouvier J., Astron. J. 99, 946 (1990).
(
10.1086/115386
) / Astron. J. by Bouvier J. (1990) - J. Bouvier M. Forestini S. Allain in preparation.
- Neuhäuser R., Sterzik M., Torres G., Martı́n E., Astron. Astrophys. 299, L13 (1995); / Astron. Astrophys. by Neuhäuser R. (1995)
- ; A. Magazzù et al. Astron. Astrophys. Suppl. in press.
- R. Neuhäuser G. Torres M. Sterzik S. Randich Astron. Astrophys. in press.
-
Jones B., Herbig G., Astron. J. 84, 1872 (1979);
(
10.1086/112619
) / Astron. J. by Jones B. (1979) -
Gomez de Castro A., Pudritz R., Astrophys. J. 409, 748 (1993).
(
10.1086/172704
) / Astrophys. J. by Gomez de Castro A. (1993) - S. Frink S. Röser R. Neuhäuser M. Sterzik Astron. Astrophys. in press.
- Sterzik M., Alcalá J., Neuhäuser R., Schmitt J., ibid. 297, 418 (1995); / ibid. by Sterzik M. (1995)
- ; M. Sterzik and R. Durisen ibid. 304 L9 (1995); P. Armitage and C. Clarke Mon. Not. R. Astron. Soc. in press.
-
Feigelson E., Astrophys. J. 468, 306 (1996).
(
10.1086/177691
) / Astrophys. J. by Feigelson E. (1996) - Bok B., Reilly E., ibid. 105, 255 (1947); / ibid. by Bok B. (1947)
-
Lynds B., Astrophys. J. Suppl. 12, 163 (1962) ;
(
10.1086/190123
) / Astrophys. J. Suppl. by Lynds B. (1962) -
Magnani L., Blitz L., Mundy L., Astrophys. J. 295, 402 (1985).
(
10.1086/163385
) / Astrophys. J. by Magnani L. (1985) -
Micela G., Sciortino S., Favata F., Astrophys. J. 412, 618 (1993);
(
10.1086/172948
) / Astrophys. J. by Micela G. (1993) -
Briceño C., Hartmann L., Stauffer J., Gagné M., Stern S., Astron. J. 113, 740 (1997).
(
10.1086/118293
) / Astron. J. by Briceño C. (1997) - However having obtained the Li strength from spectra with sufficient resolution one has to account for the presence of an active chromosphere transition region which will overionize Li resulting in an apparent underabundance [
- Houdebine E., Doyle J., Astron. Astrophys. 302, 861 (1995)]. / Astron. Astrophys. by Houdebine E. (1995)
- W. Hoff et al. in preparation.
-
B. Gould Am. J. Sci. Arts 8 325 (1874);
(
10.2475/ajs.s3-8.47.325
) - Comerón F., Torra J., Gómez A., Astron. Astrophys. 286, 789 (1994); / Astron. Astrophys. by Comerón F. (1994)
-
; review by W. Pöppel Fundam. Cosmic Phys. 118 (1996).
(
10.1215/01636545-1996-65-118
) - Favata F., Barbera M., Micela G., Sciortino S., Astron. Astrophys. 277, 428 (1993); / Astron. Astrophys. by Favata F. (1993)
- Tagliaferri G., Cutispoto G., Pallavicini R., Randich S., Pasquini L., ibid. 285, 272 (1994); / ibid. by Tagliaferri G. (1994)
-
Jeffries R., Mon. Not. R. Astron. Soc. 273, 559 (1995).
(
10.1093/mnras/273.3.559
) / Mon. Not. R. Astron. Soc. by Jeffries R. (1995) -
Walter F., Boyd W., Astrophys. J. 370, 318 (1991);
(
10.1086/169817
) / Astrophys. J. by Walter F. (1991) -
Miller G., Scalo J., Astrophys. J. Suppl. 41, 512 (1979).
(
10.1086/190629
) / Astrophys. J. Suppl. by Miller G. (1979) -
Glassgold A., Najita J., Igea J., Astrophys. J. 480, 344 (1997).
(
10.1086/303952
) / Astrophys. J. by Glassgold A. (1997) -
Trümper J., Adv. Space Res. 2, 241 (1983).
(
10.1016/0273-1177(82)90070-9
) / Adv. Space Res. by Trümper J. (1983) - Y. Tanaka H. Inoue S. Holt Publ. Astron. Soc. Japan 46 L37 (1994).
- I thank J. Alcalá J. Bouvier E. Covino W. Hoff T. Montmerle G. Morfill T. Preibisch R. Pudritz J. Schmitt M. Sterzik J. Trümper R. Wichmann and the referees for useful discussion and providing data before publication and the Deutsche Forschungsgemeinschaft Physics of Star Formation program for financial support. The ROSAT project is supported by the Max-Planck-Gesellschaft and the German government.
Dates
Type | When |
---|---|
Created | 23 years, 1 month ago (July 27, 2002, 5:45 a.m.) |
Deposited | 8 months, 2 weeks ago (Dec. 8, 2024, 1:48 p.m.) |
Indexed | 3 months, 1 week ago (May 20, 2025, 8:44 p.m.) |
Issued | 28 years, 2 months ago (May 30, 1997) |
Published | 28 years, 2 months ago (May 30, 1997) |
Published Print | 28 years, 2 months ago (May 30, 1997) |
@article{Neuha_user_1997, title={Low-Mass Pre-Main Sequence Stars and Their X-ray Emission}, volume={276}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.276.5317.1363}, DOI={10.1126/science.276.5317.1363}, number={5317}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Neuhäuser, Ralph}, year={1997}, month=may, pages={1363–1370} }