The detection of ultrahigh-energy neutrinos, with energies in the PeV range or above, is a topic of great interest in modern astroparticle physics. The importance comes from the fact that these neutrinos point back to the most energetic particle accelerators in the Universe and provide information about their underlying acceleration mechanisms. Atmospheric neutrinos are a background for these challenging measurements, but their rate is expected to be negligible above &#x2248;1&#x2009;PeV. In this work we describe the feasibility to study ultrahigh-energy neutrinos based on the Earth-skimming technique, by detecting the charged leptons produced in neutrino-nucleon interactions in a high mass target. We propose to detect the charged leptons, or their decay products, with the High Altitude Water Cherenkov (HAWC) observatory and use as a large-mass target for the neutrino interactions the Pico de Orizaba volcano, the highest mountain in Mexico. In this work we develop an estimate of the detection rate using a geometrical model to calculate the effective area of the observatory. Our results show that it may be feasible to perform measurements of the ultrahigh-energy neutrino flux from cosmic origin during the expected lifetime of the HAWC observatory.

Hermes Le&#xf3;n Vargas

Andr&#xe9;s Sandoval

Ernesto Belmont

Rub&#xe9;n Alfaro

Capability of the HAWC Gamma-Ray Observatory for the Indirect Detection of Ultrahigh-Energy Neutrinos

We present an extensive analysis of the relationship between star formation rate surface density (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.03148pt" id="M1" height="12.7178pt" version="1.1" viewBox="-0.0498162 -9.68632 33.2304 12.7178" width="33.2304pt"><g transform="matrix(.013,0,0,-0.013,0,.007)"><path id="g119-65" d="M697 -46L668 -39C637 -126 611 -142 545 -142H163L474 298L206 694H483C558 694 584 688 600 668C615 651 627 625 639 580L667 585L655 739H70V714L378 254L53 -203V-228H655L697 -46Z"/></g><g transform="matrix(.013,0,0,-0.013,11.966,0)"><path id="g121-81" d="M409 504C401 567 396 607 392 642C354 654 312 665 266 665C137 665 60 583 60 487C60 374 161 325 225 290C300 250 355 215 355 141C355 68 311 21 235 21C131 21 86 122 71 183L41 176C48 128 61 42 68 21C78 16 93 8 118 0C142 -7 175 -15 216 -15C349 -15 438 69 438 174C438 287 344 333 265 374C186 414 138 449 138 522C138 576 172 631 249 631C336 631 363 562 380 499L409 504Z"/></g><g transform="matrix(.013,0,0,-0.013,17.971,0)"><path id="g121-68" d="M493 503C489 551 484 614 483 650H43V622C120 616 128 611 128 525V126C128 40 120 34 40 28V0H312V28C221 34 213 40 213 126V307H316C407 307 412 296 424 227H453V420H424C412 355 407 346 316 346H213V584C213 613 216 616 246 616H322C398 616 419 607 436 579C449 559 455 539 464 499L493 503Z"/></g><g transform="matrix(.013,0,0,-0.013,24.848,0)"><path id="g121-80" d="M631 18C609 24 585 35 559 65C534 91 514 117 478 169C448 214 406 281 389 313C462 346 516 399 516 485C516 545 490 590 449 616C412 641 363 650 290 650H42V622C120 615 128 612 128 527V125C128 40 120 34 38 28V0H300V28C221 34 212 40 212 125V284H244C295 284 312 272 329 244C359 195 395 133 430 84C475 19 516 -3 592 -7C603 -8 615 -8 627 -8L631 18ZM212 316V563C212 591 215 602 223 607C231 613 248 617 277 617C352 617 423 577 423 469C423 415 407 375 368 345C343 324 310 316 260 316H212Z"/></g></svg>) and molecular gas surface density (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.181479pt" id="M2" height="12.8678pt" version="1.1" viewBox="-0.0498162 -9.68632 27.0071 12.8678" width="27.0071pt"><g transform="matrix(.013,0,0,-0.013,0,.007)"><use xlink:href="#g119-65"/></g><g transform="matrix(.013,0,0,-0.013,11.966,0)"><path id="g121-70" d="M729 650H468V622C546 615 554 610 554 527V365H213V527C213 610 221 616 297 622V650H38V622C120 616 128 611 128 527V123C128 39 120 34 40 28V0H303V28C221 34 213 40 213 123V322H554V123C554 39 546 34 460 28V0H728V28C647 34 639 39 639 123V527C639 610 647 615 729 622V650Z"/></g><g transform="matrix(.0091,0,0,-0.0091,21.924,3.132)"><path id="g50-51" d="M414 144C384 79 371 75 317 75H135L276 221C367 316 408 376 408 465C408 570 327 635 237 635C179 635 131 609 100 575L42 494L67 471C94 510 138 565 205 565C277 565 321 517 321 435C321 348 258 270 195 195C146 137 88 81 33 26V0H411C423 44 433 88 446 135L414 144Z"/></g></svg>) at sub-kpc scale in the elliptical galaxy Centaurus A (also known as NGC 5128) at the distance 3.8 Mpc. <sup>12</sup>CO (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-1.928801pt" id="M3" height="10.5647pt" version="1.1" viewBox="-0.0498162 -8.6359 5.99765 10.5647" width="5.99765pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-75" d="M429 650H175L169 622C251 614 259 612 244 532L174 152C163 91 152 37 135 -6C109 -72 67 -101 23 -113L33 -144C45 -143 73 -134 102 -119C186 -76 229 -1 254 133L327 532C341 609 347 613 423 622L429 650Z"/></g></svg> = 2-1) data from Atacama Large Millimetre/Sub-Millimetre Array SV data with very high resolution (2.9′′, 0.84′′), as well as 24 <i>μ</i>m data from the Spitzer Space Telescope, were used. This is one of the first studies of the SF law on Centaurus A at this very high spatial resolution. The results showed a breakdown in star formation law with a <span class="inline_break"><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="32.222pt" style="vertical-align:-0.3499298pt" id="M4" height="8.69875pt" version="1.1" viewBox="-0.0498162 -8.34882 32.222 8.69875"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-49" d="M241 635C89 635 35 457 35 312C35 153 89 -12 240 -12C390 -12 443 166 443 312C443 466 390 635 241 635ZM238 602C329 602 354 454 354 312C354 172 330 22 240 22C152 22 124 173 124 313S148 602 238 602Z"/></g><g transform="matrix(.013,0,0,-0.013,6.24,0)"><path id="g113-47" d="M113 -12C146 -12 170 11 170 46C170 78 146 103 114 103S58 78 58 46C58 11 82 -12 113 -12Z"/></g><g transform="matrix(.013,0,0,-0.013,9.204,0)"><path id="g113-53" d="M456 178V225H360V632H320C217 496 115 347 20 206V178H280V106C280 40 276 34 189 27V0H445V27C364 34 360 39 360 106V178H456ZM280 225H82C149 335 214 431 278 520H280V225Z"/></g><g transform="matrix(.013,0,0,-0.013,15.444,0)"><path id="g113-58" d="M244 635C114 635 38 519 38 422C38 317 111 240 217 240C236 240 255 244 277 256L345 292C311 140 203 39 59 15L64 -15C89 -15 150 -5 204 17C339 72 440 202 440 386C440 521 368 635 244 635ZM228 602C326 602 352 479 352 390C352 370 351 347 348 324C327 308 293 296 258 296C174 296 124 369 124 458C124 517 152 602 228 602Z"/></g><g transform="matrix(.013,0,0,-0.013,24.591,0)"><path id="g117-37" d="M535 290V340H323V533H265V340H52V290H265V84H323V290H535ZM535 -22V28H52V-22H535Z"/></g></svg><span class="ibiop"></span><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="21.684pt" style="vertical-align:-0.3499298pt" height="8.69875pt" version="1.1" viewBox="35.0771838 -8.34882 21.684 8.69875"><g transform="matrix(.013,0,0,-0.013,35.127,0)"><use xlink:href="#g113-49"/></g><g transform="matrix(.013,0,0,-0.013,41.367,0)"><use xlink:href="#g113-47"/></g><g transform="matrix(.013,0,0,-0.013,44.331,0)"><use xlink:href="#g113-49"/></g><g transform="matrix(.013,0,0,-0.013,50.571,0)"><path id="g113-54" d="M153 550H386L412 615L406 623H120L82 318C104 327 142 338 184 338C294 338 347 275 347 187C347 112 305 39 221 39C160 39 119 71 97 89C88 97 80 96 71 90C59 80 50 67 49 57C48 45 52 36 66 23C80 9 123 -12 169 -12C221 -11 288 15 342 59C403 109 431 165 431 225C431 308 366 395 238 395C212 395 165 379 127 364L153 550Z"/></g></svg></span> index relating <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.03148pt" id="M5" height="12.7178pt" version="1.1" viewBox="-0.0498162 -9.68632 33.2304 12.7178" width="33.2304pt"><g transform="matrix(.013,0,0,-0.013,0,.007)"><use xlink:href="#g119-65"/></g><g transform="matrix(.013,0,0,-0.013,11.966,0)"><use xlink:href="#g121-81"/></g><g transform="matrix(.013,0,0,-0.013,17.971,0)"><use xlink:href="#g121-68"/></g><g transform="matrix(.013,0,0,-0.013,24.848,0)"><use xlink:href="#g121-80"/></g></svg> and <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.181479pt" id="M6" height="12.8678pt" version="1.1" viewBox="-0.0498162 -9.68632 27.0071 12.8678" width="27.0071pt"><g transform="matrix(.013,0,0,-0.013,0,.007)"><use xlink:href="#g119-65"/></g><g transform="matrix(.013,0,0,-0.013,11.966,0)"><use xlink:href="#g121-70"/></g><g transform="matrix(.0091,0,0,-0.0091,21.924,3.132)"><use xlink:href="#g50-51"/></g></svg> at 185 pc. A significant correlation exists between surface densities of molecular gas and SFR with very long depletion time (68 Gy). In addition we examined the spatially resolved relationship between velocity dispersion and star formation rate surface density for the outer disk of this galaxy and we found that the average velocity dispersion is equal to 11.78 km/s. The velocity dispersion of the molecular ISM for the outer disk is found to follow a power relation with the star formation rate surface density <span class="inline_break"><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="21.73pt" style="vertical-align:-3.031401pt" id="M7" height="15.2896pt" version="1.1" viewBox="-0.0498162 -12.2582 21.73 15.2896"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-240" d="M548 455L523 469C505 448 490 439 461 439C416 439 374 447 316 447C144 447 23 310 23 161C23 47 89 -12 179 -12C312 -12 429 106 429 244C429 303 419 344 368 386L371 388C404 383 440 378 474 378C507 378 530 411 548 455ZM350 274C350 191 308 25 198 25C144 25 108 75 108 157C108 264 170 395 276 395C296 395 320 384 333 360C347 334 350 316 350 274Z"/></g><g transform="matrix(.013,0,0,-0.013,10.979,0)"><path id="g113-29" d="M774 30C773 39 771 49 769 58C758 52 747 48 732 48C616 48 566 133 514 239C556 327 604 374 702 374C716 374 729 369 737 365C743 361 747 361 752 365C761 373 770 389 770 406C770 426 754 448 726 448C689 448 629 431 577 391C534 358 509 327 489 288C438 384 373 448 262 448C175 448 53 373 53 208C53 98 131 -12 262 -12C377 -12 426 52 472 147C516 51 579 -12 687 -12C713 -12 748 -2 774 30ZM451 198C415 110 363 21 272 21C195 21 145 114 145 240C145 353 194 415 250 415C357 415 409 304 451 198Z"/></g></svg><span class="irelop"></span><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="47.39pt" style="vertical-align:-3.031401pt" height="15.2896pt" version="1.1" viewBox="25.3121838 -12.2582 47.39 15.2896"><g transform="matrix(.013,0,0,-0.013,25.362,0)"><path id="g113-41" d="M300 -147C201 -63 143 98 143 270S200 602 300 686L282 710C136 610 70 450 70 271V270C70 89 136 -72 282 -170L300 -147Z"/></g><g transform="matrix(.013,0,0,-0.013,29.86,.007)"><use xlink:href="#g119-65"/></g><g transform="matrix(.013,0,0,-0.013,41.826,0)"><use xlink:href="#g121-81"/></g><g transform="matrix(.013,0,0,-0.013,47.831,0)"><use xlink:href="#g121-68"/></g><g transform="matrix(.013,0,0,-0.013,54.708,0)"><use xlink:href="#g121-80"/></g><g transform="matrix(.013,0,0,-0.013,62.912,0)"><path id="g113-42" d="M275 270C275 450 212 609 64 710L45 686C145 604 203 442 203 270S147 -63 45 -147L64 -170C213 -68 275 89 275 270Z"/></g><g transform="matrix(.0091,0,0,-0.0091,67.41,-5.741)"><path id="g50-224" d="M563 583C563 664 501 710 433 710C381 710 334 692 285 648C212 582 178 506 149 350L74 -56C49 -190 36 -222 24 -226L30 -257C52 -256 95 -247 121 -229C131 -222 134 -206 165 -21L219 303C254 510 296 665 397 665C447 665 481 626 481 572C481 512 446 457 390 420C367 405 351 400 323 397L302 349C398 338 466 285 466 197C466 117 419 45 306 45C268 45 224 59 198 74L186 50C197 20 228 -14 274 -14C318 -14 359 3 401 26C478 68 554 144 554 225C554 322 493 367 412 396C490 446 563 500 563 583Z"/></g></svg></span>, where <i>β</i> is the slope from the ordinary least square fitting. The value of <i>β</i> is about <span class="inline_break"><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="11.596pt" style="vertical-align:-2.15067pt" id="M8" height="11.439pt" version="1.1" viewBox="-0.0498162 -9.28833 11.596 11.439"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-50" d="M384 0V27C293 34 287 42 287 114V635C232 613 172 594 109 583V559L157 557C201 555 205 550 205 499V114C205 42 199 34 109 27V0H384Z"/></g><g transform="matrix(.013,0,0,-0.013,6.24,0)"><path id="g113-48" d="M368 703H309L44 -163H104L368 703Z"/></g></svg><span class="isep"/><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="17.789pt" style="vertical-align:-2.15067pt" height="11.439pt" version="1.1" viewBox="11.5511838 -9.28833 17.789 11.439"><g transform="matrix(.013,0,0,-0.013,11.601,0)"><path id="g113-111" d="M495 86L479 114C446 82 419 66 409 66C401 66 401 72 406 97C420 166 436 231 453 297C489 435 454 448 428 448C406 448 384 439 354 422C305 394 222 327 161 247H159L183 345C200 415 194 448 173 448C143 448 82 410 23 351L38 325C64 349 95 371 105 371C111 371 116 365 109 336L25 -4L31 -12C50 -4 77 3 107 9C119 69 132 122 145 168C197 254 321 381 370 381C387 381 393 374 378 305L329 95C309 17 320 -12 345 -12C372 -12 430 19 495 86Z"/></g><g transform="matrix(.013,0,0,-0.013,21.759,0)"><path id="g117-132" d="M537 353L508 390C487 357 455 333 417 333C389 333 344 353 309 370C265 391 212 414 172 414C122 414 79 382 50 340L81 307C101 339 134 364 172 364C198 364 245 343 280 326C324 305 375 283 417 283C466 283 507 314 537 353ZM537 168L508 205C487 172 455 148 417 148C389 148 344 168 309 185C265 206 212 229 172 229C122 229 79 197 50 155L81 122C101 154 134 179 172 179C198 179 245 158 280 141C324 120 375 98 417 98C466 98 507 129 537 168Z"/></g></svg><span class="irelop"></span><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="32.221pt" style="vertical-align:-2.15067pt" height="11.439pt" version="1.1" viewBox="32.972183799999996 -9.28833 32.221 11.439"><g transform="matrix(.013,0,0,-0.013,33.022,0)"><path id="g113-51" d="M412 140C382 77 369 73 315 73H129L270 222C362 320 402 379 402 466C402 571 322 635 234 635C177 635 130 609 99 576L42 495L64 475C90 514 133 568 201 568C274 568 318 519 318 435C318 349 255 267 193 193C144 135 87 78 32 23V0H405C417 45 427 89 440 131L412 140Z"/></g><g transform="matrix(.013,0,0,-0.013,39.262,0)"><use xlink:href="#g113-47"/></g><g transform="matrix(.013,0,0,-0.013,42.226,0)"><use xlink:href="#g113-50"/></g><g transform="matrix(.013,0,0,-0.013,48.466,0)"><path id="g113-55" d="M137 343C167 482 260 545 321 574C357 591 397 603 429 609L423 641C382 634 335 622 295 608C189 570 37 457 37 238C37 84 125 -12 242 -12C362 -12 447 89 447 209C447 311 374 393 267 393C247 393 226 386 204 376L137 343ZM227 337C318 337 361 256 361 173C361 105 336 22 258 22C176 22 126 120 126 240C126 266 127 291 132 310C155 323 189 337 227 337Z"/></g><g transform="matrix(.013,0,0,-0.013,57.612,0)"><use xlink:href="#g117-37"/></g></svg><span class="ibiop"></span><svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" width="21.685pt" style="vertical-align:-2.15067pt" height="11.439pt" version="1.1" viewBox="68.0981838 -9.28833 21.685 11.439"><g transform="matrix(.013,0,0,-0.013,68.148,0)"><use xlink:href="#g113-49"/></g><g transform="matrix(.013,0,0,-0.013,74.388,0)"><use xlink:href="#g113-47"/></g><g transform="matrix(.013,0,0,-0.013,77.352,0)"><use xlink:href="#g113-53"/></g><g transform="matrix(.013,0,0,-0.013,83.593,0)"><use xlink:href="#g113-49"/></g></svg></span> and <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.2063904pt" id="M9" height="6.1673pt" version="1.1" viewBox="-0.0498162 -5.96091 6.6501 6.1673" width="6.6501pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-111"/></g></svg> is the power law index of the star formation law. 

Jazeel H. Azeez

Zamri Z. Abidin

C.-Y. Hwang

Zainol A. Ibrahim

Star Formation Law at Sub-kpc Scale in the Elliptical Galaxy Centaurus A as Seen by ALMA

We present a detailed report of the connection between long-duration gamma-ray bursts (GRBs) and their accompanying supernovae (SNe). The discussion presented here places emphasis on how observations, and the modelling of observations, have constrained what we know about GRB-SNe. We discuss their photometric and spectroscopic properties, their role as cosmological probes, including their measured luminosity&#x2013;decline relationships, and how they can be used to measure the Hubble constant. We present a statistical summary of their bolometric properties and use this to determine the properties of the &#x201c;average&#x201d; GRB-SN. We discuss their geometry and consider the various physical processes that are thought to power the luminosity of GRB-SNe and whether differences exist between GRB-SNe and the SNe associated with ultra-long-duration GRBs. We discuss how observations of their environments further constrain the physical properties of their progenitor stars and give a brief overview of the current theoretical paradigms of their central engines. We then present an overview of the radioactively powered transients that have been photometrically associated with short-duration GRBs, and we conclude by discussing what additional research is needed to further our understanding of GRB-SNe, in particular the role of binary-formation channels and the connection of GRB-SNe with superluminous SNe.

Zach Cano

Shan-Qin Wang

Zi-Gao Dai

Xue-Feng Wu

The Observer&#x2019;s Guide to the Gamma-Ray Burst Supernova Connection

Keeping the flying formation of spacecraft is a key problem which needs to be solved in deep space exploration missions. In this paper, the nonlinear dynamic model of formation flying is established and a series of transformations are carried out on this model equation. By using SDRE (State-Dependent Riccati Equation) algorithm, the optimal control of flying formation is realized. Compared with the traditional control method based on the average orbit elements and LQR (Linear Quadratic Regulator) control method, the SDRE control method has higher control precision and is more suitable for the advantages of continuous control in practical engineering. Finally, the parameter values of the sun-earth libration point L2 are substituted in the equation and simulation is performed. The simulation curves of SDRE controller are compared with LQR controller. The results show that the SDRE controllers time cost is less than the LQR controllers and the former&#x2019;s fuel consumption is less than the latter&#x2019;s in the system transition process.

He Zhenqi

Zhang Ke

Lv Meibai

Research on Control Method of Keeping Flight Formation by Using SDRE on the Sun-Earth Libration Points

Development of Kelvin–Helmholtz (KH) instability in solar coronal jets can trigger the wave turbulence considered as one of the main mechanisms of coronal heating. In this review, we have investigated the propagation of normal MHD modes running on three X-ray jets modeling them as untwisted and slightly twisted moving cylindrical flux tubes. The basic physical parameters of the jets are temperatures in the range of 5.2–8.2 MK, particle number densities of the order of <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.2063999pt" id="M1" height="11.7978pt" version="1.1" viewBox="-0.0498162 -11.5914 17.5728 11.7978" width="17.5728pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-50" d="M384 0V27C293 34 287 42 287 114V635C232 613 172 594 109 583V559L157 557C201 555 205 550 205 499V114C205 42 199 34 109 27V0H384Z"/></g><g transform="matrix(.013,0,0,-0.013,6.24,0)"><path id="g113-49" d="M241 635C89 635 35 457 35 312C35 153 89 -12 240 -12C390 -12 443 166 443 312C443 466 390 635 241 635ZM238 602C329 602 354 454 354 312C354 172 330 22 240 22C152 22 124 173 124 313S148 602 238 602Z"/></g><g transform="matrix(.0091,0,0,-0.0091,12.527,-5.741)"><path id="g50-58" d="M247 635C116 635 39 518 39 421C39 315 113 237 221 237C239 237 258 241 281 253L349 289C315 140 204 42 60 19L66 -15C90 -15 153 -5 207 16C344 70 447 199 447 385C447 521 373 635 247 635ZM231 598C329 598 356 478 356 390C356 371 355 347 352 325C330 309 297 297 262 297C179 297 127 369 127 456C127 515 156 598 231 598Z"/></g></svg> cm<sup>−3</sup>, and speeds of 385, 437, and 532 km s<sup>−1</sup>, respectively. For small density contrast between the environment and a given jet, as well as at ambient coronal temperature of 2.0 MK and magnetic field around 7 G, we have obtained that the kink (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.2063904pt" id="M2" height="8.55521pt" version="1.1" viewBox="-0.0498162 -8.34882 31.5818 8.55521" width="31.5818pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-110" d="M766 88L752 113C719 83 690 64 681 64C674 64 672 74 679 103L724 292C758 436 724 448 701 448C680 448 666 442 639 429C594 407 514 350 441 252H439L447 289C476 423 450 448 419 448C398 448 379 441 355 427C307 400 234 344 162 249H160L180 324C203 409 197 448 170 448C144 448 82 413 23 349L35 321C57 343 96 374 108 374C115 374 117 371 111 341C87 227 57 112 24 -6L32 -12C53 -4 81 4 108 6C119 68 134 128 149 171C177 229 309 383 364 383C387 383 388 355 373 282C354 190 330 92 303 -6L309 -12C332 -4 356 3 386 6C396 63 411 122 424 171C458 236 590 383 642 383C658 383 664 369 652 315L603 91C587 20 593 -12 619 -12C642 -12 708 23 766 88Z"/></g><g transform="matrix(.013,0,0,-0.013,13.889,0)"><path id="g117-34" d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z"/></g><g transform="matrix(.013,0,0,-0.013,25.152,0)"><use xlink:href="#g113-50"/></g></svg>) mode propagating on moving untwisted flux tubes can become unstable in the first and second jets at flow speeds of <i>≅</i>348 and 429 km s<sup>−1</sup>, respectively. The KH instability onset in the third jet requires a speed of <i>≅</i>826 km s<sup>−1</sup>, higher than the observed one. The same mode, propagating in weakly twisted flux tubes, becomes unstable at flow speeds of <i>≅</i>361 km s<sup>−1</sup> for the first and of 443 km s<sup>−1</sup> for the second jet. Except the kink mode, the twisted moving flux tube supports the propagation of higher (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-0.6370001pt" id="M3" height="8.98582pt" version="1.1" viewBox="-0.0498162 -8.34882 31.5818 8.98582" width="31.5818pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-110"/></g><g transform="matrix(.013,0,0,-0.013,13.889,0)"><path id="g117-92" d="M512 230V281L75 514V456L453 256V254L75 55V-3L512 230Z"/></g><g transform="matrix(.013,0,0,-0.013,25.152,0)"><use xlink:href="#g113-50"/></g></svg>) MHD modes that can become unstable at accessible jets’ speeds.

Ivan Zhelyazkov

Ramesh Chandra

Abhishek K. Srivastava

Modeling Kelvin&#x2013;Helmholtz Instability in Soft X-Ray Solar Jets

VZLUSAT-1 nanosatellite (scheduled launch in spring 2017 from India) is a CubeSat mission which, besides other instrumentation, contains X-ray desk to perform efficiency tests of the X-ray optics. In this article the analysis of potential observational candidates for VZLUSAT-1 X-ray board is presented together with the suggestion of observational modes, laboratory measurements, and estimations of exposure settings.

Martin Blazek

Petr Pata

Adolf Inneman

Petr Skala

Astronomical Tasks for Tests of X-Ray Optics in VZLUSAT-1 Nanosatellite

The spatially conformally flat approximation (CFA) is a viable method to deduce initial conditions for the subsequent evolution of binary neutron stars employing the full Einstein equations. Here we analyze the viability of the CFA for the general relativistic hydrodynamic initial conditions of binary neutron stars. We illustrate the stability of the conformally flat condition on the hydrodynamics by numerically evolving &#x7e;100 quasicircular orbits. We illustrate the use of this approximation for orbiting neutron stars in the quasicircular orbit approximation to demonstrate the equation of state dependence of these initial conditions and how they might affect the emergent gravitational wave frequency as the stars approach the innermost stable circular orbit.

In-Saeng Suh

Grant J. Mathews

J. Reese Haywood

N. Q. Lan

Analysis of the Conformally Flat Approximation for Binary Neutron Star Initial Conditions

About this journal

<p><em>Advances in Astronomy</em> publishes in all areas of astronomy, astrophysics, and cosmology, and accepts observational and theoretical investigations into celestial objects and the wider universe.</p>


Journal profile

Meet the editorial board

<p>Chief Editor, Professor Trigo-Rodríguez (ICE, IEEC-CSIC), has a background in the formation of primitive solar system minor bodies, the study of their fragments in space and the analysis of their surviving rocks that arrived on the Earth.</p>


Editor spotlight

Submit your proposal

Do you think there is an emerging area of research that really needs to be highlighted? Or an existing research area that has been overlooked or would benefit from deeper investigation? Raise the profile of a research area by leading a Special Issue.

Special Issues

Author guidelines

Editorial board

Databases and indexing

Advances in Astronomy - Table of contents 2017

title

Advances in Astronomy publishes in all areas of astronomy, astrophysics, and cosmology, and accepts observational and theoretical investigations into celestial objects and the wider universe.

Advances in Astronomy