# Accepted Cycle 14 Observing Proposals

## STARS & WD

Proposal NumberSubject CategoryPI NameTitle
14200124STARS AND WDBergerThe Topology of Magnetic Fields and Coronae at the Bottom of the Main Sequence
14200172STARS AND WDTownsleyAn End in Fire: the Demise of a Massive Infrared Dark Cloud
14200176STARS AND WDHuenemoerderWolf-Rayet Winds at High Spectral Resolution
14200190STARS AND WDGetmanPortrait of a Giant HII Bubble: Star Formation Processes in the Cepheus Loop
14200198STARS AND WDHofnerX-Rays from the Massive Protostar IRAS 16562-3959
14200270STARS AND WDSkinnerColliding Winds in the Eclipsing Near-Contact Wolf-Rayet Binary CQ Cep
14200280STARS AND WDSkinnerHot on the Trail of the RW Aur Jet
14200349STARS AND WDOskinovaParticle Acceleration in the Bow Shock around zeta Oph
14200364STARS AND WDTanAn X-ray Census of the Young Stellar Population in Infrared Dark Clouds
14200392STARS AND WDWrightCan Massive Stars Form in Isolation?
14200448STARS AND WDGuarcelloStar formation close to the most massive stars in our Galaxy: unveiling the PMS members of Pismis 11
14200492STARS AND WDGuedelThe First FUor in Early X-Ray Outburst: HBC 722
14200532STARS AND WDLa PalombaraSearch for X-ray emission from a sample of luminous O-type subdwarfs
14200568STARS AND WDGuarcelloStar formation, disk evolution and coronal activity at low metallicity
14200592STARS AND WDPillitteriFAST AND FURIOUS: X-RAYS AND UV FROM THE WASP-18 SYSTEM.
14200631STARS AND WDCorcoranOccultation Measurements of the Embedded Wind Shock Distribution in the Nearest Eclipsing O-star Binary
14200632STARS AND WDLisseCharacterizing the X-ray & Stellar Wind Environment in the ~1 Gyr Late Heavy Bombardment System Eta Corvi
14200747STARS AND WDPetitNGC 1624-2: the O-type star with the strongest magnetic field
14200786STARS AND WDPooleyCatching an FUor in the Act: Chandra ToO Observations of Extreme Accretion onto Young Stars
14200801STARS AND WDKastnerCOMPACT AND DIFFUSE X-RAY SOURCES IN THE YOUNGEST PLANETARY NEBULAE
14200844STARS AND WDLeyderStudying the intriguing X-ray variability of HD 150136
14200906STARS AND WDPrincipeHeating the Primordial Soup: X-raying the Circumstellar Disk of T Cha
14200934STARS AND WDWrightProbing the Dynamo Mechanism in Fully Convective Stars
14200941STARS AND WDGuinanX-ray and UV Emissions of Cepheids: A Shockingly Different Picture of Cepheid Atmospheres Emerging

Subject Category: STARS AND WD

Proposal Number: 14200124

Title: The Topology of Magnetic Fields and Coronae at the Bottom of the Main Sequence

PI Name: Edo Berger

Until recently it was expected that magnetic dynamos would disappear beyond ~M3. Surprisingly, we have discovered a few ultracool dwarfs with strong and rotationally-periodic magnetic activity beyond ~M9. However, these objects do not have detectable X-ray emission due to a sharp drop-off in coronal activity in the lowest mass ultracool dwarfs. Recently, we discovered the fourth known periodic source, which has the strongest magnetic field measured to date (~10 kG). With a spectral type of M7 it is located in the "sweet-spot" for strong X-ray emission. Here we propose simultaneous X-ray/radio observations to trace the field and coronal topology and determine whether the corona of is coupled with the magnetic field structure through a search for in-phase periodic X-ray emission.

R.A. Dec. Target Name Det. Grating Exp.Time
13:14:20.40+13:20:01.202M1314+1320ACIS-SNONE36

Subject Category: STARS AND WD

Proposal Number: 14200172

Title: An End in Fire: the Demise of a Massive Infrared Dark Cloud

PI Name: Leisa Townsley

We will examine many facets of massive star formation and feedback with 60-ks ACIS-I observations of G333.3-0.4 and G333.1-0.4, nearby giant HII regions formed very recently in the giant molecular cloud (GMC) G333. We will study embedded massive stars, their surrounding compact clusters of pre-Main Sequence stars, and the wider context of star formation and GMC evolution in G333, which may be an evolved version of a massive infrared dark cloud. Based on our ACIS-I observation of G333.6-0.2, another of G333's massive star-forming sites, we expect to identify hundreds of cluster members and diffuse X-rays tracing wind-shocked plasma in each of these new pointings.

R.A. Dec. Target Name Det. Grating Exp.Time
16:20:39.50-50:39:58.60G333.1-0.4ACIS-INONE60
16:21:32.60-50:24:20.30G333.3-0.4ACIS-INONE60

Subject Category: STARS AND WD

Proposal Number: 14200176

Title: Wolf-Rayet Winds at High Spectral Resolution

PI Name: David Huenemoerder

The physical origin of X-ray emission in single Wolf-Rayet (WR) stars is not known. We request 450 ks on WR 6 with HETGS to establish which mechanisms operate in the winds of massive stars at the end of their evolution, shortly before a supernova or gamma-ray burst explosion. High-spectral resolution above 1 kev with HETGS is required to resolve emission lines from the hottest X-ray emitting plasma and thereby determine the location of wind structures. Principal diagnostics of X-ray emission line profiles in conjunction with our state-of-the-art stellar atmospheres code will help unravel current uncertainties in wind generation.

R.A. Dec. Target Name Det. Grating Exp.Time
06:54:13.00-23:55:42.00WR 6ACIS-SHETG450

Subject Category: STARS AND WD

Proposal Number: 14200190

Title: Portrait of a Giant HII Bubble: Star Formation Processes in the Cepheus Loop

PI Name: Konstantin Getman

We propose to study star formation associated with giant, asymmetric HII bubbles via three observations of the nearby bubble Cepheus Loop. An ACIS-I GO pointing (50ks) will characterize the rich and compact principal ionizing cluster Be59. XMM EPIC/pn pointings (2x30ks) will search for low-mass members of a suspected older generation of stars that could have both carved the Cepheus Loop and induced the formation of Be59, testing an important model for the morphology and evolution of asymmetric bubbles. Planned GTO pointings will quantify recent triggered star formation (TSF) in numerous cloudlets and pillars allowing a better understanding of the effect of TSF on the star formation rate in distant Galactic bubbles.

R.A. Dec. Target Name Det. Grating Exp.Time
00:02:17.00+67:25:09.10Be59ACIS-INONE50

Subject Category: STARS AND WD

Proposal Number: 14200198

Title: X-Rays from the Massive Protostar IRAS 16562-3959

PI Name: Peter Hofner

Understanding the formation of massive stars remains a challenge to present astrophysics. X-rays play an important role in the ionization of accretion disk and surrounding dense envelope, and their presence near the accreting massive star is expected due to hard shocks and magnetic processses. However, only a small number of massive protostars have been detected at very low S/N in the X-ray, all of them with luminosities of early B stars. We propose an 80 ks ACIS-I observation toward the newly discovered massive protostar IRAS 16592-3959, which is the most luminous massive protostar detected to date. The main goal of our observation is to obtain a higher S/N spectrum, which for the first time will allow reliable fitting of physical models, and to clarify the X-ray emission mechanism.

R.A. Dec. Target Name Det. Grating Exp.Time
16:59:41.60-40:03:43.60IRAS 16562-3959ACIS-INONE5

Subject Category: STARS AND WD

Proposal Number: 14200270

Title: Colliding Winds in the Eclipsing Near-Contact Wolf-Rayet Binary CQ Cep

PI Name: Stephen Skinner

One of the most remarkable Wolf-Rayet binaries known is the short-period eclipsing system CQ Cep (WN6 + O9; P = 1.64 d). The two stars are nearly in contact and wind-wind interaction capable of producing X-rays in a colliding wind (CW) shock is expected. Because of the close separation, CQ Cep provides a rare opportunity to observe a system where the winds collide at subterminal speeds and the CW shock is formed on or very close to the surface of the O star. CQ Cep was detected in an archived ASCA observation. We propose to observe CQ Cep with Chandra ACIS-S to place constraints on where the X-ray emission arises in the system and to test CW predictions at close separation.

R.A. Dec. Target Name Det. Grating Exp.Time
22:36:53.90+56:54:21.00HD 214419ACIS-SNONE85

Subject Category: STARS AND WD

Proposal Number: 14200280

Title: Hot on the Trail of the RW Aur Jet

PI Name: Stephen Skinner

Jets and outflows from accreting protostars and classical T Tauri stars (cTTS) influence star-formation by transporting mass, energy, and angular momentum. Optical studies reveal cool jet plasma (T ~ 1e4 K) but X-ray observations have recently detected much hotter plasma (T ~ 1e6 K) in the inner regions of cTTS jets, the origin of which is not yet understood. We propose to observe the nearby cTTS RW Aur with ACIS-S. Its spectacular bipolar jet is well-traced optically and viewed through very low extinction, making it an ideal X-ray target. Chandra's superb angular resolution will provide important information on properties of hot plasma in the inner jet that cannot be detected optically and is needed to model jet heating and cooling.

R.A. Dec. Target Name Det. Grating Exp.Time
05:07:49.60+30:24:05.20RW AurACIS-SNONE60

Subject Category: STARS AND WD

Proposal Number: 14200349

Title: Particle Acceleration in the Bow Shock around zeta Oph

PI Name: Lidia Oskinova

We propose to observe the bow shock produced by the runaway O-type star zeta Oph, the closest object of this kind. From its X-ray emission, we want to study the particle acceleration in an astrophysical shock, which is the key ingredient of cosmic-ray theory. It is not clear whether such kind of weak, but numerous shocks are the main sources of cosmic rays, or the supernova remnants. The proposed Chandra observation will clarify this important question by establishing whether high energy synchrotron radiation is emitted from bow shocks around massive stars. Our 75 ks exposure will result in a superb X-ray image of the resolved bow shock. The spectral information will provide a fundamental test of theoretical predictions on particle acceleration in the environs of massive stars.

R.A. Dec. Target Name Det. Grating Exp.Time
16:37:09.00-10:31:13.50Sh 2-27ACIS-INONE75

Subject Category: STARS AND WD

Proposal Number: 14200364

Title: An X-ray Census of the Young Stellar Population in Infrared Dark Clouds

PI Name: Jonathan Tan

Infrared dark clouds (IRDCs) represent an early phase of star cluster formation. Their study can thus provide key constraints on theoretical models of this process. While the gas properties of IRDCs are now well-studied, the young stellar object (YSO) content is very poorly explored. Only high spatial resolution Chandra X-ray observations can conduct a decisive census of this population. We propose to observe two nearby, massive IRDCs with ACIS-I. Combined with NIR and molecular line data, this will allow us to address fundamental questions, including: "What processes initiate star cluster formation?"; "Does star cluster formation take few or many local free-fall timescales?"; "Does the initial stellar mass function vary from the beginning to the end of star cluster formation?"

R.A. Dec. Target Name Det. Grating Exp.Time
18:53:18.50+01:24:48.00IRDC G34.4+0.23 (IRDC F)ACIS-INONE65

Subject Category: STARS AND WD

Proposal Number: 14200392

Title: Can Massive Stars Form in Isolation?

PI Name: Nicholas Wright

If massive stars can form in isolation is of great astrophysical importance with implications for how the initial mass function (IMF) is sampled and whether an upper limit exists for the most massive star in a cluster. Most isolated massive stars have been found to either be associated with previously unknown low-density stellar clusters or can be traced back to a cluster using proper motions. From the recent list of isolated massive stars from de Wit et al. (2005) only two candidates remain for isolated massive star formation. We are proposing 30 and 60ks ACIS-I observations of these two massive stars to search for undetected populations of young stars surrounding them, allowing us to identify the parental clusters. This will have major implications for theories of the origin of the IMF.

R.A. Dec. Target Name Det. Grating Exp.Time
14:15:01.60-61:42:24.40HD124314ACIS-INONE30
20:20:28.00+43:51:16.30HD193793ACIS-INONE60

Subject Category: STARS AND WD

Proposal Number: 14200448

Title: Star formation close to the most massive stars in our Galaxy: unveiling the PMS members of Pismis 11

PI Name: Mario Guarcello

The general impact of intense UV radiation fields on clusters evolution are not yet well understood. We propose a 100ks ACIS-I observation of the 3Myrs open cluster Pismis11, hosting the Blue Hyper-Giant HD80077, one of the most luminous star in our Galaxy. Its ionizing effects are more intense than those of early O stars, blue supergiants, and Luminous Blue Variables. HD80077 has completely dominated the radiation field in the cluster, which presents an unusually well-controlled laboratory to study the effects of UV irradiation on star and planet formation. This observation will detect cluster members down to 1Msolar. Combined with existing Spitzer and new optical photometry the study will provide an accurate assessment of cluster age, IMF and disk fraction.

R.A. Dec. Target Name Det. Grating Exp.Time
09:15:55.60-49:58:12.70Pismis11ACIS-INONE100

Subject Category: STARS AND WD

Proposal Number: 14200492

Title: The First FUor in Early X-Ray Outburst: HBC 722

PI Name: Manuel Guedel

FU Ori outbursts ("FUors") play an important role in the accretion history of a pre-main sequence star. They reveal themselves as brightness increases by several magnitudes in the optical/infrared. FUors are attributed to accretion disk instabilities heating the inner disk such that it entirely dominates the optical spectrum. They decline over many years to decades. Only a handful of FUors in optical eruption have been recorded during the past decades, and no FUor has been caught in X-ray outburst before the recent eruption of the bona-fide FUor HBC 722 in 2010. We have secured two X-ray snapshot observations and now propose to obtain a high resolution Chandra image and a CCD spectrum to continue study of this object in the framework of a multi-wavelength campaign.

R.A. Dec. Target Name Det. Grating Exp.Time
20:58:17.00+43:53:43.40HBC 722ACIS-SNONE30

Subject Category: STARS AND WD

Proposal Number: 14200532

Title: Search for X-ray emission from a sample of luminous O-type subdwarfs

PI Name: Nicola La Palombara

While many hot subdwarf stars have been deeply investigated in the optical and UV domain, only two sdO stars, HD49798 and BD+37 442, have been detected at X-rays. In both cases the observed emission shows a fast periodic modulation, indicating the presence of a WD or NS companion, likely powered by accretion. We propose the first systematic search for X-ray emission from a complete flux-limited sample of sdO stars, in order to constrain the presence of compact companions.

R.A. Dec. Target Name Det. Grating Exp.Time
09:24:26.40+36:42:53.30BD+37 1977HRC-INONE4
08:10:49.50+74:57:57.90BD+75 325HRC-INONE4
21:59:42.00+26:25:57.40BD+25 4655HRC-INONE4
17:46:31.90+39:19:09.10BD+39 3226HRC-INONE4
08:02:14.90-03:58:16.40BD-03 2179HRC-INONE4
21:51:11.00+28:51:50.40BD+28 4211HRC-INONE4
07:36:30.20-32:12:43.70CD-31 4800HRC-INONE4
09:30:46.80+48:16:23.80BD+48 1777HRC-INONE4
06:16:13.30+22:45:48.60LS V +22 38HRC-INONE4
10:39:36.70+43:06:09.30Feige 34HRC-INONE4
03:29:05.70+64:04:42.00LS I +63 198HRC-INONE4
09:20:10.10-45:31:54.90LSS 1275HRC-INONE4
13:53:08.20-46:43:42.30LSE 153HRC-INONE4
19:02:11.80-51:30:09.50LSE 263HRC-INONE4
12:41:51.80+17:31:19.80BD+18 2647HRC-INONE4
20:43:02.50+10:34:10.00LS IV +10 9HRC-INONE4
14:32:21.50-22:39:25.60BD-22 3804HRC-INONE4
16:23:44.00-12:12:33.60LS IV -12 1HRC-INONE4
19:55:38.20-23:13:42.20LSE 21HRC-INONE4

Subject Category: STARS AND WD

Proposal Number: 14200568

Title: Star formation, disk evolution and coronal activity at low metallicity

PI Name: Mario Guarcello

The metal content of gas is thought to have a strong impact on star formation. Unfortunately, the low metallicity young clusters that can probe star and planet formation in metal-poor environments are generally located at great distances: in the outer Galaxy or in the Magellanic Clouds. The one exception identified to date is the relatively nearby young cluster Dolidze25 (4kpc, age 4-6Myr). It is of especially low metallicity (Z=0.17Zsolar) and is the best target known for studying metal-poor star and planet formation. A 150ks ACIS-I observation, complemented by existing deep photometry from optical to 22micron, will for the first time probe the low metallicity IMF, protoplanetary disk evolution, and the coronal X-ray properties of disk-hosting and disk-less stars down to solar masses.

R.A. Dec. Target Name Det. Grating Exp.Time
06:45:05.10+00:16:15.60Dolidze 25ACIS-INONE150

Subject Category: STARS AND WD

Proposal Number: 14200592

Title: FAST AND FURIOUS: X-RAYS AND UV FROM THE WASP-18 SYSTEM.

PI Name: Ignazio Pillitteri

Recent observations demonstrate that magnetic and tidal interactions between hot-Jupiters and their host stars manifest as X-ray emission. These interactions, which are a strong function of separation, should accelerate the dynamical evolution of the planet while simultaneously disguising signs of age in the host star. We propose to study the X-ray and UV signatures of star planet interaction in WASP-18, an F6 star with an extreme hot Jupiter orbiting in less than one day at a distance of only 3.5 stellar radii. We ask a 90 ks ACIS-Chandra observation to observe the entire orbit for evidence of phase dependent interactions. Five HST orbits of COS FUV spectroscopy will reveal SPI effects in the chromosphere on transition region of the star.

R.A. Dec. Target Name Det. Grating Exp.Time
01:37:25.00-45:40:40.30WASP-18ACIS-INONE90

Subject Category: STARS AND WD

Proposal Number: 14200631

Title: Occultation Measurements of the Embedded Wind Shock Distribution in the Nearest Eclipsing O-star Binary

PI Name: Michael Corcoran

We propose four phase-constrained Chandra/HETGS observations of the massive, eclipsing, single-line spectroscopic binary $\delta$~Ori. Delta Ori is one of the fundamental calibrators of the mass-luminosity-radius relation in the upper HR diagram.These HETGS observations will, for the first time, provide an in-situ measurement of the distribution of the embedded, X-ray emitting shocks in the wind of an O star via radial velocity, occultation and $f/i$ ratio diagnostics, as well as determine the primary star's clumping-corrected mass loss rate. These observations will help resolve critical uncertainties in our understanding of the connection between stellar and mass loss parameters and pioneer new X-ray analysis methods in massive star astrophysics.

R.A. Dec. Target Name Det. Grating Exp.Time
05:32:00.40-00:17:56.70Delta OriACIS-SHETG125
05:32:00.40-00:17:56.70Delta OriACIS-SHETG125
05:32:00.40-00:17:56.70Delta OriACIS-SHETG125
05:32:00.40-00:17:56.70Delta OriACIS-SHETG125

Subject Category: STARS AND WD

Proposal Number: 14200632

Title: Characterizing the X-ray & Stellar Wind Environment in the ~1 Gyr Late Heavy Bombardment System Eta Corvi

PI Name: Carey Lisse

We propose a 40 ksec ACIS-S observation of the 1 Gyr old system Eta Corvi, the site of an on-going Late Heavy Bombardment (Lisse et al. 2012), in order to determine the spectrum of x-ray radiation in the burgeoning system, its origin in the stellar coronae and circumstellar debris belts, and its impact on the water and organics recently delivered to a rocky planet in the terrestrial habitability zone.

R.A. Dec. Target Name Det. Grating Exp.Time
12:32:04.20-16:11:45.60HD 109085ACIS-SNONE40

Subject Category: STARS AND WD

Proposal Number: 14200747

Title: NGC 1624-2: the O-type star with the strongest magnetic field

PI Name: Veronique Petit

This proposal is motivated by the very recent detection of an unprecedentedly strong magnetic field on the O star NGC 1624-2. With an inferred surface dipole field of 19 kG, its magnetic field is almost an order of magnitude stronger than any other O star's. With such strong confinement, one would expect a very large magnetosphere on NGC 1624-2. The majority of the stellar wind mass-flux should be trapped in closed field regions, with the strong wind flow leading to high-velocity shocks, very high temperatures, and hard X-ray emission. We propose to obtain phase-dependent ACIS-S data that will provide stringent tests of the Magnetically Confined Wind Shock (MCWS) paradigm of massive star X-ray emission in the most extreme magnetic O-type star known.

R.A. Dec. Target Name Det. Grating Exp.Time
04:40:37.30+50:27:41.00NGC 1624 2 (Max)ACIS-SNONE50
04:40:37.30+50:27:41.00NGC 1624 2 (Min)ACIS-SNONE50

Subject Category: STARS AND WD

Proposal Number: 14200786

Title: Catching an FUor in the Act: Chandra ToO Observations of Extreme Accretion onto Young Stars

PI Name: David Pooley

FU Orionis (FUor) outbursts are a transitory rapid accretion phase in the evolution of young stellar objects. We propose to obtain an X-ray spectrum during the rise to peak brightness of an FUor with Chandra. This phase has never been observed in X-rays and could reveal important information about the nature and source of the X-ray emission in these objects. In particular, it would provide a unique test of whether high-velocity jets are formed during the intense accretion event. These jets are expected to form X-ray dissociation regions, and X-ray emission does correlate with outflows from young stellar objects. If these jets only exist during the high levels of accretion during the rise to peak brightness, as they are thought to, X-ray observations during this time are crucial.

R.A. Dec. Target Name Det. Grating Exp.Time
FUor OutburstACIS-SNONE50

Subject Category: STARS AND WD

Proposal Number: 14200801

Title: COMPACT AND DIFFUSE X-RAY SOURCES IN THE YOUNGEST PLANETARY NEBULAE

PI Name: Joel Kastner

The community of planetary nebula (PN) astronomers is undertaking ChanPLaNS, the first systematic X-ray survey of PNe in the solar neighborhood. ChanPlaNS is yielding such fundamental, new results as the frequency of appearance and range of X-ray spectral characteristics of X-ray-emitting PN central stars and the evolutionary timescales of wind-shock-heated bubbles within PNe. Here, we propose the next phase of the survey, in which we will observe all (24) remaining known compact (radius <= 0.4 pc), young PNe within ~1.5 kpc that have yet to be observed by Chandra. This LP represents the next step toward understanding the relationship between PN X-ray emission and PN shaping processes, and its results will have broad and profound impact on the study of binary stars and wind interactions.

R.A. Dec. Target Name Det. Grating Exp.Time
09:52:44.50-46:16:51.00PN G273.6+06.1ACIS-SNONE20
21:59:35.20-39:23:08.00IC 5148ACIS-SNONE20
17:22:15.70-38:29:03.50NGC 6337ACIS-SNONE20
19:31:07.20-03:42:31.50PN G034.1-10.5ACIS-SNONE20
15:51:40.90-51:31:28.60PN G329.0+01.9ACIS-SNONE30
08:37:08.00-39:25:05.40ESO 313-5ACIS-SNONE30
19:01:59.30+02:09:18.00LBN 036.00-01.26ACIS-SNONE30
19:46:34.20-23:08:12.90ESO 526-3ACIS-SNONE30
17:45:57.70-30:12:00.60ESO 455-33ACIS-SNONE30
18:54:37.20-08:49:39.10IC 1295ACIS-SNONE30
20:16:24.00+30:33:53.20NGC 6894ACIS-SNONE30
16:01:21.10-34:32:35.80NGC 6026ACIS-SNONE30
09:27:03.00-56:06:21.10NGC 2899ACIS-SNONE30
16:12:58.10-36:13:46.10NGC 6072ACIS-SNONE30
21:26:23.50+62:53:31.80NGC 7076ACIS-SNONE30
05:56:23.90+46:06:17.50IC 2149ACIS-SNONE30
17:29:20.40-23:45:34.80NGC 6369ACIS-SNONE30
22:40:19.80+61:17:08.70NGC 7354ACIS-SNONE30
17:47:56.20-29:59:41.90ESO 455-42ACIS-SNONE30
04:06:59.40+60:55:14.40NGC 1501ACIS-SNONE20
16:31:30.60-40:15:12.30NGC 6153ACIS-SNONE30
17:05:10.50-40:53:08.40IC 4637ACIS-SNONE30
18:09:29.90-24:12:23.50ESO 521-39ACIS-SNONE30
11:50:17.70-57:10:56.90NGC 3918ACIS-SNONE30

Subject Category: STARS AND WD

Proposal Number: 14200844

Title: Studying the intriguing X-ray variability of HD 150136

PI Name: Jean-Christophe Leyder

HD 150136 is a multiple system harboring the nearest O3-type star. Its lightcurve indicates clear X-ray variability, whose origin is most likely due to a collision between the stellar winds. We propose to observe HD 150136 with Chandra over an entire orbital period in order to determine the cause of the X-ray variability. If the variability does follow the orbital period, HD 150136 must be a colliding-wind system, and we will be able to determine the mass-loss rates and terminal velocities of both components. In addition, we will use the eclipses to obtain a direct measurement of the radius of an O3 star for the very first time.

R.A. Dec. Target Name Det. Grating Exp.Time
16:41:20.40-48:45:46.70HD 150136ACIS-SHETG270

Subject Category: STARS AND WD

Proposal Number: 14200906

Title: Heating the Primordial Soup: X-raying the Circumstellar Disk of T Cha

PI Name: David Principe

T Cha is the only known example of a nearly edge-on actively accreting young star-disk system within 100 pc, and is likely orbited by a very low-mass companion or massive planet that has cleared an inner hole in its disk. We propose to obtain a 150 ks observation of T Cha with Chandra's HETGS with twin goals of (a) determining the intrinsic X-ray spectrum of T Cha so as to establish whether its X-ray emission can be attributed to accretion shocks or coronal emission, and (b) model the spectrum of X-rays absorbed by its gaseous disk. These results will serve as essential input to models of irradiated, planet-forming disks.

R.A. Dec. Target Name Det. Grating Exp.Time
11:57:13.50-79:21:31.50T ChaACIS-SHETG150

Subject Category: STARS AND WD

Proposal Number: 14200934

Title: Probing the Dynamo Mechanism in Fully Convective Stars

PI Name: Nicholas Wright

Solar-type stars emit X-rays from a corona that is powered by a magnetic dynamo driven by stellar rotation and internal convection. In fully convective stars the dynamo mechanism is not well understood, with observations suggesting similar X-ray properties to solar-type stars, but models of convective dynamos predicting different activity levels. Correlations between X-ray observations and rotation periods provide a glimpse into the dynamo processes at work in these stars. However only rapidly rotating fully convective stars have so far been studied in this way. We are proposing to observe three slowly-rotating fully convective M dwarfs to measure their X-ray luminosities and correlate these with their rotation periods, thus providing insights into the dynamo process at work in these stars

R.A. Dec. Target Name Det. Grating Exp.Time
03:13:23.00+04:46:29.40CD CetACIS-SNONE26
03:52:41.70+17:01:05.70GJ 3253ACIS-SNONE21
18:49:54.50+18:40:29.50G 184-31ACIS-SNONE8

Subject Category: STARS AND WD

Proposal Number: 14200941

Title: X-ray and UV Emissions of Cepheids: A Shockingly Different Picture of Cepheid Atmospheres Emerging

PI Name: Edward Guinan

We propose ACIS-S observations of the Cepheids delta Cep and beta Dor that we discovered to be X-ray and variable FUV sources. These complement existing/planned HST FUV spectroscopy and complete X-ray phase coverage. These stars show well-defined phased changes of FUV emission line fluxes from hot (10,000-300,000 K) plasmas that include O I, C II, Si IV and N V. The FUV emissions peak near pulsation phases between 0.75 to 1.05 P & likely originate from pulsation-induced shocks. We request 40 ksec exposures: 3 for d Cep & 1 for b Dor covering critical pulsation phases of ~0.7-1.0 P where the X-ray emissions should peak. These vital phases were not previously covered by XMM. The requested observations provide crucial tests of theories for atmospheric heating for Cepheids.

R.A. Dec. Target Name Det. Grating Exp.Time
05:33:37.50-62:29:23.30beta DorACIS-SNONE40