A bright reflection nebula shares the stage with a protostar and planet-forming disk in this Hubble image.
NASA, ESA, K. Stapelfeldt (Jet Propulsion Laboratory) and D. Watson (University of Rochester); Processing: Gladys Kober (NASA/Catholic University of America)
A disparate collection of young stellar objects bejewels a cosmic panorama in the star-forming region NGC 1333 in this new image from NASA’s Hubble Space Telescope. To the left, an actively forming star called a protostar casts its glow on the surrounding gas and dust, creating a reflection nebula. Two dark stripes on opposite sides of the bright point (upper left) are its protoplanetary disk, a region where planets could form, and the disk’s shadow, cast across the large envelope of material around the star. Material accumulates onto the protostar through this rotating disk of gas and dust, a product of the collapsing cloud of gas and dust that gave birth to the star. Where the shadow stops and the disk begins is presently unknown.
To the center right, an outflow cavity reveals a fan-shaped reflection nebula. The two stars at its base, HBC 340 (lower) and HBC 341 (upper), unleash stellar winds, or material flowing from the surface of the star, that clear out the cavity from the surrounding molecular cloud over time. A reflection nebula like this one is illuminated by light from nearby stars that is scattered by the surrounding gas and dust.
This reflection nebula fluctuates in brightness over time, which researchers attribute to variations in brightness of HBC 340 and HBC 341. HBC 340 is the primary source of the fluctuation as the brighter and more variable star.
HBC 340 and HBC 341 are Orion variable stars, a class of forming stars that change in brightness irregularly and unpredictably, possibly due to stellar flares and ejections of matter from their surfaces. Orion variable stars, so named because they are associated with diffuse nebulae like the Orion Nebula, eventually evolve into non-variable stars.
In this image, the four beaming stars near the bottom of the image and one in the top right corner are also Orion variable stars. The rest of the cloudscape is studded with other young stellar objects.
NGC 1333 lies about 950 light-years away in the Perseus molecular cloud, and was imaged by Hubble to learn more about young stellar objects, such as properties of circumstellar disks and outflows in the gas and dust created by these stars.
在这张哈勃图像中，一片明亮的反射星云与一颗原恒星及其行星形成盘同台呈现。
NASA, ESA, K. Stapelfeldt (Jet Propulsion Laboratory) and D. Watson (University of Rochester); Processing: Gladys Kober (NASA/Catholic University of America)
这幅由NASA哈勃太空望远镜拍摄的新图像展示了位于恒星形成区NGC1333的一片绚丽宇宙景观，多种年轻恒星天体点缀其间。画面左侧，一颗正在形成的恒星——原恒星——照亮周围的气体与尘埃，形成一片反射星云。亮点两侧各有一道暗带，上方左侧尤为清晰，这些暗条纹分别是原恒星的原行星盘以及该盘在包围恒星的大尺度物质包层上投下的阴影。原行星盘是可能孕育行星的区域，原恒星正通过这片旋转的气体和尘埃盘不断吸积物质，而这一结构源自最初坍缩并诞生恒星的气体与尘埃云。目前，阴影的终止位置与原行星盘的起始边界仍不清楚。
画面中部偏右，一处外流空腔显露出扇形的反射星云。在其底部的两颗恒星HBC340（下方）和HBC341（上方）释放出恒星风，即从恒星表面流出的物质，随着时间推移逐渐清理出周围分子云中的空腔。这类反射星云由附近恒星的光被周围气体与尘埃散射而照亮。
这片反射星云的亮度会随时间变化，研究人员认为这是由于HBC340和HBC341亮度本身发生变化所致，其中更明亮且变化更显著的HBC340是主要驱动因素。
HBC340和HBC341属于猎户座变星，这是一类亮度不规则、难以预测变化的形成中恒星，其变化可能与恒星耀斑以及物质从恒星表面喷射有关。猎户座变星因常与类似猎户座星云这样的弥散星云相关而得名，最终会演化为亮度稳定的恒星。
在这张图像中，画面底部附近的四颗耀眼恒星以及右上角的一颗恒星同样属于猎户座变星，其余云海中还分布着其他年轻恒星天体。
NGC1333位于英仙座分子云中，距离地球约950光年。哈勃对该区域进行观测，旨在深入了解年轻恒星天体的特性，例如环绕恒星的盘结构以及由这些恒星产生的气体和尘埃外流。
